RU2848278C1 - Methods and systems for tailings dewatering - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: group of inventions relates to a method for treating a stream, a method for treating a stream of wastes and a system for treating a stream. Methods may include providing a tailings stream, dewatering the tailings stream using a dewatering device to produce a first cake and a first residual effluent, bringing the first residual effluent into contact with one or more additives and dehydrating the first residual effluent with a solid-rotor centrifuge to produce a second cake and a second residual effluent. Methods may include providing a stream of tails, bringing the stream of tails into contact with one or more additives and dehydrating the stream of tails using a centrifuge with a solid rotor to obtain a first cake and a first residual output stream.

EFFECT: group of inventions provides improved methods of recycling tailings, including methods that can provide recycling of tailings in a dry state.

62 cl, 6 dwg, 6 tbl, 3 ex

Description

Cross-reference to related applications

This application claims priority to U.S. Provisional Patent Application No. 63/075,592, filed September 8, 2020, which is incorporated herein by reference.

State of the art

A number of industrial and mining processes generate tailings, the disposal of which can pose one or more challenges. Tailings may also contain valuable materials, which are also discarded.

Coal preparation plants, for example, can process thousands of tons of coal per hour, and a common method of disposing of fine tailings currently involves disposal in a wet tailings impoundment (WTF), such as a dam or reservoir. Fine tailings from coal preparation plants include materials that are discarded as slurry. Other plants, such as phosphate, iron oxide, and sulfide/carbonate ore beneficiations, can generate significant quantities of phosphate tailings, which can be disposed of in a similar manner.

Using wet tailings for fine waste disposal, including tailings, may be uneconomical for one or more reasons. For example, the tailings may contain economically valuable solids, which are not recovered. Another example is the key risk associated with wet tailings disposal over the life of a mine: the failure of the wet tailings. Furthermore, wet tailings areas are typically required to comply with government regulations, which may dictate the characteristics and/or accessibility of wet tailings areas.

There remains a need for improved tailings disposal methods, including those that can ensure dry tailings disposal. There also remains a need for improved methods for recovering solids from tailings, including those with economic value.

Disclosure of the essence of the invention

The present document provides methods and systems for dewatering tailings. The methods and systems can be applied to utilization (e.g., to produce a cake with one or more target characteristics, such as a target stackability), separation (e.g., to produce a residual effluent with one or more target characteristics, such as a target amount of suspended solids, etc.), recovery (e.g., to produce a cake containing one or more valuable materials, such as coal and/or other mineral(s)), or a combination thereof, and, in some embodiments, one or more of these applications can be achieved with relatively lower amounts of one or more additives (e.g., a flocculant) described herein.

The methods provided herein may have a relatively high solids recovery rate and/or produce products with a relatively low water content, even if the tailings are ultrafine in particle size and/or contain clays, such as non-swelling clays, swelling clays, or combinations thereof. In some embodiments, the methods provided herein reduce the water content of the tailings to an extent effective to produce a dewatered cake that provides improved (1) workability, (2) stacking properties, (3) geotechnical properties, or (4) a combination thereof, for dry disposal. The phrase "dry disposal," as used herein, may refer to the removal of extraneous water to facilitate efficient processing, transportation, stacking, and/or disposal at a specific location, or a combination thereof. The methods proposed in this document may provide for the pre-removal of coal or fine materials from the tailings, thereby potentially providing a valuable stream to reduce or lower dry disposal costs.

The present document provides methods for processing tailings streams. In some embodiments, the methods include providing a tailings stream; dewatering the tailings stream using a dewatering device to obtain a first cake and a first residual effluent stream; contacting the first residual effluent stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the first residual effluent stream using a solid rotor centrifuge to obtain a second cake and a second residual effluent stream.

In some embodiments, the methods include providing a tailings stream; dewatering the tailings stream using a dewatering device to produce a first cake and a first residual effluent stream; contacting the first residual effluent stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the first residual effluent stream using a solid rotor centrifuge to produce a second cake and a second residual effluent stream. The tailings stream may (1) have a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream, (2) contain clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream. The tailings stream may (1) have a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream, (2) contain swelling clay, wherein the swelling clay is in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, and/or (3) contain non-swelling clay, wherein the non-swelling clay is in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream. The first residual effluent stream may have a solids content of from about 0.2 wt. % to about 15 wt. % by weight of the first residual effluent stream. The first residual effluent stream may be introduced into a first residual effluent thickener to increase the solids content thereof prior to dewatering.

In some embodiments, the methods include providing a tailings stream; contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid bowl centrifuge to obtain a first cake and a first residual effluent. The tailings stream may have a solids content that (1) is in an amount of from about 10 wt. % to about 40 wt. % by weight of the tailings stream, (2) consists of a population of particles, wherein at least 25 wt. % of the population of particles is not retained by a 400 mesh woven metal screen, and/or (3) consists of a population of particles, wherein at least 10 vol. % of the population of particles has an average largest dimension of 2 microns or less.

The present document provides systems for processing streams. In some embodiments, the systems comprise a dewatering device configured to dewater a tailings stream to obtain a first cake and a first residual effluent stream, wherein the tailings stream (1) has a solids content of from about 2 wt. % to about 40 wt. % based on the weight of the tailings stream, and (2) contains clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content in the tailings stream, and wherein the first residual effluent stream has a solids content of from about 0.2 wt. % to about 15 wt. % based on the weight of the first residual effluent stream; and a solid rotor centrifuge configured to dewater the first residual effluent stream to obtain a second cake and a second residual effluent stream. In some embodiments, the systems comprise a dewatering device configured to dewater a tailings stream to produce a first cake and a first residual effluent stream, wherein the tailings stream (1) has a solids content of from about 2 wt. % to about 40 wt. % based on the weight of the tailings stream, and (2) comprises a swelling clay, wherein the swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, and/or (3) comprises a non-swelling clay, wherein the non-swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, and wherein the first residual effluent stream has a solids content of from about 0.2 wt. % to about 15 wt. % based on the weight of the first residual effluent stream; and a solid rotor centrifuge configured to dewater the first residual effluent stream to produce a second cake and a second residual effluent stream. In some embodiments, the systems include one or more additive feedstocks, wherein each of the one or more additive feedstocks is configured to contact the tailings stream with one or more additives; and a solid rotor centrifuge configured to dewater the tailings stream to produce a first cake and a first residual effluent stream.

Additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the aspects described herein, or may be obtained by dedicated research work. The advantages described herein may be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory only and not restrictive.

Brief description of the drawings

Fig. 1A is a schematic representation of an embodiment of the method and system presented in this document.

Fig. 1B is a schematic representation of an embodiment of the method and system presented in this document.

Fig. 2A is a schematic representation of an embodiment of the method and system presented in this document.

Fig. 2B is a schematic representation of an embodiment of the method and system presented in this document.

Fig. 3 schematically depicts an embodiment of the method and system presented in this document.

Fig. 4 shows the particle size distribution for an embodiment of the tailings flow.

Implementation of the invention

The present document provides methods and systems for dewatering streams, including tailings streams. Tailings streams dewatered using the methods and systems provided herein may contain clay, such as swelling clay. The methods and systems provided herein can be used to produce a cake containing one or more valuable materials (e.g., coal, mineral(s), etc.), a cake having one or more target characteristics (e.g., target stackability, etc.), a residual effluent having one or more target characteristics (e.g., target amount of suspended solids), or combinations thereof. For example, the methods and systems described herein can be used to produce an effluent having one or more target characteristics.

Tails

The methods and systems for dewatering streams provided herein can be used to dewater tailings from any source, such as coal tailings or mineral tailings resulting, for example, from the processing of phosphate, iron oxide, sulfide, carbonate ores, etc. The methods provided herein can be used to dewater tailings from multiple sources, such as (1) coal preparation plant tailings, (2) ore processing plant tailings, (3) XX settling basin tailings, (4) XX tailings, or (5) combinations thereof. The tailings source can include a waste stream from coal preparation plants, such as those that produce coking coal, thermal coal, etc. The tailings source can include silt and/or clay from the XX settling basin. The sludge is typically located in a settling basin fed from the XX area. The tailings source can include in-situ tailings in an existing XX. Typically, tailings from different sources may differ in one or more parameters, including, but not limited to, mineralogy, particle size distribution, carbon content, content of valuable element(s), presence of sulfates, chlorides or other dissolved salts, etc. The methods proposed herein may be adjusted based on one or more characteristics of the tailings to which the methods are applied.

Tailings streams dewatered by the processes described herein may have any solids content. For example, a tailings stream may have a solids content of from about 1 wt. % to about 50 wt. %, based on the weight of the tailings stream. In some embodiments, tailings streams dewatered by the processes provided herein have a solids content of from about 2 wt. % to about 40 wt. %, from about 5 wt. % to about 40 wt. %, from about 10 wt. % to about 40 wt. %, from about 10 wt. % to about 35 wt. %, from about 10 wt. % to about 30 wt. %, from about 10 wt. % to about 25 wt. %, from about 10 wt. % to about 20 wt. %, from about 10 wt. % to about 15 wt. %, from about 10 wt. % to about 35 wt. %, from about 15 wt. % to about 30 wt. % or from about 15 wt. % to about 25 wt. % of the tailings stream weight.

When the phrase "solids content" is used to describe a tailings stream, this phrase refers to suspended solids and does not include dissolved solids. The solids content of a tailings stream may include solids of any size, shape, or combination thereof. Solids, for example, may include an aggregate of particles, such as an aggregate of irregularly shaped particles. Solids may include an aggregate of particles of substantially the same size or several different sizes. An aggregate of particles may include any materials specified herein, such as mineral matter, carbonaceous matter, etc.

In some embodiments, the percentage, by weight, of solids content in the tailings stream that is not retained by the 60 mesh woven metal mesh is from about 50% to 100%, from about 60% to 100%, from about 65% to 100%, from about 70% to 100%, from about 75% to 100%, from about 80% to 100%, from about 85% to 100%, or from about 90% to 100%. In some embodiments, the percentage, by weight, of solids content in the tailings stream that are not retained by the 400 mesh woven metal mesh is from about 25% to about 80%, from about 25% to about 70%, from about 25% to about 70%, from about 50% to about 80%, from about 50% to about 70%, or from about 60% to about 70%. In some embodiments, the percentage, by weight, of solids content in the tailings stream that are not retained by the 400 mesh woven metal mesh is at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, or at least 80%. In some embodiments, the solids content consists of a population of particles wherein at least 10 vol.%, at least 20 vol.%, at least 30 vol.%, at least 40 vol.%, at least 50 vol.%, at least 60 vol.%, at least 70 vol.%, at least 80 vol.%, or at least 90 vol.% of the population of particles have an average largest dimension of 2 microns or less.

As used in this document, the phrase "X mesh" (e.g., 60 mesh) refers to a sieve identified by the number "X" (e.g., 60) in accordance with ANSI/ASTM E-11-81. Whenever the phrase "X mesh" is used in this document to describe a sieve, the sieve may, additionally or alternatively, be identified by its nominal opening size in microns in accordance with ISO 565 (Table 2): 1983. For example, a 60 mesh sieve has a nominal opening size of 250 µm, and a 400 mesh sieve has a nominal opening size of 38 µm.

The solids content of tailings streams dewatered by the methods described herein may include one or more types of solids. The one or more types of solids may include a high-carbon content substance, a mineral substance, or a combination of both. The one or more types of solids may include valuable mineral(s), another mineral substance, or a combination of both. However, the solids content does not include one or more additives described herein.

As used herein, the phrase "carbon-rich material" generally refers to coal, another carbon-containing material, or a combination thereof. The solids content of the tailings stream may include at least 20 wt. %, at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, or at least 90 wt. % of the carbon-rich material based on the weight solids content. In some embodiments, the solids content of the tailings stream includes from about 20 wt. % to about 90 wt. %, from about 20 wt. % to about 80 wt. %, from about 20 wt. % to about 70 wt. %, from about 20 wt. % to about 60 wt. %, from about 30 wt. % to about 90 wt. %, from about 30 wt. % to about 80 wt. %, from about 30 wt. % to about 70 wt. %, from about 30 wt. % to about 60 wt. %, from about 30 wt. % to about 50 wt. %, or from about 30 wt. % to about 40 wt. % of a high carbon content substance based on the mass solids content.

As used herein, the phrase _" mineral-containing material" generally refers to compounds containing valuable minerals, such as phosphorus(V) oxide (i.e., phosphorus pentoxide ( _P2O5 ) or _iron oxides (e.g., _Fe2O3 and _Fe3O4 )), sulfides or carbonates of metals such as Cu, Ni, Co, Zn, etc. The solids content of the tailings stream may include at least 20 wt. %, at least 30 wt. %, at least 40 wt. % _, at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, or at least 90 wt. % of the valuable mineral-containing material, based on the weight solids content. In some embodiments, the solids content of the tailings stream includes from about 20 wt. % to about 90 wt. %, from about 20 wt. % to about 80 wt. %, from about 20 wt. % to about 70 wt. %, from about 20 wt. % to about 60 wt. %, from about 30 wt. % to about 90 wt. %, from about 30 wt. % to about 80 wt. %, from about 30 wt. % to about 70 wt. %, from about 30 wt. % to about 60 wt. %, from about 30 wt. % to about 50 wt. %, or from about 30 wt. % to about 40 wt. % of the valuable mineral content based on the mass content of solids.

As used herein, the phrase "other mineral matter" generally refers to valueless solid inorganic matter, such as clays, that may be present in coal (and/or other carbonaceous material) deposits and/or coal (and/or other carbonaceous material) waste. Non-limiting examples of mineral matter include quartz, albite, anorthite, ankerite, dolomite, siderite, calcite, kaolinite, montmorillonite, smectite, illite, illite-smectite, muscovite, thobelite, anatase, chlorite, pyrite, and/or other sulfide minerals, or a combination thereof. As used herein, the term "clay" refers to a mineral matter that contains one or more clay minerals and, optionally, varying amounts of organic and/or detrital materials.

Some types of clay minerals can disintegrate in water into ultrafine particles (i.e., not retained by a 325 mesh screen). In some embodiments, the tailings stream contains at least one type of clay. Typically, the clay(s) present in the tailings streams have an average particle size of 2 microns or less. In some embodiments, the clay includes swelling clay, non-swelling clay, or a combination of both.

Clay may be present in any amount in the tailings streams dewatered by the methods described herein. In some embodiments, the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream. As used herein, the phrase "absolute content" refers to the absolute content of each mineral as determined by X-ray diffraction (XRD). In some embodiments, the clay is present in the tailings stream in an amount of at least 0.7%, at least 0.8%, at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 15%, at least 20%, or at least 25% by absolute content of the solids content of the tailings stream. In some embodiments, the clay is present in the tailings stream in an amount of from about 0.5% to about 50%, from about 0.7% to about 50%, from about 0.8% to about 50%, from about 1% to about 50%, from about 2% to about 50%, from about 3% to about 50%, from about 4% to about 50%, from about 5% to about 50%, from about 6% to about 50%, from about 7% to about 50%, from about 8% to about 50%, from about 9% to about 50%, from about 10% to about 50%, from about 15% to about 50%, from about 20% to about 50%, from about 25% to about 50%, from about 3% to about 40%, from about 4% to about 40%, from about 5% to about 40%, from about 6% to about 40%, from about 7% to about 40%, from about 8% to about 40%, from about 9% to about 40%, from about 10% to about 40%, from about 15% to about 40%, from about 20% to about 40%, from about 25% to about 40%, from about 3% to about 30%, from about 4% to about 30%, from about 5% to about 30%, from about 6% to about 30%, from about 7% to about 30%, from about 8% to about 30%, from about 9% to about 30%, from about 10% to about 30%, from about 15% to about 30%, from about 20% to about 30% or from about 25% to about 30% by absolute content of solids in the tailings stream.

As used herein, the phrase "swelling clay" refers to a clay mineral having a lattice that can expand primarily due to the penetration of water into one or more interstitial layers of the lattice. In some embodiments, a swelling clay can shrink/swell by at least 1% (as determined by a linear shrinkage test used for soils), depending on the clay's water content. In a shrink/swell test, the soil is a combination of various minerals, including clays. Some of these clays may be "swelling clays." Swelling clays in a soil will swell when wetted, causing the soil to expand. When expanded by a certain percentage, the classification system determines whether it is an "expansive soil" (see, e.g., Sridharan, A et al. "Classification procedures for expansive soils," Proc. Instn. Civ. Engrs. Geotech. Engng., 2000, 143, 235-240). The change in volume of swelling clay with water content may depend, at least in part, on the composition of the swelling clay, in particular the structure of the plates that form the lattice. Numerous published scientific papers have found that the presence of swelling clay significantly increases the difficulty of dewatering the tailings stream.

The swelling clay may be present in any amount in the tailings streams dewatered by the methods described herein. In some embodiments, the swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream. In some embodiments, the swelling clay is present in the tailings stream in an amount of at least 0.7%, at least 0.8%, at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 15%, at least 20%, or at least 25% by absolute content of the solids content of the tailings stream. In some embodiments, the swelling clay is in the tailings stream in an amount of from about 0.5% to about 50%, from about 0.7% to about 50%, from about 0.8% to about 50%, from about 1% to about 50%, from about 2% to about 50%, from about 3% to about 50%, from about 4% to about 50%, from about 5% to about 50%, from about 6% to about 50%, from about 7% to about 50%, from about 8% to about 50%, from about 9% to about 50%, from about 10% to about 50%, from about 15% to about 50%, from about 20% to about 50%, from about 25% to about 50%, from about 3% to about 40%, from about 4% to about 40%, from about 5% to about 40%, from about 6% to about 40%, from about 7% to about 40%, from about 8% to about 40%, from about 9% to about 40%, from about 10% to about 40%, from about 15% to about 40%, from about 20% to about 40%, from about 25% to about 40%, from about 3% to about 30%, from about 4% to about 30%, from about 5% to about 30%, from about 6% to about 30%, from about 7% to about 30%, from about 8% to about 30%, from about 9% to about 30%, from about 10% to about 30%, from about 15% to about 30%, from about 20% to about 30% or from about 25% up to about 30% by absolute content of the solids content of the tailings stream.

As used herein, the phrase "non-swelling clay" refers to a clay having a lattice that cannot adsorb water molecules and, therefore, is not subject to linear expansion due to the incorporation of water into one or more interstitial layers of the lattice. However, a non-swelling clay may still undergo volume expansion upon hydration due to the water being trapped between the clay particles. In some embodiments, a non-swelling clay has an expansion/contraction capacity of less than 0.5% (as determined by linear shrinkage) depending on the water content of the clay. In some embodiments, the non-swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream. In some embodiments, the non-swelling clay is present in the tailings stream in an amount of at least 0.7%, at least 0.8%, at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 15%, at least 20%, or at least 25% by absolute content of the solids content of the tailings stream. In some embodiments, the non-swelling clay is in the tailings stream in an amount of from about 0.5% to about 50%, from about 0.7% to about 50%, from about 0.8% to about 50%, from about 1% to about 50%, from about 2% to about 50%, from about 3% to about 50%, from about 4% to about 50%, from about 5% to about 50%, from about 6% to about 50%, from about 7% to about 50%, from about 8% to about 50%, from about 9% to about 50%, from about 10% to about 50%, from about 15% to about 50%, from about 20% to about 50%, from about 25% to about 50%, from about 3% to about 40%, from about 4% to about 40%, from about 5% to about 40%, from about 6% to about 40%, from about 7% to about 40%, from about 8% to about 40%, from about 9% to about 40%, from about 10% to about 40%, from about 15% to about 40%, from about 20% to about 40%, from about 25% to about 40%, from about 3% to about 30%, from about 4% to about 30%, from about 5% to about 30%, from about 6% to about 30%, from about 7% to about 30%, from about 8% to about 30%, from about 9% to about 30%, from about 10% to about 30%, from about 15% to about 30%, from about 20% to about 30% or from about 25% up to about 30% by absolute content of the solids content of the tailings stream.

When the tailings streams described herein contain one or more clays, the one or more clays may include at least one clay selected from one or more of the following clay categories: montmorillonite (i.e., smectite), illite, and kaolinite. In some embodiments, the tailings streams described herein contain a swelling clay, and the swelling clay contains illite-smectite, smectite, montmorillonite, or a combination thereof. In some embodiments, the tailings streams described herein contain a non-swelling clay, and the non-swelling clay contains kaolinite. In some embodiments, the tailings streams described herein contain smectite and kaolinite.

In some embodiments, tailings streams dewatered by the methods provided herein have a mineral residue of from about 1 wt. % to about 90 wt. %, from about 5 wt. % to about 90 wt. %, from about 1 wt. % to about 80 wt. %, from about 5 wt. % to about 80 wt. %, from about 10 wt. % to about 70 wt. %, from about 10 wt. % to about 60 wt. %, from about 10 wt. % to about 50 wt. %, from about 15 wt. % to about 50 wt. %, from about 15 wt. % to about 40 wt. %, from about 20 wt. % to about 40 wt. %, or from about 30 wt. % to about 40 wt. % of the mass content of solids in the tailings stream. In some embodiments, the tailings streams dewatered by the methods proposed herein have a mineral residue of less than 90 wt. %, less than 80 wt. %, less than 70 wt. %, less than 60 wt. %, less than 50 wt. %, less than 40 wt. %, less than 30 wt. %, less than 20 wt. %, less than 10 wt. % of the mass content of solids in the tailings stream.

Keki

The cake may be produced by one or more steps of the methods described herein. In some embodiments, the tailings stream is dewatered to produce a cake, such as a cake containing coal or valuable mineral(s). The cake produced by dewatering the tailings stream may be referred to herein as a "first cake."

The first cake may have any solids content of the tailings stream dewatered to form the first cake. In some embodiments, the first cake has at least 99% by weight of the solids content of the tailings stream dewatered to form the first cake. For example, if the tailings stream contains X grams of solids per kilogram of tailings stream, then dewatering one kilogram of tailings stream may result in the formation of a cake that contains at least (0.99*X) grams of solids.

In some embodiments, the first cake has from about 50 wt. % to about 99 wt. %, from about 50 wt. % to about 98 wt. %, from about 50 wt. % to about 97 wt. %, from about 50 wt. % to about 96 wt. %, from about 50 wt. % to about 95 wt. %, from about 50 wt. % to about 90 wt. %, from about 60 wt. % to about 99 wt. %, from about 60 wt. % to about 98 wt. %, from about 60 wt. % to about 97 wt. %, from about 60 wt. % to about 96 wt. %, from about 60 wt. % to about 95 wt. %, from about 60 wt. % to about 90 wt. %, from about 65 wt. % to about 99 wt. %, from about 65 wt. % to about 98 wt. %, from about 65 wt. % to about 97 wt. %, from about 65 wt. % to about 96 wt. %, from about 65 wt. % to about 95 wt. %, from about 65 wt. % to about 90 wt. %, from about 70 wt. % to about 99 wt. %, from about 70 wt. % to about 98 wt. %, from about 70 wt. % to about 97 wt. %, from about 70 wt. % to about 96 wt. %, from about 70 wt. % to about 95 wt. %, from about 70 wt. % to about 90 wt. %, from about 75 wt. % to about 85 wt. %, from about 80 wt. % to about 99 wt. %, from about 80 wt. % to about 98 wt. %, from about 80 wt. % to about 97 wt. %, from about 80 wt. % to about 96 wt. %, from about 80 wt. % to about 95 wt. %, from about 80 wt. % to about 90 wt. %, or from about 70 wt. % to about 99 wt. % of the dry solids content of the tailings stream.

The first cake may have a water content of from about 10 wt. % to about 40 wt. % based on the weight of the first cake. In some embodiments, the first cake has a water content of from about 15 wt. % to about 50 wt. %, from about 15 wt. % to about 45 wt. %, from about 15 wt. % to about 40 wt. %, from about 20 wt. % to about 45 wt. %, from about 20 wt. % to about 40 wt. %, from about 25 wt. % to about 40 wt. %, from about 25 wt. % to about 35 wt. %, from about 25 wt. % to about 30 wt. %, from about 30 wt. % to about 40 wt. %, or from about 30 wt. % to about 35 wt. % based on the weight of the first cake.

In some embodiments, the methods disclosed herein include dewatering a tailings stream to produce a first cake and a first residual effluent stream. The first residual effluent stream may be dewatered to produce a second residual effluent stream and a second cake. The second cake and the first cake may contain total solids, and the total solids may include any percentage of solids in the tailings stream.

In some embodiments, the total amount of solids present in the first cake and the second cake is at least 90 wt. % of the dry solids content of the tailings stream. In some embodiments, the total amount of solids present in the first cake and the second cake is at least 95 wt. % of the dry solids content of the tailings stream. In some embodiments, the total amount of solids present in the first cake and the second cake is at least 98 wt. % of the dry solids content of the tailings stream. In some embodiments, the total amount of solids present in the first cake and the second cake is at least 99 wt. % of the dry solids content of the tailings stream.

The second cake may have a water content of from about 10 wt.% to about 40 wt.%, based on the weight of the second cake. In some embodiments, the second cake has a water content of from about 15 wt.% to about 40 wt.%, from about 20 wt.% to about 40 wt.%, from about 25 wt.% to about 40 wt.%, from about 25 wt.% to about 35 wt.%, from about 25 wt.% to about 30 wt.%, or from about 30 wt.% to about 35 wt.%, based on the weight of the second cake.

Outgoing streams

In some embodiments, the methods disclosed herein include dewatering a tailings stream to produce a cake and an effluent stream. The cake and residual effluent stream obtained by dewatering the tailings stream may be referred to herein as a "first cake" and a "first residual effluent stream," respectively.

When dewatering a tailings stream with a certain solids content, the first portion of the solids content may be collected as a first cake, while the second portion of the solids content may be present in a first residual effluent stream. Thus, the first residual effluent stream may have a variable solids content, as it may depend on one or more factors, including, but not limited to, the percentage of solids in the tailings stream that are collected in the first cake.

In some embodiments, the first residual effluent stream, before (1) optionally entering the first residual effluent thickener and (2) contacting with one or more additives, has a solids content of from about 0.2% to about 15% by weight, from about 0.2% to about 14% by weight, from about 0.2% to about 13% by weight, from about 0.2% to about 12% by weight, from about 0.2% to about 11% by weight, from about 0.2% to about 10% by weight, from about 0.2% to about 9% by weight, from about 0.2% to about 8% by weight, from about 0.2% to about 7% by weight, from about 0.2% to about 6% by weight, from about 0.2% to about 5% by weight. %, from about 0.2 wt. % to about 4 wt. %, from about 0.2 wt. % to about 3 wt. %, from about 0.2 wt. % to about 2 wt. %, or from about 0.2 wt. % to about 1 wt. %, based on the weight of the first residual effluent stream.

In some embodiments, the methods provided herein include introducing a first residual effluent stream into a first residual effluent thickener prior to dewatering the first residual effluent stream. The first residual effluent thickener may increase the solids content of the first residual effluent stream by from about 1 to about 40 weight percentage points, from about 1 to about 25 weight percentage points, from about 1 to about 20 weight percentage points, from about 1 to about 15 weight percentage points, or from about 1 to about 10 weight percentage points. Thus, in some embodiments, the first residual effluent stream, after being "thickened" by the first residual effluent thickener, has a solids content of from about 1.2 wt. % to about 55 wt. %, from about 1.2 wt. % to about 54 wt. %, from about 1.2 wt. % to about 53 wt. %, from about 1.2 wt. % to about 52 wt. %, from about 1.2 wt. % to about 51 wt. %, from about 1.2 wt. % to about 50 wt. %, from about 1.2 wt. % to about 49 wt. %, from about 1.2 wt. % to about 48 wt. %, from about 1.2 wt. % to about 47 wt. %, from about 1.2 wt. % to about 46 wt. %, from about 1.2 wt. % to about 45 wt. %, from about 1.2 wt. % to about 44 wt. %, from about 1.2 wt. % to about 43 wt. %, from about 1.2 wt. % to about 42 wt. %, from about 1.2 wt. % to about 41 wt. %, from about 1.2 wt. % to about 30 wt. %, from about 1.2 wt. % to about 29 wt. %, from about 1.2 wt. % to about 28 wt. %, from about 1.2 wt. % to about 27 wt. %, from about 1.2 wt. % to about 26 wt. %, from about 10 wt. % to about 35 wt. %, from about 10 wt. % to about 34 wt. %, from about 10 wt. % to about 33 wt. %, from about 10 wt. % to about 32 wt. %, from about 10 wt. % to about 31 wt. %, from about 10 wt. % to about 30 wt. %, from about 10 wt. % to about 29 wt. %, from about 10 wt. % to about 28 wt. %, from about 10 wt. % to about 27 wt. %, from about 10 wt. % to about 26 wt. %, from about 20 wt. % to about 35 wt. %, about 20 wt. % to about 34 wt. %, from about 20 wt. % to about 33 wt. %, from about 20 wt. % to about 32 wt. %, from about 20 wt. % to about 31 wt. %, from about 20 wt. % to about 30 wt. %, from about 20 wt. % to about 29 wt. %, from about 20 wt. % to about 28 wt. %, from about 20 wt. % to about 27 wt. %, from about 20 wt. % to about 26 wt. %, from about 25 wt. % to about 35 wt. %, from about 25 wt. % to about 34 wt. %, from about 25 wt. % to about 33 wt. %, from about 25 wt. % to about 32 wt. %, from about 25 wt. % to about 31 wt. %, from about 25 wt. % to about 30 wt. %, from about 25 wt. % to about 29 wt. %, from about 25 wt. % to about 28 wt. %, from about 25 wt. % to about 27 wt. %, or from about 25 wt. % to about 26 wt. %, based on the weight of the first residual effluent stream.

In some embodiments, the methods provided herein include dewatering a dewatered stream, such as a first residual effluent stream, to produce a cake and another dewatered stream, which may be referred to herein as a "second cake" and a "second residual effluent stream," respectively. Thus, the second residual effluent stream may have a solids content that varies because it may depend on (1) the percentage of solids in the tailings stream that are collected in the first cake, and (2) the percentage of solids in the first residual effluent stream that are collected in the second cake.

In some embodiments, the amount of suspended solids in the second residue effluent stream is from about 10 mg/L to about 750 mg/L, from about 10 mg/L to about 700 mg/L, from about 10 mg/L to about 650 mg/L, from about 10 mg/L to about 600 mg/L, from about 10 mg/L to about 550 mg/L, from about 10 mg/L to about 500 mg/L, from about 10 mg/L to about 450 mg/L, from about 10 mg/L to about 400 mg/L, from about 10 mg/L to about 350 mg/L, from about 10 mg/L to about 300 mg/L, from about 10 mg/L to about 250 mg/L, from about 10 mg/L to about 200 mg/L, from about 10 mg/L to about 150 mg/L, or from about 10 mg/L to about 100 mg/L. In some embodiments, the second residual effluent stream has a turbidity of from about 10 NEF to about 100 NEF, from about 10 NEF to about 75 NEF, from about 10 NEF to about 50 NEF, or from about 10 NEF to about 25 NEF. In some embodiments, the second residual effluent stream comprises water in an amount of at least 95 wt. %, 98 wt. %, or 99 wt. % of the second residual effluent stream.

Supplements

The methods provided herein may include the use of one or more additives. In some embodiments, the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent. Thus, the one or more additives may include a flocculant, a coagulant, a conditioning additive, a surfactant, a seeding agent, or a combination thereof.

In some embodiments, one or more additives comprise a flocculant. In some embodiments, the flocculant is a nonionic flocculant. In some embodiments, the flocculant is an anionic flocculant. In some embodiments, the flocculant is a cationic flocculant. In some embodiments, the flocculant is a fatty acid/lipid flocculant. In some embodiments, the flocculant is a polymeric flocculant that includes a polymer such as an acrylic polymer (e.g., polyacrylamide), a polysaccharide (e.g., chitosan), poly(diallyldimethylammonium chloride), etc. When the flocculant is a polymeric flocculant, the polymer can be a high molecular weight polymer (i.e., a polymer having an _Mw of at least 100,000 g/mol) or a very high molecular weight polymer (i.e., a polymer having an _Mw of at least 10,000,000 g/mol). In some embodiments, the flocculant is a non-ionic polymeric flocculant. In some embodiments, the flocculant is a high or very high molecular weight non-ionic polymeric flocculant. In some embodiments, the flocculant is an anionic polymeric flocculant. In some embodiments, the flocculant is an anionic polymeric flocculant with a high or very high molecular weight. In some embodiments, the flocculant is a cationic polymeric flocculant. In some embodiments, the flocculant is a high or very high molecular weight cationic polymeric flocculant. In some embodiments, the flocculant is a commercially available flocculant such as NALCO™ 749222 flocculant, YONGXING™ YX1224-6 flocculant, YONGXING™ PAM flocculant, YIXING™ ARAM01 flocculant, ULTRACLEAR™ PROFLOCCULANT™ flocculant, GLORY™ flocculant, ZETAG™ 8127 flocculant (BASF, USA), ZETAG™ 4145 flocculant (BASF, USA), MAGNAFLOC® LT20 flocculant (BASF, USA), MAGNAFLOC® 338 flocculant (BASF, USA), MAGNAFLOC® 10 flocculant (BASF, USA), flocculant MAGNAFLOC® 155 (BASF, USA), flocculant RHEOMAX® 1050 (BASF, USA), flocculant RHEOMAX® ETD 9010 (BASF, USA), polyacrylamide flocculant MAGNAFLOC® LT27AG (BASF, USA), acrylic homopolymer flocculant ZETAG™ 7109 (BASF, USA), flocculant MAGNAFLOC® 333 (BASF, USA), flocculant FLOBEADS® KB206SH (SNF, UK), flocculant FLOBEADS® KB156 (SNF, UK), flocculant FLOPAM® FO4190 (SNF, UK), flocculant FLOPAM® FO4140 (SNF, UK), flocculant FLOQUAT® TS 45 SH (SNF, UK), flocculant FLOPAM® FA920VHM (SNF, UK), flocculant FLOPAM® FA920VHR (SNF, UK), flocculant FLOPAM® FA920SD (SNF, UK), flocculant FLOPAM® FA920SHD (SNF, UK), flocculant FLOPAM® FA920 (SNF, UK), flocculant ALCLAR® 5000 (BASF, USA), flocculant ALCLAR® 600 (BASF, USA), flocculant ALCLAR® 661 (BASF, USA), flocculant ALCLAR® HP20 (BASF, USA), flocculant ALCLAR® HP21 (BASF, USA), flocculant ALCLAR® HP22 (BASF, USA), flocculant DRIMAX® 1235 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1238 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1240 (Allied Colloids Ltd., UK), flocculant LUPROMIN® F-20X (BASF, USA), flocculant LUPROMIN® FP 18 AS (BASF, USA), flocculant LUPROMIN® FP 199 (BASF, USA), HI-TEX® 82230 (Hi-Tex Corp, USA), or a combination thereof.

The flocculant may be in any form prior to its use in the methods provided herein. For example, the flocculant may be in powder form prior to its use in the methods provided herein. The powder may comprise a collection of particles of any shape or size. In some embodiments, less than 2% of the powder particles are retained by a 20 mesh woven metal mesh, a 25 mesh woven metal mesh, a 30 mesh woven metal mesh, or a 35 mesh woven metal mesh.

A flocculant, such as a powder flocculant, can be combined with a liquid, typically pure water, prior to use in the methods disclosed herein. The flocculant can be fully or partially soluble in the liquid. In some embodiments, the flocculant is in powder form, and the powder is mixed with pure water to form the combination. The pH of the water can be adjusted, if necessary or desired, prior to adding the flocculant to the water. Selecting a pH that increases the ionic nature of the flocculant may allow for the use of a lower flocculant dosage. Commercially available flocculants may include liquids into which the flocculant has been added; therefore, in some embodiments, the methods disclosed herein comprise providing a liquid into which the flocculant powder has been added.

In some embodiments, one or more additives comprise a coagulant. In some embodiments, the coagulant is a cationic coagulant. In some embodiments, the coagulant is a polymeric coagulant that comprises a polymer, such as polyacrylamide. When the coagulant is a polymeric coagulant, the polymer can be a high molecular weight polymer (i.e., a polymer having an _Mw of at least 100,000 g/mol) or a very high molecular weight polymer (i.e., a polymer having an _Mw of at least 10,000,000 g/mol). In some embodiments, the coagulant is a cationic polymeric coagulant. In some embodiments, the coagulant is a high or very high molecular weight cationic polymeric coagulant. In some embodiments, the coagulant is a commercially available inorganic coagulant, which may be an inorganic salt such as magnesium chloride, iron chloride or sulfate, aluminum chloride or sulfate, etc., and/or an organic polymer such as MAGNAFLOC® LT7991 coagulant (BASF, USA), MAGNAFLOC® LT32 coagulant (BASF, USA), MAGNAFLOC® LT38 coagulant (BASF, USA), MAGNAFLOC® 1425 coagulant (BASF, USA), FLOQUAT® FL2549SEP coagulant (SNF, UK), FLOQUAT® FLB1725SEP (SNF, UK), FLOQUAT® FL5323 (SNK, UK), or a combination thereof.

The conditioning additive and/or surfactant may include technical inorganic products, such as those commonly used in coal and mineral processing operations, as well as other common water treatment applications. The type and/or amount of conditioning additive, surfactant, or both conditioning additive and surfactant may depend on a number of factors, such as one or more properties of the tailings stream, one or more properties of another additive used, such as a flocculant or coagulant, etc.

In some embodiments, one or more additives include a conditioning additive. The conditioning additive may include an inorganic salt. Non-limiting examples of inorganic salts that can be used include metal halides, metal sulfates, metal hydroxides, or combinations thereof. Metal halides may include a metal chloride, such as magnesium chloride, iron chloride, sodium chloride, etc. Metal sulfates may include magnesium sulfate, aluminum sulfate, potassium sulfate, etc. Metal hydroxides may include calcium hydroxide (e.g., slaked lime).

In some embodiments, one or more additives include a surfactant. The surfactant may include an inorganic surfactant.

In some embodiments, one or more additives include a flocculant and, optionally, a seeding agent. In some embodiments, one or more additives include a flocculant and a coagulant and, optionally, a seeding agent. In some embodiments, one or more additives include a flocculant, a coagulant, and a conditioning additive (e.g., an inorganic conditioning additive), and, optionally, a seeding agent. In some embodiments, one or more additives include a flocculant, a coagulant, a conditioning additive (e.g., an inorganic conditioning additive), and a surfactant, and, optionally, a seeding agent. The flocculant and coagulant in some embodiments include (1) a nonionic, anionic, or cationic flocculant and (2) a cationic coagulant.

One or more additives may generally be used in any amount in the methods provided herein. In some embodiments, the one or more additives comprise a flocculant, and the first residual effluent stream is contacted with the flocculant in an amount of from about 1 gram to about 500 grams, from about 100 grams to about 500 grams, from about 200 grams to about 500 grams, from about 250 grams to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, from about 1 gram to about 50 grams, from about 1 gram to about 40 grams, from about 1 gram to about 30 Grams, from about 1 gram to about 20 grams, or from about 1 gram to about 10 grams of flocculant per ton of dry solids content of the tailings stream. These amounts represent amounts of flocculant only and do not include flocculant-free liquid, such as water, with which the flocculant may be combined. Thus, for example, if 10 grams of flocculant are to be added per ton of dry solids content in the tailings stream, then 10 grams of flocculant powder may be added per ton of dry solids content in the tailings stream, or a volume of a water/flocculant combination that contains 10 grams of flocculant powder may be added per ton of dry solids content in the tailings stream. This example of a volume of water/flocculant combination may be described herein as containing 10 grams of "active flocculant." Other additives described herein may be added in these amounts.

In some embodiments, one or more additives comprise a coagulant, and the first residual effluent stream is contacted with the coagulant in an amount of from about 1 gram to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, or from about 1 gram to about 50 grams of coagulant per ton of dry solids content in the tailings stream.

In some embodiments, one or more additives include a conditioning additive, a surfactant, or a combination thereof, and the first residual effluent stream is contacted with the conditioning additive or surfactant in an amount of from about 1 gram to about 5,000 grams, from about 1 gram to about 4,000 grams, from about 1,000 grams to about 4,000 grams, from about 1,000 grams to about 3,000 grams, or about 2,000 grams of conditioning additive or surfactant per ton of dry matter content in the tailings stream. The amount of conditioning additive and/or surfactant can be selected to achieve a target cation concentration.

In some embodiments, one or more additives include a seeding agent. The seeding agent may include a collection of particles that are larger in size than the solids contained in the tailings stream. For example, the seeding agent may include a collection of particles that have an average largest particle size that is larger than (1) the average largest particle size of the solids contained in the tailings stream, (2) the largest particle size of the solids contained in the tailings stream, or (3) a combination thereof. In some embodiments, the seeding agent is obtained from a suspended bed separator (SBS) and may include fine waste from the SBS. In some embodiments, the seeding agent is obtained from a spiral waste stream, a reverse classifier waste stream, or another medium size separator, or a combination thereof.

The first residual effluent stream may be contacted with any amount of seeding agent. The amount of seeding agent used in the methods disclosed herein may depend on one or more factors, such as the target moisture content of the cake, such as the second cake, obtained by the methods disclosed herein.

The first residual effluent stream may have a solids content, and in some embodiments, the weight ratio of the solids content to the amount of seeding agent contacted with the first residual effluent stream is from about 0.7:1 to about 1:0.7, from about 0.8:1 to about 1:0.8, from about 0.9:1 to about 1:0.9, from about 0.95:1 to about 1:0.95, from about 0.99:1 to about 1:0.99, or about 1:1. Without wishing to be bound by any particular theory, it is believed that embodiments of the methods proposed herein can recover at least 98% or at least 99% of the solids contained in the tailings stream, with or without contacting the first residual effluent stream with a seeding agent, but the use of a seeding agent can reduce the water content of the cake, such as the second cake.

In some embodiments, the one or more additives comprise a flocculant and a seeding agent, and the first residual effluent is contacted with the flocculant in an amount of from about 1 gram to about 500 grams, from about 100 grams to about 500 grams, about 200 grams to about 500 grams, from about 250 grams to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, from about 1 gram to about 50 grams, from about 1 gram to about 40 grams, from about 1 gram to about 30 grams, from about 1 gram to about 20 grams, or from about 1 gram to about 10 grams, or about 50 grams of flocculant per ton of solids content in the tailings stream; and the weight ratio of solids content to the amount of seeding agent contacted with the first residual effluent stream is from about 0.7:1 to about 1:0.7, from about 0.8:1 to about 1:0.8, from about 0.9:1 to about 1:0.9, from about 0.95:1 to about 1:0.95, from about 0.99:1 to about 1:0.99, or about 1:1. The flocculant and seeding agent may be added independently at any point in the process described herein.

In some embodiments, the one or more additives comprise a flocculant and a conditioning additive, and the first residual effluent stream is contacted with the flocculant in an amount of from about 1 gram to about 500 grams, from about 100 grams to about 500 grams, from about 200 grams to about 500 grams, from about 250 grams to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, from about 1 gram to about 50 grams, from about 1 gram to about 40 grams, from about 1 gram to about 30 grams, from about 1 gram to about 20 grams, or from about 1 gram to about 10 grams, or about 50 grams of flocculant per ton of dry matter content in the tailings stream; and the first residual effluent stream is contacted with a conditioning additive in an amount of from about 1 gram to about 5000 grams, from about 1 gram to about 4000 grams, from about 1000 grams to about 4000 grams, from about 1000 grams to about 3000 grams, or about 2000 grams of conditioning additive per ton of dry matter contained in the tailings stream. The flocculant and the conditioning additive may be added independently at any point in the process described herein.

Methods and systems

The present document provides methods and systems for treating a stream, including dewatering a stream, that contains swelling clay.

Double dewatering methods and systems

In some embodiments, the methods include providing a tailings stream; dewatering the tailings stream using a dewatering device to obtain a first cake and a first residual effluent stream; contacting the first residual effluent stream with one or more additives; and dewatering the first residual effluent stream using a solid rotor centrifuge to obtain a second cake and a second residual effluent stream.

The tailings stream may originate from any one or more of the sources described herein and/or have any one or more of the features described herein. For example, the tailings stream may (1) have a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream, (2) contain clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream. The clay may include swelling clay, non-swelling clay, or a combination thereof. As a further example, the tailings stream may (1) have a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream, (2) contain swelling clay, wherein the swelling clay is in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, (3) contain non-swelling clay, wherein the non-swelling clay is in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, or (4) be a combination thereof.

In some embodiments, providing a tailings stream includes (1) introducing the waste stream into a waste stream thickener, and (2) collecting the tailings stream (i.e., the undersize product) from the waste stream thickener. After collecting the tailings stream from the waste stream thickener, the tailings stream can be diluted. For example, the tailings stream can be diluted with an amount of liquid sufficient to impart to the tailings stream a target mass percentage of solids, such as from about 10 wt.% to about 40 wt.% of the mass of the tailings stream.

The methods proposed herein may include dewatering a tailings stream using a dewatering device to produce a first cake and a first residual effluent. Any known dewatering device may be used to dewater the tailings stream. For example, the dewatering device may include a belt press filter, a horizontal belt vacuum filter, a rotary drum vacuum filter, a rotary vacuum disc filter, a screen centrifuge, a steep cone paste thickener, a membrane filter press, a solid rotor centrifuge (used to dewater the first residual effluent), or an additional solid rotor centrifuge.

In some embodiments, the tailings stream is dewatered using a dewatering device that includes a solid-rotor centrifuge that produces a first cake and a first residual effluent, wherein the first residual effluent comprises a first centrate from the solid-rotor centrifuge. For example, the dewatering device of Fig. 1A may be a solid-rotor centrifuge, and therefore the first residual effluent 103 may be a centrate from the solid-rotor centrifuge. When the dewatering device 120 of Fig. 1A is a solid-rotor centrifuge, the method/system of Fig. 1A includes a solid rotor centrifuge 130 and, as referred to herein, an "additional solid rotor centrifuge" 120. In some embodiments, the dewatering device is a solid rotor centrifuge, as shown, for example, in Fig. 1B and Fig. 2B. When the dewatering device is a solid rotor centrifuge, the same solid rotor centrifuge is used to dewater a feed stream, such as a tailings stream, and a first residual effluent stream, as shown, for example, in Fig. 1B and Fig. 2B.

The methods proposed herein may include dewatering the first residual effluent stream using a solid-rotor centrifuge. When the tailings stream is dewatered using a solid-rotor centrifuge, the solid-rotor centrifuges used to dewater the tailings stream and the first residual effluent stream may be the same or different and/or may operate at the same or different parameters.

Without wishing to be bound by any particular theory, it is believed that the first residual effluent stream, at least in some embodiments, will have a relatively higher percentage of swelling clays than the tailings stream.

Before dewatering using a solid-rotor centrifuge, the first residual effluent stream may be subjected to a process and/or treatment that increases the solids content of the first residual effluent stream. In some embodiments, the methods include introducing the first residual effluent stream into a first residual effluent thickener before dewatering the first residual effluent stream using a solid-rotor centrifuge. The first residual effluent thickener can increase the solids content of the first residual effluent stream by from about 1 to about 40 weight percentage points, as described herein. For example, if the first residual effluent stream has a solids content of about 5 wt. % based on the weight of the first residual effluent stream, then introducing the first residual effluent stream into the first residual effluent thickener can increase the solids content to from about 6 wt. % to about 45 wt. % based on the weight of the first residual effluent stream collected from the first residual effluent thickener. In some embodiments, the thickener of the first residual effluent stream at least doubles the weight percentage of solids present in the first residual effluent stream. For example, if the first residual effluent stream has a solids content of about 5 wt.% of the weight of the first residual effluent stream, then introducing the first residual effluent stream into the thickener of the first residual effluent stream can increase the solids content to at least 10 wt.% of the weight of the first residual effluent stream.

Any thickener may be used in the methods provided herein as a thickener of the first residual effluent stream, and the underflow of the thickener of the first residual effluent stream may be collected as a "thickened" first residual effluent stream.

An embodiment of the method/system is shown in Fig. 1A. The system/method 100 of Fig. 1A includes providing a tailings stream 101 and dewatering the tailings stream 101 using a dewatering device 110 to obtain a first residual effluent stream 103 and a first cake 102. The first cake 102 can be collected using any known equipment, such as a conveyor. The first residual effluent stream 103 is then introduced into a first residual effluent thickener 120. In the embodiment shown in Fig. 1A, the first residual effluent stream 103 is contacted with one or more additives from at least one feedstock (126a, 126b, 126c) in communication with an additive source 125, (1) before 126a the first residual effluent stream 103 is introduced into the first residual effluent thickener 120, (2) simultaneously as 126b the first residual effluent stream 103 is introduced into the first residual effluent thickener 120, (3) after 126c the first residual effluent stream 103 has been collected as an underflow from the first residual effluent thickener 120, or (4) any combination thereof. After adding one or more additives (126a, 126b, 126c), the first residual effluent stream 104 containing the additives is dewatered using a solid rotor centrifuge 130 to obtain a second cake 106 and a second residual effluent stream 107. The second cake 106 can be collected by any known equipment, such as a conveyor, which can be the same conveyor that is used to collect the first cake 102. The additive source 125 in some embodiments is a tank containing two or more additives. The additive source 125 in some embodiments includes at least two tanks, each of which contains a different additive, and the different additives can be added independently (1) before 126a the first residual effluent stream 103 is introduced into the first residual effluent thickener 120, (2) simultaneously as 126b the first residual effluent stream 103 is introduced into the first residual effluent thickener 120, (3) after 126c the first residual effluent stream 103 has been collected as an undersize product from the first residual effluent thickener 120, or (4) any combination thereof.

An embodiment of the method/system is shown in Fig. 1B. The system/method 130 of Fig. 1B includes providing a tailings stream 131 and dewatering the tailings stream 131 using a solid rotor centrifuge 140 to produce a first residual effluent stream 133 and a first cake 132.

The first cake 132 can be collected using any known equipment, such as a conveyor. The first residual effluent stream 133 is then introduced into the first residual effluent stream thickener 150. In the embodiment shown in Fig. 1B, the first residual effluent stream 133 is contacted with one or more additives from at least one additive feedstock (146a, 146b, 146c) in communication with an additive source 145, (1) before 146a the first residual effluent stream 133 is introduced into the first residual effluent thickener 150, (2) simultaneously as 146b the first residual effluent stream 133 is introduced into the first residual effluent thickener 150, (3) after 146c the first residual effluent stream 133 has been collected as underflow from the first residual effluent thickener 150, or (4) any combination thereof. After adding one or more additives (146a, 146b, 146c), the first residual effluent stream 134 containing the additives is dewatered using a solid rotor centrifuge 140 to obtain a second cake 136 and a second residual effluent stream 137. The second cake 136 can be collected by any known equipment, such as a conveyor, which can be the same conveyor that is used to collect the first cake 132. The source of additives 145 in some embodiments is a tank containing two or more additives. The additive source 145 in some embodiments includes at least two tanks, each of which contains a different additive, and the different additives can be added independently (1) before 146a the first residual effluent stream 133 is introduced into the first residual effluent thickener 150, (2) simultaneously as 146b the first residual effluent stream 133 is introduced into the first residual effluent thickener 150, (3) after 146c the first residual effluent stream 133 has been collected as an undersize product from the first residual effluent thickener 150, or (4) any combination thereof.

As shown, for example, in Fig. 1A and Fig. 1B, the methods proposed herein may include contacting the first residual effluent stream with one or more additives. Contacting the first residual effluent stream with one or more additives may occur at any point in the method, preferably prior to dewatering the first residual effluent stream using a solid-bore centrifuge.

For example, contacting the first residual effluent stream with one or more additives may occur (1) before introducing the first residual effluent stream into the thickener of the first residual effluent stream and/or (2) after introducing the first residual effluent stream into the thickener of the first residual effluent stream. When the first residual effluent stream is contacted with one or more additives after introducing the first residual effluent stream into the thickener of the first residual effluent stream, contacting the first residual effluent stream with one or more additives may occur (1) simultaneously while the first residual effluent stream is in the thickener of the first residual effluent stream, (2) after the first residual effluent stream exits the thickener of the first residual effluent stream, or (3) a combination thereof. Embodiments of the methods described herein are directed to processing streams; It should therefore be noted that when the first residual effluent is brought into contact with one or more additives at a certain point in the process, such as "before the first residual effluent is introduced into the first residual effluent thickener," the one or more additives come into contact with a portion of the first residual effluent that has not yet been introduced into the first residual effluent thickener.

For example, contacting the first residual effluent with the flocculant may occur (1) before the first residual effluent is introduced into the first residual effluent thickener, (2) simultaneously with the first residual effluent being in the first residual effluent thickener, (3) after the first residual effluent exits the first residual effluent thickener, or (4) a combination thereof.

For example, contacting the first residual effluent with the coagulant may occur (1) prior to introducing the first residual effluent into the first residual effluent thickener, (2) concurrently with the first residual effluent being in the first residual effluent thickener, (3) after the first residual effluent exits the first residual effluent thickener, or (4) a combination thereof.

For example, contacting the first residual effluent stream with the conditioning additive may occur (1) prior to introducing the first residual effluent stream into the first residual effluent thickener, (2) concurrently with the first residual effluent stream being in the first residual effluent thickener, (3) after the first residual effluent stream exits the first residual effluent thickener, or (4) a combination thereof.

For example, contacting the first residual effluent stream with the surfactant may occur (1) prior to introducing the first residual effluent stream into the first residual effluent stream thickener, (2) concurrently with the first residual effluent stream being in the first residual effluent stream thickener, (3) after the first residual effluent stream exits the first residual effluent stream thickener, or (4) a combination thereof.

For example, contacting the first residual effluent stream with the seeding agent may occur (1) prior to introducing the first residual effluent stream into the first residual effluent stream thickener, (2) concurrently with the first residual effluent stream being in the first residual effluent stream thickener, (3) after the first residual effluent stream exits the first residual effluent stream thickener, or (4) a combination thereof.

In some embodiments, the first residual effluent is contacted with (a) a flocculant, (b) a coagulant, or (c) a combination thereof after introducing the first residual effluent into a first residual effluent thickener, such as while the first residual effluent is in the first residual effluent thickener. In some embodiments, the first residual effluent is contacted with a seeding agent after the first residual effluent exits the first residual effluent thickener. In some embodiments, the first residual effluent is contacted with (1) (a) a flocculant, (b) a coagulant, or (c) a combination thereof after introducing the first residual effluent into a first residual effluent thickener, such as while the first residual effluent is in the first residual effluent thickener; and (2) a seeding agent (A) while the first residual effluent stream is in the first residual effluent thickener, (B) after the first residual effluent stream exits the first residual effluent thickener, or (C) a combination thereof.

In some embodiments, the first residual effluent is contacted with (1) (a) a flocculant, (b) a coagulant, or (c) a combination thereof while the first residual effluent is in the first residual effluent thickener, (2) (a) a conditioning additive, (b) a surfactant, or (c) a combination thereof (A) while the first residual effluent is in the first residual effluent thickener, (B) after the first residual effluent exits the first residual effluent thickener, or (C) a combination thereof, (3) a seeding agent (A) while the first residual effluent is in the first residual effluent thickener, (B) after the first residual effluent exits the first residual effluent thickener, or (C) a combination thereof, or (4) a combination thereof.

One or more additives may be provided by one or more feedstocks. The one or more feedstocks may be in communication with one or more additive sources, such as vessels into which one or more additives are introduced. Each of the one or more feedstocks may independently be configured to contact a stream, such as a first residual effluent stream, with one or more additives at any point in the system or method provided herein, such as (1) prior to the introduction of the first residual effluent stream into the thickener of the first residual effluent stream, (2) concurrently with the first residual effluent stream being in the thickener of the first residual effluent stream, or (3) after the first residual effluent stream has exited the thickener of the first residual effluent stream. For example, the system may include three feedstocks, and the first feedstock may be designed to contact the stream with one or more additives before the stream is introduced into the thickener of the first residual effluent stream, and the second and third feedstocks may be designed to contact the stream with one or more additives while the stream is introduced into the thickener of the first residual effluent stream. Other embodiments are also envisaged.

The methods proposed herein may include dewatering a first residual effluent stream using a solid-rotor centrifuge to produce a second cake and a second residual effluent stream. The second residual effluent stream may be introduced into a waste stream thickener and then reprocessed. In some embodiments, providing a tailings stream includes (1) introducing the waste stream and the second residual effluent stream into the waste stream thickener, and (2) collecting the tailings stream from the waste stream thickener.

A schematic embodiment of the method/system is shown in Fig. 2A. In the method/system 200 of Fig. 2, a waste stream 251 is introduced into a waste stream thickener 250. A dilution liquid from a dilution liquid feedstock 252 may be combined with an underflow 253 of the waste stream thickener 250 to produce a tailings stream 201 with a target weight percent solids. The tailings stream 201 is then dewatered by a dewatering device 210 to produce a first residual effluent stream 203 and a first cake 202. The first cake 202 may be collected by any known equipment, such as a conveyor. The first residual effluent stream 203 is then introduced into a first residual effluent thickener 220. In the embodiment shown in Fig. 2A, the first residual effluent stream 203 is contacted with one or more additives from at least one feed (226a, 226b, 226c) in communication with the additive source 225, (1) before (226a) the first residual effluent stream 203 is introduced into the first residual effluent thickener 220, (2) simultaneously as (226b) the first residual effluent stream 203 is introduced into the first residual effluent thickener 220, (3) after (226c) the first residual effluent stream 203 has been collected as underflow from the first residual effluent thickener 220, or (4) any combination thereof. After adding one or more additives (e.g., a flocculant, a coagulant, a conditioning additive, a surfactant, a seeding agent, or a combination thereof), the first residual effluent stream 204 containing the additives is dewatered using a solid rotor centrifuge 230 to produce a second cake 206 and a second residual effluent stream 207. The second residual effluent stream 207 is introduced into a waste stream thickener 250 in the embodiment shown in Fig. 2. The second cake 206 can be collected by any known equipment, such as a conveyor, which can be the same conveyor that is used to collect the first cake 202. The additive source 225 in some embodiments is a tank containing two or more additives. The additive source 225 in some embodiments includes at least two tanks, each of which contains a different additive, and the different additives can be added independently (1) before 226a the first residual effluent stream 203 is introduced into the first residual effluent thickener 220, (2) simultaneously as 226b the first residual effluent stream 203 is introduced into the first residual effluent thickener 220, (3) after 226c the first residual effluent stream 203 has been collected as an undersize product from the first residual effluent thickener 220, or (4) any combination thereof.

In some embodiments, the dewatering device 210 of Fig. 2A may be a solid-rotor centrifuge, and the first residual effluent stream 203 is a centrate from the solid-rotor centrifuge. In some embodiments, the dewatering device 210 of Fig. 2A includes any of the dewatering devices described herein.

A schematic embodiment of the method/system is shown in Fig. 2B. In the method/system 260 of Fig. 2B, a waste stream 261 is introduced into a waste stream thickener 270. A diluent liquid 262 may be combined with the underflow 263 of the waste stream thickener 270 to produce a tailings stream 264 having a target weight percentage of solids. The tailings stream 264 is then dewatered using a solid rotor centrifuge 280 to produce a first residual effluent stream 265 and a first cake 266. The first cake 266 may be collected using any known equipment, such as a conveyor. The first residual effluent stream 265 is then sent to a first residual effluent thickener 290. In the embodiment shown in Fig. 2B, the first residual effluent stream 265 contacts one or more additives from at least one additive feed (286a, 286b, 286c) in communication with the additive source 285, (1) before (286a) the first residual effluent stream 265 is introduced into the first residual effluent thickener 290, (2) simultaneously as (286b) the first residual effluent stream 265 is introduced into the first residual effluent thickener 290, (3) after (286c) the first residual effluent stream 265 has been collected as underflow from the first residual effluent thickener 290, or (4) any combination thereof. After adding one or more additives (e.g., a flocculant, a coagulant, a conditioning additive, a surfactant, a seeding agent, or a combination thereof), the first residual effluent stream 267 containing the additives is dewatered using a solid rotor centrifuge 280 to produce a second cake 268 and a second residual effluent stream 269. The second residual effluent stream 269 is introduced into a waste stream thickener 270 in the embodiment shown in Fig. 2B. The second cake 268 can be collected by any known equipment, such as a conveyor, which may be the same conveyor that is used to collect the first cake 266. The additive source 285, in some embodiments, is a tank containing two or more additives. The additive source 285 in some embodiments includes at least two tanks, each of which contains a different additive, and the different additives can be added independently (1) before 286a the first residual effluent stream 265 is introduced into the first residual effluent thickener 290, (2) simultaneously as 286b the first residual effluent stream 265 is introduced into the first residual effluent thickener 290, (3) after 286c the first residual effluent stream 265 has been collected as an undersize product from the first residual effluent thickener 290, or (4) any combination thereof.

Other dehydration methods and systems

In some embodiments, the methods include providing a tailings stream; contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid bowl centrifuge to obtain a first cake and a first residual effluent. The tailings stream can be any of those described herein. For example, the tailings stream can comprise clay, such as swelling clay, and/or the tailings stream can comprise sludge from a co-utilization site. The tailings stream can have a solids content that (1) is in an amount of from about 10 wt. % to about 40 wt. % by weight of the tailings stream, (2) consists of a collection of particles, wherein at least 25 wt. % or at least 40 wt. % of the particle population is not retained by a 400 mesh woven metal mesh and/or (3) consists of a particle population wherein at least 10 vol. % of the particle population has an average largest dimension of 2 microns or less, or (4) is a combination thereof.

A schematic embodiment of the method/system is shown in Fig. 3. The method/system 300 includes providing a tailings stream 301, contacting the tailings stream 301 with one or more additives from an additive feedstock 303 in communication with an additive source 302, and then dewatering the additive-containing tailings stream 304 using a solid bowl centrifuge 310 to produce a cake 320 and a solid bowl centrifuge centrate 330.

In some embodiments, the methods include providing a tailings stream, wherein the tailings stream has a solids content that (1) is in an amount of from about 10 wt. % to about 30 wt. % by weight of the tailings stream, (2) consists of a population of particles, wherein at least 25 wt. % of the population of particles is not retained by a 400 mesh woven metal screen, and (3) consists of a population of particles, wherein at least 10 vol. % of the population of particles has an average largest dimension of 2 microns or less; contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid rotor centrifuge to obtain a first cake and a first residual effluent. The tailings stream may comprise swelling clay.

IMPLEMENTATION OPTIONS

The following is a non-limiting list of embodiments of the methods and systems described herein:

Embodiment 1, A method for processing a stream, comprising:

(A) providing a tailings stream; dewatering the tailings stream using a dewatering device to produce a first cake and a first residual effluent stream; contacting the first residual effluent stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the first residual effluent stream using a solid rotor centrifuge to produce a second cake and a second residual effluent stream;

(B) providing a tailings stream, the tailings stream having a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream; dewatering the tailings stream with a dewatering device to produce a first cake and a first residual effluent stream, wherein the first residual effluent stream optionally has a solids content of from about 0.2 wt. % to about 15 wt. % by weight of the first residual effluent stream; contacting the first residual effluent stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the first residual effluent stream with a solid rotor centrifuge to produce a second cake and a second residual effluent stream; or

(B) providing a tailings stream, wherein the tailings stream comprises clay, wherein the clay is in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream; dewatering the tailings stream with a dewatering device to produce a first cake and a first residual effluent stream, wherein the first residual effluent stream optionally has a solids content of from about 0.2% by weight to about 15% by weight of the first residual effluent stream; contacting the first residual effluent stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the first residual effluent stream with a solid rotor centrifuge to produce a second cake and a second residual effluent stream; or

(G) providing a tailings stream, wherein the tailings stream (1) has a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream, and

(2) comprises clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream; dewatering the tailings stream with a dewatering device to produce a first cake and a first residual effluent stream, wherein the first residual effluent stream has a solids content of from about 0.2% by weight to about 15% by weight of the first residual effluent stream; contacting the first residual effluent stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the first residual effluent stream with a solid rotor centrifuge to produce a second cake and a second residual effluent stream; or

(D) providing a tailings stream; contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid rotor centrifuge to produce a first cake and a first residual effluent;

(E) providing a tailings stream, wherein the tailings stream has a solids content in an amount of from about 10 wt.% to about 40 wt.% by weight of the tailings stream; contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid rotor centrifuge to produce a first cake and a first residual effluent stream;

(G) providing a tailings stream, wherein the tailings stream has a solids content consisting of a particulate population wherein at least 25% by weight of the particulate population is not retained by a 400 mesh woven metal screen and wherein at least 10% by volume of the particulate population has an average largest dimension of 2 microns or less;

contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid rotor centrifuge to produce a first cake and a first residual effluent; or

(3) providing a tailings stream, wherein the tailings stream has a solids content that—

(1) is present in an amount of from about 10 wt.% to about 40 wt.% by weight of the tailings stream, (2) consists of a population of particles, wherein at least 25 wt.% of the population of particles is not retained by a 400 mesh woven metal screen, wherein at least 10 vol.% of the population of particles has an average largest dimension of 2 microns or less; contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid rotor centrifuge to obtain a first cake and a first residual effluent stream.

Embodiment 2, A flow processing system comprising:

(A) a dewatering apparatus configured to dewater a tailings stream to produce a first cake and a first residual effluent stream; and a solid rotor centrifuge configured to dewater the first residual effluent stream to produce a second cake and a second residual effluent stream; or

(B) a dewatering apparatus configured to dewater a tailings stream to produce a first cake and a first residual effluent stream, wherein the tailings stream has a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream, and wherein the first residual effluent stream has a solids content of from about 0.2 wt. % to about 15 wt. % by weight of the first residual effluent stream; and a solid rotor centrifuge configured to dewater the first residual effluent stream to produce a second cake and a second residual effluent stream; or

(B) a dewatering apparatus configured to dewater a tailings stream to produce a first cake and a first residual effluent stream, wherein the tailings stream comprises clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream; and a solid rotor centrifuge configured to dewater the first residual effluent stream to produce a second cake and a second residual effluent stream; or

(D) a dewatering device configured to dewater a tailings stream to produce a first cake and a first residual effluent stream, wherein the tailings stream (1) has a solids content of from about 2 wt. % to about 40 wt. % by weight of the tailings stream, and (2) contains clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream,

wherein the first residual effluent stream has a solids content of from about 0.2 wt.% to about 15 wt.%, based on the weight of the first residual effluent stream; and a solid rotor centrifuge configured to dewater the first residual effluent stream to produce a second cake and a second residual effluent stream; or

(D) one or more additive feedstocks configured to contact the tailings stream with one or more additives; and a solid rotor centrifuge configured to dewater the tailings stream to produce a first cake and a first residual effluent stream.

Embodiment 3, The method or system of any of the preceding embodiments, wherein the clay comprises a swelling clay, a non-swelling clay, or a combination thereof.

Embodiment 4, The method or system of any of the preceding embodiments, wherein (1) the swelling clay is in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, (2) the non-swelling clay is in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, or (3) a combination thereof.

Embodiment 5, The method or system of any of the preceding embodiments, further comprising introducing the first residual effluent into a first residual effluent thickener prior to dewatering the first residual effluent with a solid rotor centrifuge, wherein the first residual effluent thickener increases the solids content of the first residual effluent by about 1 to about 40 weight percentage points.

Embodiment 6, The method or system of any of the preceding embodiments, wherein contacting the first residual effluent stream with one or more additives occurs before introducing the first residual effluent stream into a first residual effluent stream thickener.

Embodiment 7, The method or system of any of the preceding embodiments, wherein contacting the first residual effluent stream with one or more additives occurs after introducing the first residual effluent stream into a first residual effluent stream thickener.

Embodiment 8, The method or system of any of the preceding embodiments, wherein contacting the first residual effluent stream with one or more additives occurs (1) while the first residual effluent stream is in the first residual effluent thickener, (2) after the first residual effluent stream exits the first residual effluent thickener, or (3) a combination thereof.

Embodiment 9, The method or system of any of the preceding embodiments, wherein the first residual effluent stream is contacted with -

(1) (a) a flocculant, (b) a coagulant, or (c) a combination thereof, while the first residual effluent stream is in a first residual effluent thickener,

(2) (a) a conditioning additive, (b) a surfactant, or (c) a combination thereof (A) while the first residual effluent stream is in the first residual effluent thickener, (B) after the first residual effluent stream has exited the first residual effluent thickener, or (C) a combination thereof,

(3) the seeding agent (1) while the first residual effluent is in the first residual effluent thickener, (2) after the first residual effluent exits the first residual effluent thickener, or (3) a combination thereof, or

(4) a combination of them; or

wherein the first residual effluent is contacted with one or more additives according to embodiments a-u from the following Table:

A - The said additive is brought into contact with the first residual effluent stream "before the first residual effluent stream is introduced into the first residual effluent stream thickener."

B - The said additive is brought into contact with the first residual effluent stream "simultaneously with the first residual effluent stream being in the first residual effluent stream thickener."

B - The said additive is brought into contact with the first residual effluent stream "after the first residual effluent stream exits the first residual effluent stream thickener."

Embodiment 10. The method or system of any of the preceding embodiments, wherein providing a tailings stream comprises: (1) introducing the waste stream into a waste stream thickener; and (2) collecting the tailings stream from the waste stream thickener.

Embodiment 11. The method or system of any of the preceding embodiments, further comprising, after collecting the tailings stream, diluting the tailings stream with an amount of liquid sufficient to provide the tailings stream with a solids content of from about 10 wt.% to about 40 wt.%, based on the weight of the tailings stream.

Embodiment 12. The method or system of any of the preceding embodiments, further comprising introducing the second residual effluent stream into a waste stream thickener.

Embodiment 13. The method or system of any of the preceding embodiments, wherein the first residual effluent stream comprises a first centrate from a solid rotor centrifuge.

Embodiment 14. The method or system of any of the preceding embodiments, wherein the first cake comprises from about 60 wt.% to about 99 wt.% of the solids content of the tailings stream.

Embodiment 15. The method or system of any of the preceding embodiments, wherein the first cake comprises from about 60 wt.% to about 90 wt.% of the solids content of the tailings stream.

Embodiment 16. The method or system of any of the preceding embodiments, wherein the first cake has a water content of from about 20 wt.% to about 45 wt.%, based on the weight of the first cake.

Embodiment 17. The method or system of any of the preceding embodiments, wherein the total amount of solids present in the first cake and the second cake is at least 90 wt.% of the solids content of the tailings stream.

Embodiment 18. The method or system of any of the preceding embodiments, wherein the total amount of solids present in the first cake and the second cake is at least 95 wt.% of the solids content of the tailings stream.

Embodiment 19. The method or system of any of the preceding embodiments, wherein the total amount of solids present in the first cake and the second cake is at least 99 wt.% of the solids content of the tailings stream.

Embodiment 20. The method or system of any of the preceding embodiments, wherein the first residual effluent stream is contacted with a flocculant in an amount of from about 1 gram to about 150 grams of flocculant per ton of dry matter content of the tailings stream.

Embodiment 21. The method or system of any of the preceding embodiments, wherein the first residual effluent stream is contacted with a flocculant in an amount of from about 1 gram to about 50 grams of flocculant per ton of dry matter content of the tailings stream.

Embodiment 22. The method or system of any of the preceding embodiments, wherein the flocculant comprises a non-ionic flocculant.

Embodiment 23. The method or system of any of the preceding embodiments, wherein the flocculant comprises an anionic flocculant or a cationic flocculant.

Embodiment 24. The method or system of any of the preceding embodiments, wherein the flocculant is in powder form prior to contacting the first residual effluent stream with the flocculant, and the method further comprises: (A) optionally adjusting the pH of the aqueous liquid and introducing the powder into the aqueous liquid prior to contacting the first residual effluent stream with one or more additives; or (B) providing an aqueous liquid into which the powder is introduced.

Embodiment 25. The method or system of any of the preceding embodiments, wherein the flocculant is a high molecular weight polymeric flocculant or a very high molecular weight polymeric flocculant.

Embodiment 26. The method or system of any one of the preceding embodiments, wherein (1) the flocculant is selected from the group consisting of NALCO™ 749222 flocculant, YONGXING™ YX1224-6 flocculant, YONGXING™ PAM flocculant, YIXING™ ARAM01 flocculant, ULTRACLEAR™ ProFlocculant™ flocculant, GLORY™ flocculant, ZETAG™ 8127 flocculant (BASF, USA), ZETAG™ 4145 flocculant (BASF, USA), MAGNAFLOC® LT20 flocculant (BASF, USA), MAGNAFLOC® 338 flocculant (BASF, USA), MAGNAFLOC® flocculant 10 (BASF, USA), flocculant MAGNAFLOC® 155 (BASF, USA), flocculant MAGNAFLOC® 1011 (BASF, USA), flocculant MAGNAFLOC® 5250 (BASF, USA), flocculant MAGNAFLOC® 336 (BASF, USA), flocculant MAGNAFLOC® 919 (BASF, USA), flocculant RHEOMAX® 1050 (BASF, USA), flocculant MAGNAFLOC® 10 (BASF, USA), flocculant MAGNAFLOC® 155 (BASF, USA), flocculant MAGNAFLOC® 1011 (BASF, USA), flocculant MAGNAFLOC® 5250 (BASF, USA), flocculant MAGNAFLOC® 336 (BASF, USA), flocculant MAGNAFLOC® 919 (BASF, USA), flocculant RHEOMAX® ETD 9010 (BASF, USA), polyacrylamide flocculant MAGNAFLOC® LT27AG (BASF, USA), acrylic homopolymer flocculant ZETAG™ 7109 (BASF, USA), flocculant MAGNAFLOC® 333 (BASF, USA), flocculant FLOBEADS® KB206SH (SNF, UK), flocculant FLOBEADS® KB156 (SNF, UK), flocculant FLOPAM® FO4190 (SNF, UK), flocculant FLOPAM® FO4140 (SNF, UK), flocculant FLOQUAT® TS 45 SH (SNF, UK), flocculant FLOPAM® FA920VHM (SNF, UK), flocculant FLOPAM® FA920VHR (SNF, UK), flocculant FLOPAM® FA920SD (SNF, UK), flocculant FLOPAM® FA920SHD (SNF, UK), flocculant FLOPAM® FA920 (SNF, UK), flocculant ALCLAR® 5000 (BASF, USA), flocculant ALCLAR® 600 (BASF, USA), flocculant ALCLAR® 661 (BASF, USA), flocculant ALCLAR® HP20 (BASF, USA), flocculant ALCLAR® HP21 (BASF, USA), flocculant ALCLAR® HP22 (BASF, USA), flocculant DRIMAX® 1235 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1238 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1240 (Allied Colloids Ltd., UK), flocculant LUPROMIN® F-20X (BASF, USA), flocculant LUPROMIN® FP 18 AS (BASF, USA), LUPROMIN® FP 199 (BASF, USA), flocculant HI-TEX® 82230 (Hi-Tex Corp, USA), and combinations thereof, (2) the coagulant is selected from the group consisting of coagulant MAGNAFLOC® LT7991 (BASF, USA), coagulant MAGNAFLOC® LT32 (BASF, USA), coagulant MAGNAFLOC® LT38 (BASF, USA), coagulant MAGNAFLOC® 1425 (BASF, USA), coagulant FLOQUAT® FL2549SEP (SNF, UK), FLOQUAT® FLB1725SEP (SNF, UK), FLOQUAT® FL5323 (SNK, UK) and combinations thereof, or (3) combinations thereof.

Embodiment 27. The method or system of any of the preceding embodiments, wherein the swelling clay comprises illite-smectite, smectite, montmorillonite, or a combination thereof.

Embodiment 28. The method or system of any of the preceding embodiments, wherein the non-swelling clay comprises kaolinite, illite, or a combination thereof.

Embodiment 29. The method or system of any of the preceding embodiments, wherein the swelling clay is present in the tailings stream in an amount of from about 0.5% to about 50% by absolute content of the solids content of the tailings stream.

Embodiment 30. The method or system of any of the preceding embodiments, wherein the dewatering device comprises a belt press filter, a horizontal belt vacuum filter, a rotary vacuum drum filter, a rotary vacuum disc filter, a mesh centrifuge, a steep cone paste thickener, a membrane filter press, a solid rotor centrifuge, or an additional solid rotor centrifuge.

Embodiment 31. The method or system of any of the preceding embodiments, wherein the dewatering device is a solid rotor centrifuge.

Embodiment 32. The method or system of any of the preceding embodiments, wherein the tailings stream comprises (1) coal beneficiation plant tailings, (2) phosphate beneficiation plant tailings, (3) XX settling basin tailings, (4) XX tailings, or (5) a combination thereof.

Embodiment 33. The method or system of any of the preceding embodiments, wherein the solids content of the tailings stream is from about 2 wt. % to about 35 wt. %, from about 2 wt. % to about 30 wt. %, from about 2 wt. % to about 25 wt. %, from about 2 wt. % to about 20 wt. %, from about 2 wt. % to about 15 wt. %, from about 10 wt. % to about 35 wt. %, from about 10 wt. % to about 25 wt. %, from about 15 wt. % to about 30 wt. %, from about 15 wt. % to about 25 wt. %, by weight of the tailings stream.

Embodiment 34. The method or system of any of the preceding embodiments, wherein the tailings stream comprises a mineral residue of from about 10 wt.% to about 80 wt.%, from about 10 wt.% to about 70 wt.%, from about 10 wt.% to about 60 wt.%, from about 10 wt.% to about 50 wt.%, from about 15 wt.% to about 50 wt.%, from about 15 wt.% to about 40 wt.%, from about 20 wt.% to about 40 wt.%, or from about 30 wt.% to about 40 wt.%, based on the weight solids content of the tailings stream.

Embodiment 35. The method or system of any of the preceding embodiments, wherein the percent, by weight, of solids content in the tailings stream that is not retained by the 60 mesh woven metal screen is from about 50% to 100%, from about 60% to 100%, from about 65% to 100%, from about 70% to 100%, from about 75% to 100%, from about 80% to 100%, from about 85% to 100%, or from about 90% to 100%.

Embodiment 36. The method or system of any of the preceding embodiments, wherein the percentage, by weight, of solids content in the tailings stream that is not retained by the 400 mesh woven metal mesh is from about 25% to 80%, from about 25% to 70%, from about 25% to 70%, from about 50% to 80%, from about 50% to about 70%, or from about 60% to about 70%.

Embodiment 37. The method or system of any of the preceding embodiments, wherein the tailings stream is contacted with a flocculant in an amount of from about 250 grams to about 500 grams per ton of dry matter content of the tailings stream, or about 400 grams per ton of dry matter content of the tailings stream.

Embodiment 38. The method or system of any of the preceding embodiments, wherein the total amount of solids present in the first cake is from about 65 wt.% to about 99 wt.%, from about 65 wt.% to about 90 wt.%, from about 70 wt.% to about 90 wt.%, or from about 75 wt.% to about 85 wt.% of the solids content of the tailings stream.

Embodiment 39. The method or system of any of the preceding embodiments, wherein the first cake has a water content of from about 15 wt.% to about 40 wt.%, based on the weight of the first cake.

Embodiment 40. The method or system of any of the preceding embodiments, wherein the first cake has a water content of from about 30 wt.% to about 40 wt.%, based on the weight of the first cake.

Embodiment 41. The method or system of any of the preceding embodiments, wherein (1) at least 30 wt.%, at least 40 wt.%, at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, or at least 90 wt.% of the particle population is not retained by a 400 mesh woven metal mesh, (2) at least 20 vol.%, at least 30 vol.%, at least 40 vol.%, at least 50 vol.%, at least 60 vol.%, at least 70 vol.%, at least 80 vol.%, or at least 90 vol.% of the particle population has an average largest dimension of 2 microns or less.

Embodiment 42. The system of any one of the preceding embodiments, further comprising a waste stream thickener configured to produce an undersize product comprising a tailings stream.

Embodiment 43. The system of any of the preceding embodiments further comprising a liquid feedstock configured to dilute the tailings stream with the liquid prior to dewatering the tailings stream.

Embodiment 44. The system of any one of the preceding embodiments, further comprising a first residual effluent thickener located between the dewatering device and the solid rotor centrifuge, wherein the first residual effluent thickener is configured to increase the solids content of the first residual effluent by from about 1 to about 40 weight percentage points.

Embodiment 45. The system of any one of the preceding embodiments, further comprising one or more additive feedstocks, wherein each of the one or more additive feedstocks is independently configured to contact the first residual effluent stream with one or more additives (1) before the first residual effluent stream is introduced into the first residual effluent thickener, (2) simultaneously as the first residual effluent stream is introduced into the first residual effluent thickener, or (3) after the first residual effluent stream exits the first residual effluent thickener.

Embodiment 46. The system of any of the preceding embodiments, further comprising a conveyor configured to collect the first cake, the second cake, or both the first cake and the second cake.

Embodiment 47. The system or method of any one of the preceding embodiments, wherein the one or more additives comprise a flocculant, and the first residual effluent stream is contacted with the flocculant in an amount of from about 1 gram to about 500 grams, from about 100 grams to about 500 grams, from about 200 grams to about 500 grams, from about 250 grams to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, from about 1 gram to about 50 grams, from about 1 gram to about 40 grams, from about 1 gram to about 30 grams, from about 1 gram to about 20 grams, or from about 1 gram to about 10 grams of flocculant per ton of dry matter content of the tailings stream.

Embodiment 48. The system or method of any of the preceding embodiments, wherein the one or more additives comprise a coagulant, and the first residual effluent stream is contacted with the coagulant in an amount of from about 1 gram to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, or from about 1 gram to about 50 grams of coagulant per ton of dry solids content of the tailings stream.

Embodiment 49. The system or method of any of the preceding embodiments, wherein the weight ratio of solids to seeding agent contacted with the first residual effluent stream is from about 0.7:1 to about 1:0.7, from about 0.8:1 to about 1:0.8, from about 0.9:1 to about 1:0.9, from about 0.95:1 to about 1:0.95, from about 0.99:1 to about 1:0.99, or about 1:1.

Embodiment 50. The system or method of any one of the preceding embodiments, wherein the first residual effluent stream, after being "thickened" by the thickener of the first residual effluent stream, has a solids content of from about 1.2 wt. % to about 55 wt. %, from about 1.2 wt. % to about 54 wt. %, from about 1.2 wt. % to about 53 wt. %, from about 1.2 wt. % to about 52 wt. %, from about 1.2 wt. % to about 51 wt. %, from about 1.2 wt. % to about 50 wt. %, from about 1.2 wt. % to about 49 wt. %, from about 1.2 wt. % to about 48 wt. %, from about 1.2 wt. % to about 47 wt. %, from about 1.2 wt. % to about 46 wt. %, from about 1.2 wt. % to about 45 wt. %, from about 1.2 wt. % to about 44 wt. %, from about 1.2 wt. % to about 43 wt. %, from about 1.2 wt. % to about 42 wt. %, from about 1.2 wt. % to about 41 wt. %, from about 1.2 wt. % to about 30 wt. %, from about 1.2 wt. % to about 29 wt. %, from about 1.2 wt. % to about 28 wt. %, from about 1.2 wt. % to about 27 wt. %, from about 1.2 wt. % to about 26 wt. %, from about 10 wt. % to about 35 wt. %, from about 10 wt. % to about 34 wt. %, from about 10 wt. % to about 33 wt. %, from about 10 wt. % to about 32 wt. %, from about 10 wt. % to about 31 wt. %, from about 10 wt. % to about 30 wt. %, from about 10 wt. % to about 29 wt. %, from about 10 wt. % to about 28 wt. %, from about 10 wt. % to about 27 wt. %, from about 10 wt. % to about 26 wt. %, from about 20 wt. % to about 35 wt. %, about 20 wt. % to about 34 wt. %, from about 20 wt. % to about 33 wt. %, from about 20 wt. % to about 32 wt. %, from about 20 wt. % to about 31 wt. %, from about 20 wt. % to about 30 wt. %, from about 20 wt. % to about 29 wt. %, from about 20 wt. % to about 28 wt. %, from about 20 wt. % to about 27 wt. %, from about 20 wt. % to about 26 wt. %, from about 25 wt. % to about 35 wt. %, from about 25 wt. % to about 34 wt. %, from about 25 wt. % to about 33 wt. %, from about 25 wt. % to about 32 wt. %, from about 25 wt. % to about 31 wt. %, from about 25 wt. % to about 30 wt. %, from about 25 wt. % to about 29 wt. %, from about 25 wt. % to about 28 wt. %, from about 25 wt. % to about 27 wt. %, or from about 25 wt. % to about 26 wt. %, based on the weight of the first residual effluent stream.

Embodiment 51. The system or method of any one of the preceding embodiments, wherein (1) the amount of suspended solids in the second residue effluent stream is from about 10 mg/L to about 750 mg/L, from about 10 mg/L to about 700 mg/L, from about 10 mg/L to about 650 mg/L, from about 10 mg/L to about 600 mg/L, from about 10 mg/L to about 550 mg/L, from about 10 mg/L to about 500 mg/L, from about 10 mg/L to about 450 mg/L, from about 10 mg/L to about 400 mg/L, from about 10 mg/L to about 350 mg/L, from about 10 mg/L to about 300 mg/L, from about 10 mg/L to about 250 mg/L, from about 10 mg/L to about 200 mg/L, from about 10 mg/L to about 150 mg/L, or from about 10 mg/L to about 100 mg/L, (2) the second residual effluent stream has a turbidity of from about 10 NEF to about 100 NEF, from about 10 NEF to about 75 NEF, from about 10 NEF to about 50 NEF, or from about 10 NEF to about 25 NEF, (3) the second residual effluent stream contains water in an amount of at least 95 wt. %, 98 wt. %, or 99 wt. % of the second residual effluent stream, or (4) a combination thereof.

Embodiment 52. The system or method of any of the preceding embodiments, wherein the conditioning additive is selected from the group consisting of a metal halide, a metal sulfate, a metal hydroxide, and a combination thereof, wherein the metal halide may include a metal chloride such as magnesium chloride, iron chloride, sodium chloride, etc.; the metal sulfate may include magnesium sulfate, aluminum sulfate, potassium sulfate, etc.; and the metal hydroxide may include calcium hydroxide (e.g., slaked lime).

Embodiment 53. The system or method of any of the preceding embodiments, wherein the one or more additives comprise a conditioning additive, a surfactant, or a combination thereof, and the first residual effluent stream is contacted with the conditioning additive or surfactant in an amount of from about 1 gram to about 5,000 grams, from about 1 gram to about 4,000 grams, from about 1,000 grams to about 4,000 grams, from about 1,000 grams to about 3,000 grams, or about 2,000 grams of conditioning additive or surfactant per ton of dry matter content in the tailings stream, wherein optionally the amount of conditioning additive and/or surfactant can be selected to achieve a target cation concentration.

Embodiment 54. The system or method of any one of the preceding embodiments, wherein the one or more additives comprise a flocculant and a seeding agent, and the first residual effluent stream is contacted with the flocculant in an amount of from about 1 gram to about 500 grams, from about 100 grams to about 500 grams, about 200 grams to about 500 grams, from about 250 grams to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, from about 1 gram to about 50 grams, from about 1 gram to about 40 grams, from about 1 gram to about 30 grams, from about 1 gram to about 20 grams, or from about 1 gram to about 10 grams, or about 50 grams of flocculant per ton of dry matter content in the tailings stream; and the weight ratio of the solids content to the amount of seeding agent contacted with the first residual effluent stream is from about 0.7:1 to about 1:0.7, from about 0.8:1 to about 1:0.8, from about 0.9:1 to about 1:0.9, from about 0.95:1 to about 1:0.95, from about 0.99:1 to about 1:0.99, or about 1:1.

Embodiment 55. The system or method of any one of the preceding embodiments, wherein the one or more additives comprise a flocculant and a conditioning additive, and the first residual effluent stream is contacted with the flocculant in an amount of from about 1 gram to about 500 grams, from about 100 grams to about 500 grams, from about 200 grams to about 500 grams, from about 250 grams to about 500 grams, from about 1 gram to about 400 grams, from about 1 gram to about 300 grams, from about 1 gram to about 200 grams, from about 1 gram to about 150 grams, from about 1 gram to about 100 grams, from about 1 gram to about 75 grams, from about 1 gram to about 50 grams, from about 1 grams to about 40 grams, from about 1 gram to about 30 grams, from about 1 gram to about 20 grams, or from about 1 gram to about 10 grams, or about 50 grams of flocculant per ton of dry matter content of the tailings stream; and the first residual effluent stream is contacted with a conditioning additive in an amount of from about 1 gram to about 5,000 grams, from about 1 gram to about 4,000 grams, from about 1,000 grams to about 4,000 grams, from about 1,000 grams to about 3,000 grams, or about 2,000 grams of conditioning additive per ton of dry matter content of the tailings stream.

Although some aspects of conventional technologies have been discussed to facilitate the disclosure of various embodiments, applicants in no way renounce these technical aspects, and it is intended that the present disclosure may cover one or more of the conventional technical aspects discussed herein.

The present disclosure may address one or more problems and disadvantages of known methods and processes. However, it is contemplated that various embodiments may prove useful in addressing other problems and disadvantages in a variety of technical fields. Therefore, the present disclosure should not necessarily be construed as limited to solving any specific problems or disadvantages discussed herein.

In this description, where a document, act or element of knowledge is referred to or discussed, this reference or discussion does not constitute an admission that the document, act or element of knowledge, or any combination thereof, was, at the priority date, generally known, formed part of the common knowledge, or otherwise constituted prior art under applicable statutory provisions; or was known to be relevant to an attempt to solve any problem to which this description relates.

In the descriptions provided herein, the terms "includes," "is," "comprising," "having," and "contains" are used in an open sense and, thus, should be interpreted to mean "including, but not limited to." When methods or systems are claimed or described as "comprising" various steps or components, the methods or systems may also "consist essentially of" or "consist of" the various steps or components, unless otherwise specified.

Singular nouns are intended to include plural alternatives, such as at least one. For example, the disclosure of "tailings stream," "swelling clay," "flocculant," "coagulant," "conditioning additive," "surfactant," "seeding agent," and the like is intended to include one or mixtures or combinations of more than one tailings stream, swelling clay, flocculant, coagulant, conditioning additive, surfactant, seeding agent, and the like, unless otherwise specified.

Various numerical ranges may be disclosed herein. When the applicant discloses or claims a range of any type, the applicant's intent is to individually disclose or claim every possible number that could reasonably be encompassed by such a range, including the endpoints of the range, as well as any subranges and combinations of subranges encompassed by the range, unless otherwise specified. Furthermore, all numerical endpoints of the ranges disclosed herein are approximate. As a representative example, the applicant discloses in some embodiments that the first cake has a water content of from about 30 wt.% to about 40 wt.%, based on the weight of the first cake. This range should be interpreted as encompassing about 30% and about 40%, and further including each of "about" 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, or 39%, including any ranges and subranges between any of these values.

As used herein, the term "about" means plus or minus 10% of the numerical value of the number with which it is used.

EXAMPLES

The present invention is further illustrated by the following examples, which should in no way be construed as limiting its scope. On the contrary, it should be clearly understood that various other aspects, embodiments, modifications, and equivalents thereof may occur to those skilled in the art upon reading this description, without departing from the spirit of the present invention or the scope of the appended claims. Thus, other aspects of this invention will be apparent to those skilled in the art from consideration of the description and practice of the invention described herein.

Example 1 - Dewatering of Tailings with Swelling Clays The tailings streams of this example, despite the presence of swelling clay, were dewatered to an overall solids recovery of at least 99 wt.%, producing cakes having a water content of about 30 wt.%.

The tailings streams dewatered in this example had the following characteristics:

The tailings streams in this example were dewatered using a solid-rotor centrifuge. The first dewatering run through the solid-rotor centrifuge produced the first cake and the first centrate stream from the solid-rotor centrifuge.

The first cake had a total water content of between about 28% and about 34% by weight of the first cake mass. The first cake of this example was collected by a conveyor.

The first centrate stream from the solid rotor centrifuge had a solids content of from about 2 wt.% to about 7.5 wt.% of the mass of the first centrate stream from the solid rotor centrifuge.

Dewatering the tailings streams through the first solid-rotor centrifuge increased the relative mineral content of kaolinite and illite-smectite clays in the first centrate streams from the solid-rotor centrifuge, with most of the remaining minerals ending up in the centrifuge cake. The increase in relative mineral content in clays was likely due to the fact that clays typically have a particle size of 2 microns or less, allowing the concentrating effect to occur, at least in part, due to particle size.

This conclusion was based on the following characterization of the mineral content in the tailings streams and the centrate stream from a solid rotor centrifuge. The results in the following table are based on relative mineral content and normalized based on the removal of all amorphous carbon from the coal tailings stream.

The centrifuge effluent, which contained a relatively higher percentage of kaolinite and illite-smectite type clays, was then sent to a thickening unit.

After passing through the thickening unit, the first centrate stream from the solid bowl centrifuge was contacted with a flocculant at a rate of approximately 420 grams of active flocculant per ton of dry solids in the tailings stream (i.e., per ton of dry solids content in the tailings stream) fed to the first solid bowl centrifuge. The flocculant used in this example was a commercial product, MAGNAFLOC® 333 flocculant (BASF, USA), which is a high-molecular-weight, non-ionic powder flocculant, but the use of other flocculants is contemplated. The flocculant powder was added to water and allowed to dissolve, after which the pH of the solution was at least 8, before being added to the first residual effluent stream.

Although in this example no flocculant was added prior to use of the thickener, flocculant may be added prior to use of the thickener as a replacement for or in addition to the dosage of undersize product from the thickener.

The thickening device increased the mass percentage of solids in the first centrate stream from the solid rotor centrifuge to about 10 wt. % of the mass of the first centrate stream from the solid rotor centrifuge.

The first centrate stream from the solid-bowl centrifuge was then dewatered in a second pass through the solid-bowl centrifuge. In this example, the second pass through the solid-bowl centrifuge produced a second cake with a water content ranging from about 44% by weight to about 56% by weight of the second cake. The second cake was collected using the conveyor used to collect the first cake.

The first and second cakes contained greater than 99% by weight of dry solids contained in the tailings streams. In other words, the process in this example achieved a solids recovery rate, by weight, of greater than 99%.

The first and second cakes were combined to produce a combined cake with a water content of approximately 35% by weight of the combined cake. In other words, the method in this example produced a combined cake with a water content of approximately 35% by weight of the combined cake.

For comparison purposes, the tailings streams in this example were dewatered using several different methods.

In the first comparative method, tailings streams were contacted with a flocculant and then dewatered using a solid-rotor centrifuge. To achieve a solids recovery of at least 90% by weight of dry solids in the tailings streams, the tailings streams were contacted with a significant amount of flocculant. For example, when the tailings streams were contacted with the flocculant in this example at a rate of at least 600 grams of active flocculant per ton of dry solids, the solids recovery by weight exceeded 95%.

This result, however, was accompanied by at least one of three drawbacks. First, the amount of flocculant required significantly increased the cost of the process. Second, as the amount of flocculant used in the process increased, the water content in the cake also increased. For example, the cake had a water content exceeding 40% by weight of the cake mass when the amount of flocculant used was 600 grams or more of active flocculant per ton of dry solids in the tailings stream. Third, as the amount of flocculant used in the process increased, stackability and processability significantly deteriorated.

The amount of flocculant required in the example, in which the flocculant was applied to the thickened centrate stream from a solid-bowl centrifuge, was 30% lower than in the first comparative method, in which the flocculant was applied to the entire initial tailings stream fed to the solid-bowl centrifuge. These disadvantages were significantly reduced in the method of this example.

Example 2 - Dewatering of Tailings with Swelling Clays Using the Reprocessing and Seeding Method

The tailings streams from this example, despite the presence of swelling clay, were dewatered with an overall solids recovery of at least 99 wt.%, producing cakes having a water content of about 30 wt.%.

The tailings streams dewatered in this example had the following characteristics:

The tailings streams in this example were dewatered using a solid-rotor centrifuge. The first dewatering run through the solid-rotor centrifuge produced the first cake and the first centrate stream from the solid-rotor centrifuge.

The first cake had a total water content of between approximately 28% and approximately 30% by weight of the first cake mass. The first cake in this example was collected by a conveyor.

The first centrate stream from the solid rotor centrifuge had a solids content of up to and including about 5 wt.% of the mass of the first centrate stream.

Dewatering the tailings streams using the first solid-rotor centrifuge increased the relative mineral content of kaolinite and illite-smectite clays in the first centrate stream, with most of the remaining minerals ending up in the centrifuge cake. The increase in relative mineral content in clays was likely due to the fact that clays typically have a particle size of 2 microns or less, allowing the concentrating effect to occur, at least in part, due to particle size.

This conclusion was based on the following characterization of the mineral content in the tailings streams and the first centrate stream from a solid-bore centrifuge. The results in the following table are based on relative mineral content and normalized to the removal of all amorphous carbon.

The first centrate stream from the solid rotor centrifuge, which contained a relatively higher percentage of kaolinite and illite-smectite type clays, was then sent to a thickening device.

After passing through the thickening unit, the first centrate stream from the solid bowl centrifuge was contacted with a flocculant at a rate of approximately 50 grams of active flocculant per ton of dry tailings solids in the tailings stream fed to the first solid bowl centrifuge. The flocculant used in this example was a commercial product: MAGNAFLOC® 333 flocculant (BASF, USA), which is a non-ionic, high-molecular-weight powdered flocculant, but the use of other flocculants is contemplated.

The thickening device increased the mass percentage of solids in the first centrate stream from the solid rotor centrifuge to about 10 wt%.

The first centrate stream from the solid-bore centrifuge was then contacted with a seeding agent. The seeding agent in this example contained particles ranging in size from 250 to 1000 microns and was added in a weight ratio of 1:1 (the dry solids content of the first centrate stream from the solid-bore centrifuge).

The first centrate stream from the solid-bore centrifuge was then dewatered in a second pass through the solid-bore centrifuge. In this example, the solid-bore centrifuge produced a second cake with a water content ranging from about 32% by weight to about 44% by weight of the second cake. The second cake was collected using the conveyor used to collect the first cake.

The first and second cakes contained greater than 99% by weight of the dry solids contained in the tailings streams. In other words, in this example, the process yielded a dry solids recovery of greater than 99% by weight.

The first and second cakes were combined to produce a combined cake with a water content of approximately 30% by weight of the combined cake. In other words, in this example, the method produced a combined cake with a water content of approximately 30% by weight of the combined cake.

For comparison purposes, the tailings streams in this example were dewatered using several different methods.

In the first comparative method, all feedstock tailings streams were contacted with a flocculant and then dewatered using a solid-rotor centrifuge. To achieve a solids recovery of at least 90% by weight of dry solids in the tailings streams, the tailings streams were contacted with a significant amount of flocculant. For example, when the tailings streams were contacted with the flocculant in this example at a rate of at least 600 grams of active flocculant per ton of dry solids in the feedstock tailings streams, the solids recovery by weight exceeded 95%.

This result, however, was accompanied by at least one of three drawbacks. First, the amount of flocculant required significantly increased the cost of the process. Second, as the amount of flocculant used in the process increased, the water content in the cake also increased. For example, the cake had a water content exceeding 40% by weight of the cake mass when the amount of flocculant used was 600 grams or more of active flocculant per ton of dry solids in the tailings stream. Third, as the amount of flocculant used in the process increased, stackability and processability significantly deteriorated.

The amount of flocculant required in the example, in which the flocculant was applied to the thickened centrifuge centrifuge stream, was 92% lower than the amount used in the first comparative method, in which the flocculant was applied to the entire initial tailings stream. All of the above-mentioned disadvantages were overcome in the method of this example.

Example 3 - Dewatering of tailings with sludge from the XX settling area

The tailings streams from this example, although they contained ultrafine particles (i.e., not retained by a 325 mesh screen) and clays, were dewatered to produce cakes with water contents ranging from about 30 wt.% to about 35 wt.%.

The tailings streams dewatered in this example had the following characteristics:

The tailings streams in this example were contacted with flocculant in amounts ranging from about 300 grams of active flocculant to about 500 grams of active flocculant per ton of dry solids in the tailings stream, and, in some cases, about 400 grams of active flocculant per ton of dry solids in the tailings stream. The flocculant used in this example was a high-molecular-weight powder flocculant, but other flocculants, including commercial flocculants, are contemplated.

After contact with the flocculant, the tailings streams in this example were dewatered using a solid rotor centrifuge to produce a cake.

The cakes had a water content ranging from about 30 wt.% to about 35 wt.% of the cake mass.

The cakes in this example had dry solids content ranging from about 70 wt.% to about 90 wt.% in tailings streams.

The cakes in this example demonstrated acceptable processability properties, for example, the cakes could be transported by trucks and disposed of in a specially designated disposal area.

Claims (96)

1. A method for processing a stream, including: - provision of a tailings flow, while the tailings flow (1) has a solids content of 2 to 40 wt.% of the tailings stream and (2) contains clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, wherein said clay contains swelling clay; - dewatering the tailings stream using a dewatering device to obtain a first cake and a first residual effluent stream, wherein the first residual effluent stream has a solids content of from 0.2 to 15 wt.% of the weight of the first residual effluent stream; - contacting the first residual effluent with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and - dewatering the first residual effluent using a solid rotor centrifuge to obtain a second cake and a second residual effluent, wherein said dewatering device includes a belt press filter, a horizontal belt vacuum filter, a rotary vacuum drum filter, a rotary vacuum disc filter, a mesh rotor centrifuge, a thickening device, a membrane filter press, a solid rotor centrifuge, or an additional solid rotor centrifuge. 2. The method according to claim 1, characterized in that said swelling clay is present in the tailings stream in an amount of at least 1% by absolute content of the solids content in the tailings stream. 3. The method of claim 1, wherein (1) the swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, (2) the clay further comprises a non-swelling clay, wherein the non-swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, or (3) a combination thereof. 4. The method of any one of claims 1 to 3, further comprising introducing the first residual effluent into a first residual effluent thickener prior to dewatering the first residual effluent with a solid rotor centrifuge, wherein the first residual effluent thickener increases the solids content of the first residual effluent by from 1 to 40 mass percentage points. 5. The method according to claim 4, characterized in that contacting the first residual effluent with one or more additives occurs before introducing the first residual effluent into the first residual effluent thickener. 6. The method according to claim 4, characterized in that contacting the first residual effluent with one or more additives occurs after introducing the first residual effluent into a first residual effluent thickener. 7. The method of claim 6, wherein the first residual effluent is contacted with one or more additives (1) simultaneously with the first residual effluent being in the first residual effluent thickener, (2) after the first residual effluent has exited the first residual effluent thickener, or (3) a combination thereof. 8. The method according to claim 7, characterized in that the first residual outlet stream is brought into contact with (1) (a) a flocculant, (b) a coagulant, or (c) a combination thereof, when the first residual effluent stream is in a first residual effluent thickener, (2) (a) a conditioning additive, (b) a surfactant, or (c) a combination thereof (A) simultaneously as the first residual effluent stream is in the first residual effluent thickener, (B) after the first residual effluent stream has exited the first residual effluent thickener, or (C) a combination thereof, (3) the seeding agent (1) when the first residual effluent is in the first residual effluent thickener, (2) after the first residual effluent exits the first residual effluent thickener, or (3) a combination thereof, or (4) their combination. 9. The method according to any one of paragraphs 1-3, characterized in that providing the tailings stream includes: (1) introducing the waste stream into a waste stream thickener; and (2) collecting the tailings stream from the waste stream thickener. 10. The method of claim 9, further comprising, after collecting the tailings stream, diluting the tailings stream with a quantity of liquid sufficient to give the tailings stream a solids content of from 2 to 40% by weight of the tailings stream. 11. The method of claim 9, further comprising introducing the second residual effluent stream into a waste stream thickener. 12. The method according to any one of paragraphs 1-3, characterized in that the first residual effluent comprises the first centrate from a solid rotor centrifuge. 13. The method according to any one of paragraphs 1-3, characterized in that the first cake has from 60 to 99% by weight of the solids content of the tailings stream. 14. The method according to any one of paragraphs 1-3, characterized in that the first cake has from 60 to 90% by weight of the solids content of the tailings stream. 15. The method according to any one of paragraphs 1-3, characterized in that the first cake has a water content of 20 to 45% by weight of the mass of the first cake. 16. The method according to any one of claims 1 to 3, characterized in that the total amount of solids present in the first cake and the second cake is at least 90% by weight of the solids content of the tailings stream. 17. The method according to any one of claims 1 to 3, characterized in that the total amount of solids present in the first cake and the second cake is at least 95% by weight of the solids content of the tailings stream. 18. The method according to any one of claims 1 to 3, characterized in that the total amount of solids present in the first cake and the second cake is at least 99% by weight of the solids content of the tailings stream. 19. The method according to any one of paragraphs 1-3, characterized in that the first residual effluent is brought into contact with a flocculant in an amount of from 1 to 150 g of flocculant per ton of dry matter content in the tailings stream. 20. The method according to any one of paragraphs 1-3, characterized in that the first residual effluent is brought into contact with a flocculant in an amount of from 1 to 50 g of flocculant per ton of dry matter content in the tailings stream. 21. The method according to any one of paragraphs 1-3, characterized in that the flocculant contains a non-ionic flocculant. 22. The method according to any one of paragraphs 1-3, characterized in that the flocculant contains an anionogenic flocculant or a cationogenic flocculant. 23. The method according to any one of paragraphs 1-3, characterized in that the flocculant is in the form of a powder before contacting the first residual effluent with the flocculant and the method further comprises: (A) optionally adjusting the pH of the aqueous liquid and introducing the powder into the aqueous liquid prior to contacting the first residual effluent stream with one or more additives; or (B) Providing an aqueous liquid into which the powder has been introduced. 24. The method according to any one of paragraphs 1-3, characterized in that the flocculant is a high molecular weight polymer flocculant or a very high molecular weight polymer flocculant. 25. The method according to any of paragraphs 1-3, characterized in that (1) the flocculant is selected from the group consisting of NALCO™ 749222 flocculant, YONGXING™ YX1224-6 flocculant, YONGXING™ PAM flocculant, YIXING™ ARAM01 flocculant, ULTRACLEAR™ ProFlocculant™ flocculant, GLORY™ flocculant, ZETAG™ 8127 flocculant (BASF, USA), ZETAG™ 4145 flocculant (BASF, USA), MAGNAFLOC® LT20 flocculant (BASF, USA), MAGNAFLOC® 338 flocculant (BASF, USA), MAGNAFLOC® 10 flocculant (BASF, USA), MAGNAFLOC® 155 (BASF, USA), flocculant MAGNAFLOC® 10 (BASF, USA), flocculant MAGNAFLOC® 155 (BASF, USA), flocculant MAGNAFLOC® 1011 (BASF, USA), flocculant MAGNAFLOC® 5250 (BASF, USA), flocculant MAGNAFLOC® 336 (BASF, USA), flocculant MAGNAFLOC® 919 (BASF, USA), flocculant RHEOMAX® 1050 (BASF, USA), flocculant RHEOMAX® ETD 9010 (BASF, USA), polyacrylamide flocculant MAGNAFLOC® LT27AG (BASF, USA), acrylic homopolymer flocculant ZETAG™ 7109 (BASF, USA), flocculant MAGNAFLOC® 333 (BASF, USA), flocculant FLOBEADS® KB206SH (SNF, UK), flocculant FLOBEADS® KB156 (SNF, UK), flocculant FLOPAM® FO4190 (SNF, UK), flocculant FLOPAM® FO4140 (SNF, UK), flocculant FLOQUAT® TS 45 SH (SNF, UK), flocculant FLOPAM® FA920VHM (SNF, UK), flocculant FLOPAM® FA920VHR (SNF, UK), flocculant FLOPAM® FA920SD (SNF, UK), flocculant FLOPAM® FA920SHD (SNF, UK), flocculant FLOPAM® FA920 (SNF, UK), flocculant ALCLAR® 5000 (BASF, USA), flocculant ALCLAR® 600 (BASF, USA), flocculant ALCLAR® 661 (BASF, USA), flocculant ALCLAR® HP20 (BASF, USA), flocculant ALCLAR® HP21 (BASF, USA), flocculant ALCLAR® HP22 (BASF, USA), flocculant DRIMAX® 1235 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1238 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1240 (Allied Colloids Ltd., UK), flocculant LUPROMIN® F-20X (BASF, USA), flocculant LUPROMIN® FP 18 AS (BASF, USA), flocculant LUPROMIN® FP 199 (BASF, USA), flocculant HI-TEX® 82230 (Hi-Tex Corp, USA), or a combination thereof, (2) the coagulant is selected from the group consisting of coagulant MAGNAFLOC® LT7991 (BASF, USA), coagulant MAGNAFLOC® LT32 (BASF, USA), coagulant MAGNAFLOC® LT38 (BASF, USA), coagulant MAGNAFLOC® 1425 (BASF, USA), coagulant FLOQUAT® FL2549SEP (SNF, UK), FLOQUAT® FLB1725SEP (SNF, UK), FLOQUAT® FL5323 (SNK, UK), and a combination thereof, or (3) their combination. 26. The method according to any one of paragraphs 1-3, characterized in that the swelling clay contains illite-smectite, smectite, montmorillonite or a combination thereof. 27. The method according to claim 3, characterized in that the non-swelling clay contains kaolinite, illite, or a combination thereof. 28. The method according to any one of paragraphs 1-3, characterized in that the swelling clay is present in the tailings stream in an amount from 0.5 to 50% by absolute content of the solids content in the tailings stream. 29. The method according to any one of paragraphs 1-3, characterized in that the dewatering device is a centrifuge with a solid rotor. 30. The method according to any one of paragraphs 1-3, characterized in that the tailings stream comprises (1) coal beneficiation plant tailings, (2) ore beneficiation plant tailings, (3) XX settling basin tailings, (4) XX tailings, or (5) a combination thereof. 31. The method according to any one of paragraphs 1-3, characterized in that the solids content in the tailings stream is from 15 to 30 wt.% of the mass of the tailings stream. 32. The method according to any one of paragraphs 1-3, characterized in that the tailings stream has a mineral residue content of 10 to 80% by weight of the mass content of solids in the tailings stream. 33. The method according to any one of paragraphs 1-3, characterized in that the percentage, by weight, of solids in the tailings stream that are not retained by the 60 mesh woven metal mesh is from 50 to 100%. 34. The method according to any one of paragraphs 1-3, characterized in that the percentage, by weight, of solids in the tailings stream that are not retained by the 400 mesh woven metal mesh is from 25 to 80%. 35. The method according to any one of claims 1 to 3, characterized in that (1) the amount of suspended solids in the second residual effluent stream is from 10 to 750 mg/L or (2) the second residual effluent stream has a turbidity of from 10 to 100 NEF. 36. The method according to claim 1, characterized in that said one or more additives are selected from the group consisting of a flocculant, a coagulant, a surfactant, and a seeding agent. 37. The method according to claim 1, characterized in that said dewatering device includes a belt press filter, a horizontal belt vacuum filter, a rotating vacuum drum filter, a rotating vacuum disc filter, a centrifuge with a mesh rotor, a steep cone paste thickener, a membrane filter press, or an additional centrifuge with a solid rotor. 38. The method according to claim 1, characterized in that said dewatering device includes an additional centrifuge with a solid rotor. 39. The method according to claim 1, characterized in that said swelling clay is present in the tailings stream in an amount of at least 10% by absolute content of the solids content in the tailings stream. 40. The method according to claim 1, characterized in that said swelling clay is present in the tailings stream in an amount of at least 25% by absolute content of the solids content in the tailings stream. 41. A method for treating a waste stream, comprising: providing a tailings stream, wherein the tailings stream has a solids content that (1) is present in an amount of 10 to 40 wt.% of the tailings stream mass, (2) consists of a population of particles, wherein at least 25% by weight of the population of particles is not retained by a 400 mesh woven metal mesh, and wherein at least 10% by volume of the population of particles has an average largest dimension of 2 microns or less; contacting the tailings stream with one or more additives, wherein the one or more additives are selected from the group consisting of a flocculant, a coagulant, a conditioning additive, a surfactant, and a seeding agent; and dewatering the tailings stream using a solid rotor centrifuge to produce a first cake and a first residual effluent. 42. The method according to claim 41, characterized in that the tailings stream contains clay. 43. The method according to claim 42, characterized in that the clay contains swelling clay. 44. The method of claim 43, wherein (1) the swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, (2) the clay further comprises a non-swelling clay, wherein the non-swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, or (3) a combination thereof. 45. The method according to any one of paragraphs 41-44, characterized in that the tailings stream is brought into contact with a flocculant in an amount of from 250 to 500 g per ton of dry matter content in the tailings stream. 46. The method according to any of paragraphs 41-44, characterized in that (1) the flocculant is selected from the group consisting of NALCO™ 749222 flocculant, YONGXING™ YX1224-6 flocculant, YONGXING™ PAM flocculant, YIXING™ ARAM01 flocculant, ULTRACLEAR™ ProFlocculant™ flocculant, GLORY™ flocculant, ZETAG™ 8127 flocculant (BASF, USA), ZETAG™ 4145 flocculant (BASF, USA), MAGNAFLOC® LT20 flocculant (BASF, USA), MAGNAFLOC® 338 flocculant (BASF, USA), MAGNAFLOC® 10 flocculant (BASF, USA), MAGNAFLOC® 155 (BASF, USA), flocculant RHEOMAX® 1050 (BASF, USA), flocculant RHEOMAX® ETD 9010 (BASF, USA), polyacrylamide flocculant MAGNAFLOC® LT27AG (BASF, USA), acrylic homopolymer flocculant ZETAG™ 7109 (BASF, USA), flocculant MAGNAFLOC® 333 (BASF, USA), flocculant FLOBEADS® KB206SH (SNF, UK), flocculant FLOBEADS® KB156 (SNF, UK), flocculant FLOPAM® FO4190 (SNF, UK), flocculant FLOPAM® FO4140 (SNF, UK), flocculant FLOQUAT® TS 45 SH (SNF, UK), flocculant FLOPAM® FA920VHM (SNF, UK), flocculant FLOPAM® FA920VHR (SNF, UK), flocculant FLOPAM® FA920SD (SNF, UK), flocculant FLOPAM® FA920SHD (SNF, UK), flocculant FLOPAM® FA920 (SNF, UK), flocculant ALCLAR® 5000 (BASF, USA), flocculant ALCLAR® 600 (BASF, USA), flocculant ALCLAR® 661 (BASF, USA), flocculant ALCLAR® HP20 (BASF, USA), flocculant ALCLAR® HP21 (BASF, USA), flocculant ALCLAR® HP22 (BASF, USA), flocculant DRIMAX® 1235 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1238 (Allied Colloids Ltd., UK), flocculant DRIMAX® 1240 (Allied Colloids Ltd., UK), flocculant LUPROMIN® F-20X (BASF, USA), flocculant LUPROMIN® FP 18 AS (BASF, USA), flocculant LUPROMIN® FP 199 (BASF, USA), HI-TEX® 82230 (Hi-Tex Corp, USA), or a combination thereof, (2) the coagulant is selected from the group consisting of coagulant MAGNAFLOC® LT7991 (BASF, USA), coagulant MAGNAFLOC® LT32 (BASF, USA), coagulant MAGNAFLOC® LT38 (BASF, USA), coagulant MAGNAFLOC® 1425 (BASF, USA), coagulant FLOQUAT® FL2549SEP (SNF, UK), FLOQUAT® FLB1725SEP (SNF, UK), FLOQUAT® FL5323 (SNK, UK), and a combination thereof, or (3) their combination. 47. The method according to any one of paragraphs 41-44, characterized in that the total amount of solids present in the first cake is from 65 to 99 wt.% of the solids content in the tailings stream. 48. The method according to any one of paragraphs 41-44, characterized in that the first cake has a water content of 15 to 40% by weight of the mass of the first cake. 49. The method according to any one of paragraphs 41-44, characterized in that the first cake has a water content of 30 to 40% by weight of the mass of the first cake. 50. The method according to any one of paragraphs 41-44, characterized in that the solids content in the tailings stream is from 10 to 25% by weight of the mass of the tailings stream. 51. The method of any one of paragraphs 41-44, characterized in that (1) at least 30% by weight of the population of particles are not retained by a 400 mesh woven metal mesh, and (2) at least 20% by volume of the population of particles have an average largest dimension of 2 microns or less, or (3) a combination thereof. 52. The method of any one of paragraphs 41-44, characterized in that (1) the amount of suspended solids in the second residual effluent stream is from 10 to 750 mg/L or (2) the second residual effluent stream has a turbidity of from 10 to 100 NEF. 53. A flow processing system comprising: a dewatering device for dewatering a tailings stream to produce a first cake and a first residual effluent stream, wherein the tailings stream (1) has a solids content of 2 to 40 wt.% of the tailings stream and (2) comprises clay, wherein the clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, wherein said clay comprises swelling clay, wherein the first residual effluent stream has a solids content of from 0.2 to 15 wt.% of the weight of the first residual effluent stream; and a solid rotor centrifuge designed to dewater the first residual effluent to produce a second cake and a second residual effluent, wherein said dewatering device includes a belt press filter, a horizontal belt vacuum filter, a rotary vacuum drum filter, a rotary vacuum disc filter, a mesh rotor centrifuge, a thickening device, a membrane filter press, a solid rotor centrifuge, or an additional solid rotor centrifuge. 54. The system of claim 53, wherein (1) the swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, (2) the clay further comprises a non-swelling clay, wherein the non-swelling clay is present in the tailings stream in an amount of at least 0.5% by absolute content of the solids content of the tailings stream, or (3) a combination thereof. 55. The system according to any one of paragraphs 53, 54, further comprising a waste stream thickener designed to produce an undersize product containing a tailings stream. 56. The system of claim 55, further comprising a liquid feedstock configured to dilute the tailings stream with liquid prior to dewatering the tailings stream. 57. The system of any one of claims 53, 54, further comprising a first residual effluent thickener located between the dewatering device and the solid rotor centrifuge, wherein the first residual effluent thickener is configured to increase the solids content of the first residual effluent by from 1 to 40 mass percentage points. 58. The system of claim 57, further comprising one or more additive feedstocks, wherein each of the one or more additive feedstocks is independently configured to contact the first residual effluent stream with one or more additives (1) before the first residual effluent stream is introduced into the first residual effluent thickener, (2) while the first residual effluent stream is introduced into the first residual effluent thickener, or (3) after the first residual effluent stream exits the first residual effluent thickener. 59. The system according to any one of paragraphs 53, 54, characterized in that the system additionally comprises a conveyor designed to collect the first cake, the second cake, or both the first cake and the second cake. 60. The system according to any one of paragraphs 53, 54, characterized in that it additionally contains one or more additive feedstocks designed to contact the tailings stream with one or more additives; In this case, the said dewatering device is an additional centrifuge with a solid rotor. 61. The system of claim 53, wherein said dewatering device comprises a belt press filter, a horizontal belt vacuum filter, a rotary vacuum drum filter, a rotary vacuum disc filter, a mesh rotor centrifuge, a steep cone paste thickener, a membrane filter press, or an additional solid rotor centrifuge. 62. The system according to paragraph 53, characterized in that said dewatering device includes an additional centrifuge with a solid rotor.