HK1263389A1

HK1263389A1 - Installation for the preparation of an aqueous solution comprising at least one earth alkali hydrogen carbonate

Info

Publication number: HK1263389A1
Application number: HK19121173.9A
Authority: HK
Inventors: N·C·内尔森; H·雷普; W·克罗伊格
Original assignee: Omya国际股份公司
Priority date: 2016-02-05
Filing date: 2017-02-03
Publication date: 2020-06-05

Description

Device for producing an aqueous solution containing at least one earth alkali hydrogen carbonate

Technical Field

The invention relates to a device for producing an aqueous solution containing at least one earth alkali hydrogen carbonate, to the use of said device for producing an aqueous solution containing at least one earth alkali hydrogen carbonate, and to the use of said device for mineralizing and/or stabilizing water.

Background

Drinking water has become scarce. Even in water-rich countries, not all water sources and reservoirs are suitable for producing drinking water, and many water sources today are threatened by a drastic deterioration of the water quality. The feed water originally used for drinking purposes was primarily surface water and ground water. However, for environmental and economic reasons, the treatment of seawater, brine, brackish water, wastewater and contaminated discharge water is becoming increasingly important.

In order to recover water (for drinking) from sea water or brackish water, several apparatuses and methods are known which are of considerable importance for arid areas, coastal areas and islands in the sea, and these generally include distillation, electrolysis and osmotic or reverse osmosis methods. The water obtained from these processes is very soft and has a low pH due to the lack of pH buffering salts, and therefore the water obtained from these processes tends to be highly reactive and unless treated, can create severe corrosion difficulties during its distribution in conventional pipelines. Furthermore, untreated desalinated water cannot be used directly as a source of drinking water. To prevent the dissolution of undesirable substances in pipeline systems, to avoid corrosion of water supply equipment such as pipes and valves and to make water palatable, it is necessary to increase the mineral and alkalinity content of the water.

The traditional method and corresponding equipment mainly used for water mineralization is lime addition by carbon dioxide and limestone bed filtration (also called calcite contactor) and dissolution with partial carbonation. Other less common methods of mineralization include, for example, the addition of slaked lime and sodium carbonate, the addition of calcium sulfate and sodium bicarbonate, or the addition of calcium chloride and sodium bicarbonate.

The lime process involves the use of CO₂Acidifying water to treat lime solutions, wherein the following reactions are involved:

from the above reaction scheme, it can be concluded that two equivalents of CO are required₂One equivalent of Ca (OH)₂Conversion to Ca²⁺And bicarbonate for mineralization. The process depends on two equivalents of CO₂To convert alkaline hydroxide ions into the buffer species HCO₃ ^-. For the mineralization of water, a saturated calcium hydroxide solution, commonly referred to as lime water, is prepared from lime milk (usually up to 5% by weight), based on the total weight, in an amount of 0.1-0.2% by weight. It is therefore necessary to use a saturator that produces lime water and a large volume of lime water is required to achieve the target levels of minerals and alkalinity content. Another drawback of this method is that the slaked lime is corrosive and requires appropriate handling and special equipment. Furthermore, an improperly controlled addition of hydrated lime to soft water may result in an undesirable pH change due to the fact that lime does not have buffering properties.

The limestone bed filtration process includes the step of passing soft water through a bed of granular limestone to dissolve calcium carbonate in the water stream. Limestone and CO are reacted according to₂Contact of acidified water to mineralize water:

unlike the lime process, only one equivalent of CO is stoichiometrically required₂Namely, one equivalent of CaCO₃Conversion to Ca²⁺And bicarbonate for mineralization and alkalinity addition. Furthermore, limestone is non-corrosive and is due to CaCO₃Prevents large pH variations. However, as the pH increases, the reaction slows, making it necessary to add additional CO₂Metering to ensure sufficient CaCO₃Is dissolved. Unreacted CO₂And then removed by stripping or neutralization with sodium hydroxide.

Methods and systems for water mineralization using lime milk or lime slurry are described in US7,374,694 and EP 0520826. US 5,914,046 describes a method for reducing the acidity of wastewater discharge using a pulsed limestone bed.

US7,771,599 describes a method of mineralising process water in a desalination system. The process separates carbon dioxide gas from seawater or the concentrate (brine) of a desalination process via a gas transfer membrane. The separated carbon dioxide gas is then used to produce soluble calcium bicarbonate (Ca (HCO)₃)₂). WO 2012/020056 a1 is directed to a method of mineralising water comprising the steps of providing feed water and injecting gaseous carbon dioxide and a slurry into the feed water, wherein the slurry comprises micronized calcium carbonate. WO 2010/023742 a2 describes a method and an apparatus for producing drinking water by post-processing (post-treatment) desalinated water obtained by desalinating seawater via distillation or reverse osmosis. The method includes a carbon dioxide absorption process of excessively supplying carbon dioxide to desalted water to absorb the carbon dioxide, a mineralization process of passing desalted water adsorbed by the carbon dioxide through a limestone filter in which limestone is filled to form calcium ions and bicarbonate ions, and a carbon dioxide discharge process of supplying air to desalted water passed through the mineralization process to discharge the carbon dioxide and the air to obtain drinking water. WO 2012/113957 a1 relates to a method for remineralizing a fluid, wherein the final turbidity is controlled. The method comprises the steps of reagent dosing, remineralization and filtration. EP 2565165 a1 relates to a water mineralization method comprising the steps of: providing a feed water, providing an aqueous calcium carbonate solution, wherein the aqueous calcium carbonate solution comprises dissolved calcium carbonate and reactive species thereof, and combining the feed water and the aqueous calcium carbonate solution. EP 2623466A1 relates to a process for preparing a polycarbonate comprising at least one earth alkali hydrogen carbonateA method for producing an aqueous solution and the use thereof. The process may be carried out in a reactor system comprising a tank equipped with an agitator, at least one filtration device, and a milling device. EP 2623467 a1 relates to a process for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate and the use thereof. The process is carried out in a reactor system comprising a tank equipped with an agitator and at least one filtration device. EP 2623564 a1 relates to an apparatus for purifying minerals, pigments and/or fillers and/or for producing precipitated alkaline earth metal carbonates and/or water mineralization and the use of such an apparatus for purifying minerals, pigments and/or fillers and/or for water mineralization and/or for producing precipitated alkaline earth metal carbonates. WO 2013/132399a1 relates to water mineralization by: mixing carbonate in powder form into water in a rapid process, generating CO in water₂But increases its turbidity. The treated water is then transported through a reactor with granular carbonates, wherein the CO in the water₂The additional carbonate is dissolved in a slow manner. The reactor simultaneously adds additional minerals and alkalinity to the water and removes the turbidity of the water by dissolving the residual powder and filtering insoluble particles. CN102826689 a1 relates to a post-treatment process of desalted seawater, comprising the following steps: (1) introducing CO₂Adding into desalted seawater and mixing thoroughly; and (2) adding CO₂The desalted seawater is mineralized in a mineralization pool; arranging a calcium carbonate filter bed in the mineralization pond; and adding CO₂The desalinated seawater of (a) is passed through a calcium carbonate filter bed to effect substantial contact and reaction with the calcium carbonate. WO2013/014026 a1 relates to a method for treating water and the use of calcium carbonate in such a method. In particular, it relates to a process for remineralisation of water comprising the steps of: (a) providing a feed water having a carbon dioxide concentration of at least 20mg/l, preferably in the range of 25 to 100mg/l, and more preferably in the range of 30 to 60mg/l, (b) providing an aqueous slurry comprising micronized calcium carbonate, and (c) combining the feed water of step (a) with the aqueous slurry of step (b) to obtain remineralized water. WO 2014/187666A1 relates to a multi-batch system for preparing calcium bicarbonate solutionsAnd the use of such a two-batch system for the preparation of a solution of calcium bicarbonate. WO 2014/187613a1 relates to a device for preparing a solution of calcium bicarbonate and to the use of such a device for the continuous preparation of a solution of calcium bicarbonate and to the use of such a device for the remineralization of water.

US 2009/0101573 a1 relates to a wastewater treatment plant and method, a mineral mixing tank receiving biologically treated water, sludge produced by biological treatment and mineral sludge containing calcium etc. from a settling tank. The mineral pump returns the sludge and treated water from the mineral mixing tank to the raw water tank. An air lift pump circulates the treated water between a re-aeration tank having a semi-anaerobic section and a denitrification tank. The semi-anaerobic stage mitigates environmental changes of the microorganisms during circulation of the treated water between the re-aeration tank and the denitrification tank, and thereby achieves an environment required to promote the propagation of the microorganisms. The air lift pump enables stirring with low energy consumption even when the microorganisms are cultured to their high concentration. WO 2006/128730 a1 describes a process for treating a feed stream of an aqueous medium of a given composition, the feed stream comprising components which may form scale dissolved in a Reverse Osmosis (RO) system under given process conditions, thereby providing a permeate stream and a retentate (concentrate) stream comprising components which may form scale in concentrations high enough to cause scale formation in those parts of the RO system which are in contact with said retentate in the absence of a scale inhibitor, in which process (a) the retentate is continuously monitored for the presence of particles of components which may form scale in said retentate and readings of one or more physical parameters of the retentate relating to the presence of these particles are continuously recorded; (b) continuously comparing the recorded readings with measured values of said one or more parameters of a retentate obtained from an aqueous medium of the same composition under the same process conditions, the values of said process conditions being empirically predetermined; and (c) once the recorded readings of said one or more parameters differ from said predetermined measurements, adding an amount of scale inhibitor to the RO system upstream of the membrane, said amount of scale inhibitor having been empirically predetermined to prevent scale formation under said conditions. WO 98/46533 a1 relates to a system for purifying water to remove at least one of natural organic matter, colour, turbidity, bacteria, cysts and oocysts, viruses, arsenic compounds and insoluble impurities. The system comprises the following steps: providing a water body to be purified; controlling the pH value of the water body to be in the range of 5 to 8; and adding a coagulant to the body of water to provide floes. The floe is maintained in the water body at a concentration of 1-6 for the purpose of adsorbing at least one of natural organic matter, color, turbidity, and bacteria to provide treated water. Thereafter, a first portion of the treated water and floes is removed from the body of water. US 6,027,649 a relates to a system for purifying water to remove at least one of natural organic matter, color, turbidity, bacteria, cysts and oocysts, viruses, arsenic compounds and insoluble impurities. The system comprises the following steps: providing a water body to be purified; controlling the pH value of the water body within the range of 5-8; and adding a coagulant to the body of water to provide floes. The floe is maintained in the water body at a concentration of 1-6 for the purpose of adsorbing at least one of natural organic matter, color, turbidity, and bacteria to provide treated water. Thereafter, a first portion of the treated water and floes is removed from the body of water. A submerged semi-permeable membrane is provided in the body of water for removing a second portion of the treated water. The membrane has a pore size of 0.02-1 μm to provide a permeate consisting of purified water and a retentate comprising floes. The water is treated by mixing to minimize membrane fouling and to allow for thorough mixing of the floes in the water. US 2010/0224541 a1 describes a small bubble diffuser tube capable of producing small bubbles uniformly and consistently, even when the diffuser tube has a long length; a small bubble diffusing device and an immersed membrane separation apparatus using such a tube were manufactured. US2013/0064741 a1 relates to a system for fixing carbon dioxide. The system includes a first reactor for extracting an alkali metal component from the slag and a second reactor for carbonating the extracted alkali metal component with carbon dioxide. With such a system, carbon dioxide can then be fixed in a simpler and cost-effective manner.

However, as described in the prior artThe apparatus has the following disadvantages: mineralization and/or stabilization of water and especially the preparation of aqueous solutions (for mineralization of water) comprising at least one alkaline earth bicarbonate show CO that can still be improved₂Efficiency and/or excessive energy consumption.

In view of the above, it would still be of interest to the skilled person to improve the mineralization and/or stabilization of water. It would be particularly desirable to provide an alternative or improved apparatus for the preparation of an aqueous solution comprising at least one earth alkali hydrogen carbonate which can be prepared in a more efficient, economical and ecological manner, in particular for the apparatus or the process carried out therein, to be able to increase the CO₂The efficiency of the consumption and without excessive energy consumption for the device and the corresponding method.

Disclosure of Invention

It is therefore an object of the present invention to provide an apparatus for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate. Another object may be seen to provide an apparatus for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate which increases the CO used in the apparatus or the process carried out therein₂The consumption efficiency. Another object may be seen to provide an apparatus for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate which is capable of reducing the total energy consumption for the apparatus and the corresponding process. Another object may be seen to be to provide an apparatus for the preparation of an aqueous solution comprising at least one earth alkali bicarbonate, wherein the production of sludge is reduced compared to the typical lime systems of the prior art.

One or more of the foregoing and other problems are solved by the subject matter defined herein in the independent claims. Advantageous embodiments of the invention are defined in the respective dependent claims.

A first aspect of the invention relates to an apparatus for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate. The apparatus comprises

a) A process flow line for providing water,

b) at least one dosing unit adapted for dosing at least one alkaline earth metal carbonate-containing material into at least a portion of the water provided in the process flow line for obtaining an aqueous suspension comprising at least one alkaline earth metal carbonate-containing material,

c) at least one adapted for feeding CO₂Or pK_aValue of<5 into at least a portion of the water provided in the process stream line or into an aqueous suspension comprising at least one alkaline earth metal carbonate-containing material, for obtaining an aqueous suspension S1 comprising at least one alkaline earth metal bicarbonate, and

d) a vessel (container) connected to the at least one process stream line via an inlet, wherein the vessel is

i) Is configured such that at least one submerged membrane module is located in the container for filtering at least a part of the aqueous suspension S1 by passing the aqueous suspension S1 through the at least one submerged membrane module to obtain an aqueous solution S2 comprising at least one earth alkali bicarbonate, and

ii) comprises at least one outlet for releasing an aqueous solution S2 comprising at least one earth alkali hydrogen carbonate from the vessel.

According to another aspect of the present invention, there is provided the use of an apparatus as defined herein for the preparation of an aqueous solution comprising at least one earth alkali hydrogen carbonate.

According to a further aspect of the present invention there is provided the use of an apparatus as defined herein for the mineralization and/or stabilization of water.

According to an embodiment of the apparatus according to the invention, the at least one dosing unit is i) connected to a storage vessel for solid material, and/or ii) configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the process stream line, or iii) connected to a holding means (vessel) suitable for preparing an aqueous suspension comprising the at least one alkaline earth metal carbonate-containing material, wherein the holding means is connected to the process stream line through an inlet for introducing water provided in the process stream line and an outlet for releasing the aqueous suspension comprising the at least one alkaline earth metal carbonate-containing material, or iv) connected to the vessel.

According to another embodiment of the apparatus according to the invention, the vessel is a reactor tank, preferably a sealed reactor tank.

According to a further embodiment of the apparatus according to the invention, the container comprises recirculation means configured to cause air or process fluid to be recirculated through at least a portion of the surface of the at least one submerged membrane module from the bottom to the top direction of the at least one submerged membrane module and/or the container.

According to one embodiment of the device, the at least one apparatus c) i) is configured such that the CO is₂Or pK_aValue of<5 is dosed directly into the water provided in the process stream line, or ii) is connected to a receiving vessel suitable for preparing an aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate, wherein the receiving vessel is connected to the process stream line via an inlet for introducing the water provided in the process stream line and an outlet for releasing the aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate, or iii) is connected to the container, preferably to the recirculation means, which is suitable for recirculating air or process fluid through at least a part of the surface of the at least one submerged membrane module from the bottom to the top direction of the at least one submerged membrane module and/or container.

According to another embodiment of the invention, wherein the at least one submerged membrane module a) has<1 μm, and more preferably<0.1 μm, e.g. 0.04-0.9 μm, such as about 0.04 μm or 0.08 μm, and/or b) has a pore size of ≥ 10 l/(m)²h) Preferably 50 to 150 l/(m)²h) And most preferably 80 to 150 l/(m)²h) And/or c) is made of ceramic, polymer or other synthetic material.

According to yet another embodiment of the apparatus according to the present invention, the at least one process stream line comprises one or more main process stream lines.

According to an embodiment of the apparatus according to the invention, the at least one process stream line comprises two main process stream lines, preferably a main branch of the main process stream line and a side branch of the main process stream line.

According to another embodiment of the apparatus according to the invention, the at least one dosing unit is located in a side branch of the main process stream line.

According to a further embodiment of the apparatus according to the invention, the main branch of the main process flow line and the side branch of the main process flow line are configured such that they merge together upstream of the vessel.

According to one embodiment of the apparatus according to the present invention, the at least one process stream line comprises a main process stream line and one or more side process stream lines, preferably a main process stream line and one or two side process stream lines.

According to another embodiment of the apparatus according to the invention the at least one process stream line comprises one main process stream line and two side process stream lines, preferably a main branch of the side process stream line and a side branch of the side process stream line.

According to a further embodiment of the apparatus according to the invention, the at least one dosing unit is located in the side process stream line or, if present, in the side branch of the side process stream line.

According to an embodiment of the apparatus according to the invention, the main branch of the side process flow line and the side branch of the side process flow line are configured such that they merge together upstream of the vessel.

According to another embodiment of the apparatus according to the invention, the main process stream line and the side process stream line are configured such that they merge together downstream of the vessel.

According to a further embodiment of the apparatus according to the invention, the apparatus comprises a base dosing device downstream of the vessel for introducing a base into the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate.

According to one embodiment of the apparatus according to the invention, the apparatus comprises a base dosing device for introducing a base into the main process stream line downstream of the location where the side process stream line and the main process stream line merge together, preferably for introducing a base into a mixture of an aqueous solution S2 comprising at least one earth alkali hydrogen carbonate together with water in the main process stream line.

It is to be understood that for purposes of the present invention, the following terms have the following meanings.

The term "alkaline earth metal carbonate-containing material" may refer to a material comprising at least 50.0% by weight of alkaline earth metal carbonate, based on the total dry weight of the alkaline earth metal carbonate-containing material.

By "calcium carbonate-containing material" in the meaning of the present invention is meant a material as a source of calcium carbonate, preferably selected from the group consisting of ground calcium carbonate, precipitated calcium carbonate, surface-reacted calcium carbonate, dolomite and mixtures thereof.

The term "mineralization" as used herein means the addition of essential mineral ions and alkalinity to water that is completely free or contains insufficient mineral or alkalinity to obtain palatable water. Mineralization can be achieved by adding at least a specific alkaline earth carbonate, such as calcium carbonate, as the only raw material to the water to be treated. Optionally, for example, to obtain health-related benefits to ensure proper uptake of some essential minerals and trace elements, additional substances such as magnesium salts may be mixed into or with alkaline earth metal carbonates such as calcium carbonate and subsequently added to the water during the mineralization process. The mineralized product may comprise additional minerals selected from magnesium sulfate, potassium or sodium, potassium bicarbonate, sodium bicarbonate or other minerals containing essential trace elements and mixtures thereof, according to national guidelines for human health and drinking water quality. Preferably, the mineralized product comprises additional minerals selected from the group consisting of magnesium sulfate, potassium bicarbonate, sodium bicarbonate, and mixtures thereof.

The term "stabilization" as used in the present invention refers to increasing mineral content and alkalinity to neutralize or remove remaining "aggressive" carbon dioxide and/or to raise pH to achieve a stable and balanced final water quality. This stabilization is preferably achieved by: stripping aggressive carbon dioxide, adding a base to the mineralized water obtained by the inventive apparatus, or a combination of both.

The expression "CO" in the meaning of the present invention₂Efficiency "means the CO in the process carried out in the plant₂Additional CO (initially in the feed water provided in the process stream line and provided by means of at least one unit c)₂(measured in mmol/l)) to the amount (measured in mmol/l) of alkaline earth carbonate (provided by the at least one dosing device) that is converted into alkaline earth bicarbonate with an increase in alkaline earth carbonate (to the aqueous solution S2 produced in the vessel of the inventive apparatus) from the feed water provided in the process stream line.

The expression "acidified" or "acid" in the meaning of the present invention relates to bronsted-lowryTheory, and thus relates to H₃O⁺An ion donor. In addition, the pH of the acid may be>7, for example in>7 to 7.5, provided that there is a suitable corresponding base to receive the H supplied by the acid₃O⁺Ions.

For the purposes of the present invention, "pK_aThe value "indicates the acid dissociation constant associated with a given ionizable hydrogen in a given acid, and indicates that this hydrogen is present inThe natural degree of dissociation from such acids at equilibrium in water at a given temperature. Such a pK_aValues can be found in reference texts such as: harris, d.c. "Quantitative Chemical Analysis: 3 rd edition, 1991, w.h&Co.(USA)，ISBN 0-7167-2170-8。pK_aThe values can be determined according to prior art methods well known to those skilled in the art. pK of acid_aThe values depend on the temperature, unless explicitly stated otherwise, the pK according to the invention_aThe values relate to a temperature of 25 ℃.

The term "downstream" in the meaning of the present invention refers to a later position after another unit of the apparatus.

The term "upstream" in the meaning of the present invention refers to a preceding position before another unit of the apparatus.

When the term "comprising" is used in the present description and claims, it does not exclude other elements. For the purposes of the present invention, the term "consisting of … … (of) is to be considered as a preferred embodiment of the term" comprising or comprising ". If in the following it is defined that a group set (group) comprises at least a certain number of embodiments, this is also to be understood as disclosing a group set, which preferably only consists of these embodiments.

Where an indefinite or definite article is used when referring to a singular noun e.g. "a", "an" or "the", this includes a plural of that noun unless something else is specifically stated.

Terms such as "available" or "definable" and "obtained" or "defined" are used interchangeably. This for example means that unless the context clearly dictates otherwise, the term "obtained" is not meant to indicate that for example an embodiment must be obtained by, for example, a sequence of steps following the term "obtained", although the term "obtained" or "defined" always includes such a restrictive understanding as a preferred embodiment.

The inventors of the present invention have surprisingly found that such an apparatus enables the person skilled in the art to prepare an aqueous solution comprising at least one earth alkali hydrogen carbonate. The inventors of the present invention have also surprisingly found that such an apparatus improves the CO for use in the apparatus or the process carried out therein₂The consumption efficiency. Furthermore, such an apparatus can reduce the total energy consumption for the apparatus and the corresponding method. In addition to this, such a plant enables a reduction in the production of sludge, in particular compared to the typical lime systems of the prior art.

Details and preferred embodiments of the apparatus according to the invention for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate will be described in more detail hereinafter. It is to be understood that these technical details and embodiments also apply, where applicable, to the use of the present invention.

Accordingly, the present invention provides an apparatus for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate, the apparatus comprising

a) A process flow line for providing water,

c) at least one adapted for feeding CO₂Or pK_aValue of<5 into at least a portion of the water provided in the process stream line or an aqueous suspension comprising at least one alkaline earth metal carbonate-containing material, for obtaining an aqueous suspension S1 comprising at least one alkaline earth metal bicarbonate, and

d) a vessel connected to the at least one process stream line via an inlet, wherein the vessel

The apparatus of the present invention is applicable to any process for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate. For example, the device is suitable for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate suitable for the mineralization and/or stabilization of water.

The term "aqueous" solution refers to a system wherein the aqueous solvent comprises or preferably consists of water. However, the term does not exclude that the aqueous solvent comprises a minor amount of at least one water miscible organic solvent selected from the group consisting of methanol, ethanol, acetone, acetonitrile, tetrahydrofuran and mixtures thereof. Preferably, the aqueous solvent comprises at least 80.0% by weight, preferably at least 90.0% by weight, more preferably at least 95.0% by weight, still more preferably at least 99.0% by weight of water, based on the total weight of the aqueous solvent. For example, the aqueous solvent consists of water.

The term aqueous "solution" in the meaning of the present invention refers to a system comprising an aqueous solvent and particles of alkaline earth carbonate and/or alkaline earth bicarbonate, wherein the particles of alkaline earth carbonate and/or alkaline earth bicarbonate are dissolved in the aqueous solvent. The term "dissolved" in the meaning of the present invention refers to a system wherein no discrete solid particles are observed in the aqueous solvent.

The term "at least one" alkaline earth hydrogen carbonate in the meaning of the present invention means that the alkaline earth hydrogen carbonate comprises, preferably consists of, one or more alkaline earth hydrogen carbonates.

In one embodiment of the present invention, the at least one earth alkali hydrogen carbonate comprises, preferably consists of, one earth alkali hydrogen carbonate. Further optionally, the at least one earth alkali hydrogen carbonate comprises, preferably consists of, two or more earth alkali hydrogen carbonates. For example, the at least one earth alkali hydrogen carbonate comprises, preferably consists of, two earth alkali hydrogen carbonates.

Preferably, the at least one earth alkali hydrogen carbonate comprises, more preferably consists of, one earth alkali hydrogen carbonate.

In one embodiment of the invention, the at least one earth alkali hydrogen carbonate is selected from the group consisting of calcium hydrogen carbonate, magnesium hydrogen carbonate and mixtures thereof. Preferably, the at least one earth alkali hydrogen carbonate comprises, preferably consists of, calcium hydrogen carbonate.

a) The method comprises the following steps Process flow line for providing water

According to a) of the apparatus of the invention, the apparatus comprises a process stream line for providing water.

It is understood that the process flow line is preferably formed by pipes, tubes and other such articles suitable for coupling the other units of the apparatus (e.g. the at least one dosing unit, the at least one device c) and the vessel) to each other such that a fluid communication between the units, i.e. a flow of fluid, such as a suspension, from one unit of the apparatus of the invention to another, is achieved. The process stream lines may be any type of pipe, tubing and other such articles known to those skilled in the art and are typically used in coupling units.

The water provided in the process stream line may come from various sources and may be selected from distilled water, tap water, industrial water, desalinated water such as desalinated seawater, brackish water (brakeish water), treated wastewater, water treated by reverse osmosis or natural soft water such as ground water, surface water or rainfall. It may also contain 10-2000 mg/l NaCl. Preferably, the water provided in the process stream is desalted water, such as permeate or distillate obtained from a desalination process.

In one embodiment of the apparatus of the present invention, the water provided in the process stream is water to be mineralized. That is, the water provided in the process stream is water that is completely free of or contains an insufficient amount of minerals or alkalinity.

The water provided in the process stream line may be pretreated. Pretreatment may be necessary, for example, in the case of water originating from surface water, ground water or rainwater. For example, to meet drinking water guidelines, water needs to be treated to remove contaminants, such as organics or undesirable minerals, through the use of chemical or physical techniques. For example, ozonation may be used as a first pretreatment step, followed by coagulation, flocculation, or sedimentation as a second treatment step. For example, iron (III) salts such as FeClSO₄Or FeCl₃Or aluminium salts such as AlCl₃、Al₂(SO₄)₃Or polyaluminium may be used as a flocculating agent. The flocculated material may be removed from the water, for example, by a sand filter or a multi-layer filter. Other water purification methods that can be used to pretreat water are described in e.g. EP 1975310, EP 1982759, EP 1974807 or EP 1974806.

If seawater or brackish water is provided in the process stream, the seawater or brackish water is first pumped out of the sea by subsurface intake such as wells or open ocean intake, and then subjected to physical pretreatment such as screening, sedimentation or sand removal methods. Depending on the desired water quality, additional processing steps such as coagulation and flocculation may be required to reduce potential fouling on the membrane. The pretreated seawater or brackish water can then be distilled, for example, by using: multi-stage flash evaporation, multi-effect distillation, or membrane filtration such as nanofiltration or reverse osmosis to remove remaining particulates and dissolved materials.

It is noted that the water provided in the process stream line is preferably provided in one main process stream line (17) and in one or more side process stream lines (15).

That is, a portion of the water provided in the process stream line is provided in the main process stream line (17) and the remainder of the water is provided in the one or more side process stream lines (15). Thus, the main process stream line (17) and the one or more side process stream lines (15) are connected to each other, preferably the one or more side process stream lines (15) are connected to the main process stream line (17) (through its inlet and outlet).

The process stream lines preferably include a main process stream line (17) and one or more side process stream lines (15). More preferably, the at least one process stream line comprises a main process stream line (17) and one or two side process stream lines (15). For example, the at least one process stream line includes a main process stream line (17) and a side process stream line (15).

A process stream line is considered to be a side process stream line (15) if the main process stream line (17) and the one or more side process stream lines (15) are combined together after obtaining the aqueous solution S2 in the vessel, preferably the reactor tank (1).

Thus, the main process stream line (17) and the side process stream line (15) are preferably configured such that they merge together downstream of the vessel.

If the process stream line comprises two or more side process stream lines (15), the two or more side process stream lines (15) may comprise a main branch (15a) of the side process stream line and one or more side branches (15b) of the side process stream line. For example, the two side process flow lines (15) comprise a main branch (15a) of the side process flow line and a side branch (15b) of the side process flow line.

It is to be understood that the two or more side process flow lines (15) may be branched into a side branch (15b) of the side process flow line providing water for preparing an aqueous suspension or aqueous suspension S1 comprising at least one alkaline earth metal carbonate-containing material, and a main branch (15a) of the side process flow line providing water for diluting an aqueous suspension or aqueous suspension S1 comprising at least one alkaline earth metal carbonate-containing material prepared in the side branch (15b) of the side process flow line. In other words, the side branch (15b) of the side process stream line provides water for the aqueous suspension of the alkaline earth metal carbonate-containing material or aqueous suspension S1, while the main branch (15a) of the side process stream line provides water directly in the vessel, preferably the reactor tank (1).

Thus, a side branch is considered to be a side branch (15b) of the side process stream line if the main branch (15a) and the one or more side branches of the side process stream line merge together before the aqueous suspension or aqueous suspension S1 comprising the alkaline earth metal carbonate material is directed into the vessel, preferably the reactor tank (1). That is, the aqueous suspension or aqueous suspension S1 comprising the alkaline earth metal carbonate material is prepared in the side branch (15b) of the side process stream line and then conducted into the main branch (15a) of the side process stream line, e.g. for diluting the aqueous suspension or aqueous suspension S1 comprising the alkaline earth metal carbonate material, and then the diluted aqueous suspension or aqueous suspension S1 comprising the alkaline earth metal carbonate material is conducted into the vessel, preferably the reactor tank (1), via the main branch (15a) of the side process stream line.

Thus, the main branch (15a) of the side process stream line and the side branch (15b) of the side process stream line are preferably configured such that they merge together upstream of the vessel.

Further optionally, the water provided in the at least one process stream is provided only in the main process stream (17). That is, the apparatus does not include at least one side process stream line. Thus, in one embodiment, the process stream line comprises one or more main process stream lines (17). Preferably, the process stream line consists of one or more main process stream lines (17).

In one embodiment, the process stream line comprises two or more main process stream lines (17). Preferably, the main process flow line (17) may comprise a main branch (17a) of the main process flow line and one or more side branches (17b) of the main process flow line.

For example, the two main process flow lines (17) comprise a main branch (17a) of the main process flow line and a side branch (17b) of the main process flow line.

It is to be understood that the process stream line (17) may be branched into a side branch (17b) of the main process stream line providing water for preparing the aqueous suspension or aqueous suspension S1 of the alkaline earth metal carbonate-containing material, and a main branch (17a) of the main process stream line providing water for diluting the aqueous suspension or aqueous suspension S1 of the alkaline earth metal carbonate-containing material prepared in the side branch (17b) of the main process stream line. In other words, the side branch (17b) of the main process stream line provides water for the aqueous suspension or aqueous suspension S1 of the alkaline earth metal carbonate-containing material, whereas the main branch (17a) of the main process stream line provides water directly in the vessel, preferably the reactor tank (1).

It should be noted that a side branch is considered to be a side branch (17b) of the main process stream line if the main branch (17a) and the one or more side branches of the main process stream line merge together before the aqueous suspension or aqueous suspension S1 comprising the alkaline earth metal carbonate material is directed into the vessel, preferably the reactor tank (1). That is, the aqueous suspension or aqueous suspension S1 of the alkaline earth metal carbonate-containing material is prepared in the side branch (17b) of the main process stream line and then conducted into the main branch (17a) of the main process stream line, for example for diluting the aqueous suspension or aqueous suspension S1 of the alkaline earth metal carbonate-containing material, and then the diluted aqueous suspension or aqueous suspension S1 of the alkaline earth metal carbonate-containing material is conducted into the vessel, preferably the reactor tank (1), via the main branch (17a) of the main process stream line.

Thus, the main branch (17a) of the main process stream line and the side branch (17b) of the main process stream line are preferably configured such that they merge together upstream of the vessel.

b) The method comprises the following steps Dosing unit for at least one alkaline earth metal carbonate-containing material

According to b) of the apparatus of the present invention, the apparatus comprises at least one dosing unit (25) adapted for dosing at least one alkaline earth metal carbonate-containing material into at least a part of the water provided in the process flow line for obtaining an aqueous suspension comprising the at least one alkaline earth metal carbonate-containing material.

The term "at least one" dosing unit in the meaning of the present invention means that the device comprises one or more dosing units. For example, the apparatus comprises one or two, more preferably one dosing unit.

The at least one dosing unit may be any type of dosing unit known to the person skilled in the art and typically used for dosing alkaline earth metal carbonate-containing material into a water stream or directly into a tank.

The at least one dosing unit is configured for dosing at least one alkaline earth metal carbonate-containing material into at least a portion of the water provided in the process stream line. The at least one alkaline earth metal carbonate-containing material preferably comprises, more preferably consists of: one or two such as one alkaline earth metal carbonate-containing material. For example, the at least one dosing unit is configured for dosing at least one alkaline earth metal carbonate-containing material into at least a portion of the water provided in the process flow line, the alkaline earth metal carbonate-containing material comprising, more preferably consisting of: a calcium carbonate-containing material.

According to one embodiment, the at least one alkaline earth metal carbonate-containing material, preferably calcium carbonate-containing material, is selected from the group consisting of precipitated calcium carbonate, modified calcium carbonate, ground calcium carbonate and mixtures thereof. Preferably, the at least one dosing unit is configured for dosing ground calcium carbonate into at least a portion of the water provided in the process stream line.

"Ground Calcium Carbonate (GCC)" in the meaning of the present invention is calcium carbonate obtained from natural sources, including marble, chalk or limestone, and processed via processes such as grinding, screening and/or by wet and/or dry subdivision, for example by cyclones.

"Precipitated Calcium Carbonate (PCC)" in the meaning of the present invention is a synthetic substance, usually by precipitation after reaction of carbon dioxide with lime in an aqueous environment or by precipitation of calcium and carbonate sources in water or by addition of calcium ions and carbonate ions (e.g. CaCl)₂And Na₂CO₃) Precipitating from the solution. Precipitated calcium carbonate exists in three primary crystalline forms: calcite, aragonite and vaterite, and there are many different polymorphs (crystal habit) for each of these crystal forms. Calcite has a triangular structure with typical crystallographic habit such as scalenohedral (S-PCC), rhombohedral (R-PCC), hexagonal prismatic, axial, colloidal (C-PCC), cubic and prismatic (P-PCC). Aragonite is a orthorhombic structure with a typical crystal habit of paired hexagonal prisms, and a variety of classifications for the forms of elongated prisms, curved leaves, steep pyramids, chisel pointed crystals, furcated trees, and coral or worm shapes.

"modified calcium carbonate" in the meaning of the present invention is a surface-reacted natural calcium carbonate which is obtained by the following process: in this process, natural calcium carbonate is mixed with pK at 25 ℃_aOne or more H of 2.5 or less than 2.5₃O⁺The ion donor reacts with gaseous CO formed in situ and/or from an external supply₂And optionally in the presence of at least one aluminium silicate and/or at least one synthetic silica and/or at least one calcium silicate and/or at least one silicate of a monovalent salt (such as sodium silicate and/or potassium silicate and/or lithium silicate) and/or at least one aluminium hydroxide and/or at least one sodium silicate and/or potassium silicate. Further details regarding the preparation of surface-reacted natural calcium carbonate are disclosed in WO 00/39222, WO 2004/083316 and US 2004/0020410A 1, the contents of which are incorporated herein by reference.

The alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material, is preferably Ground Calcium Carbonate (GCC).

For example, the at least one alkaline earth metal carbonate-containing material (preferably calcium carbonate-containing material) is selected from marble, limestone, chalk, half-burnt lime, dolomitic limestone, calcareous dolomite, half-burnt dolomite, and precipitated alkaline earth metal carbonates such as precipitated calcium carbonate, e.g. having calcite, aragonite and/or vaterite mineral crystal structures, e.g. from addition of Ca (OH)₂The de-hardening of the water. The use of marble, limestone and/or chalk is preferred because they are naturally occurring minerals and the turbidity of the final drinking water quality is ensured by using clear aqueous solutions comprising at least one earth alkali bicarbonate produced by using these naturally occurring minerals. Natural marble deposits contain mostly acid-insoluble silicate impurities. However, when using the product prepared by the process of the present invention, this acid-insoluble material (sometimes a colored silicate) does not affect the final water quality in terms of turbidity.

Thus, the at least one dosing unit is configured for dosing Ground Calcium Carbonate (GCC) selected from marble, limestone, chalk and mixtures thereof into at least a portion of the water provided in the process stream line.

According to one embodiment of the invention, the at least one alkaline earth metal carbonate-containing material comprises, preferably consists of: the particles consist of an alkaline earth carbonate in an amount of ≥ 40.0% by weight, preferably 90.0% by weight, more preferably ≥ 95.0% by weight and most preferably ≥ 97.0% by weight, based on the total dry weight of the at least one alkaline earth carbonate-containing material.

For example, the at least one calcium carbonate-comprising material comprises, preferably consists of: the particles consist of calcium carbonate in an amount of ≥ 40.0% by weight, preferably 90.0% by weight, more preferably ≥ 95.0% by weight and most preferably ≥ 97.0% by weight, based on the total dry weight of the at least one calcium carbonate-containing material.

Further preferably, the at least one dosing unit is configured for dosing micronized alkaline earth metal carbonate-containing material (preferably calcium carbonate-containing material) into at least a portion of the water provided in the process stream line.

For the purposes of the present invention, the term "micronized" means that the particle size is in the micrometer range, for example, from 0.1 to 50.0 μm. Micronized particles may be obtained by techniques based on friction and/or impact (e.g. milling or grinding under wet or dry conditions). However, the micronized particles may also be produced by any other suitable method, such as precipitation, rapid expansion of supercritical solutions, spray drying, classification or differentiation of naturally occurring sands or muds, filtration of water, sol-gel methods, spray reaction synthesis, flame synthesis or liquid foaming synthesis.

For example, the at least one alkaline earth metal carbonate-containing material (preferably calcium carbonate-containing material) has a weight median particle size d of from 0.1 to 50.0 μm, preferably from 0.2 to 25.0 μm, more preferably from 0.3 to 10.0 μm and most preferably from 0.5 to 5.0 μm₅₀。

Throughout this document, the "particle size" of alkaline earth metal carbonate-containing materials and other materials is described by their particle size distribution.

Here, the value d_xThe following diameters are indicated: x% by weight of the particles, relative to the diameter, having a value of less than d_xOf (c) is measured. This means for example d₂₀The value is the particle size below which 20% by weight of all particles are smaller. d₅₀The value is thus the weight median particle size, i.e. 50% by weight of all particles are larger than this particle size and the remaining 50% by weight are smaller than this particle size. For the purposes of the present invention, unless otherwise indicated, the particle size is specified as the weight median particle size d₅₀。d₉₈The values are particle sizes wherein 98% by weight of all particles are smaller than the particle size. By usingParticle size was determined by sedigraph 5100 or 5120 from Micromeritics Instrument Corporation. Methods and apparatus are known to those skilled in the art and are commonly used to determine the particle size of fillers and pigments. At 0.1% by weight Na₄P₂O₇Is measured in an aqueous solution of (a). The samples were dispersed using a high speed stirrer and ultrasound.

In one embodiment of the invention, the alkaline earth metal carbonate-containing material (preferably calcium carbonate-containing material) has a thickness of 0.01 to 200.0m²A/g and preferably from 1.0 to 100.0m²BET specific surface area/g, measured by nitrogen adsorption using the BET isotherm (ISO 9277: 2010).

Additionally or alternatively, the at least one alkaline earth metal carbonate-containing material (preferably calcium carbonate-containing material) may comprise 0.02 to 50.0 wt. -%, 0.03 to 25.0 wt. -%, or 0.05 to 10.0 wt. -% of HCl-insoluble inclusions, based on the total weight of the at least one alkaline earth metal carbonate-containing material (preferably calcium carbonate-containing material). Preferably, the HCl insoluble content of the at least one alkaline earth metal carbonate-containing material does not exceed 1.0 wt%, based on the total weight of the calcium carbonate. The HCl insoluble content may be, for example, minerals such as quartz, silicates, or mica.

In one embodiment, the at least one dosing unit is configured to add the alkaline earth metal carbonate-containing material (preferably calcium carbonate-containing material) in dry form or in aqueous form to at least a portion of the water provided in the process stream line.

If the at least one dosing unit is configured to add the alkaline earth metal carbonate-containing material, preferably the calcium carbonate-containing material, in dry form to at least a part of the water provided in the process stream line, the at least one dosing unit is configured to dose the alkaline earth metal carbonate-containing material, preferably the calcium carbonate-containing material, in powder form or in pellet form to at least a part of the water provided in the process stream line.

The term "dry" in relation to the at least one alkaline earth metal carbonate-containing material, preferably calcium carbonate-containing material, is understood to mean a material having less than 0.3% by weight of water relative to the weight of the at least one alkaline earth metal carbonate-containing material. The water% was determined according to the Coulometric Karl Fischer measurement method, wherein the at least one alkaline earth metal carbonate-containing material was heated to 220 ℃ and the water content released as steam and separated using a nitrogen stream (100ml/min) was determined in a Coulometric Karl Fischer unit.

If the at least one alkaline earth metal carbonate-containing material is dosed in dry form into at least a portion of the water provided in the process stream line using the at least one dosing unit, the dry alkaline earth metal carbonate-containing material may be dosed into a slurry-compression (make-down) system, which is then combined with the water in the process stream line.

If the at least one dosing unit is configured for adding the alkaline earth metal carbonate-containing material, preferably the calcium carbonate-containing material, in aqueous form to at least a part of the water provided in the process stream line, the at least one dosing unit is configured for dosing the alkaline earth metal carbonate-containing material, preferably the calcium carbonate-containing material, in aqueous suspension to at least a part of the water provided in the process stream line. The aqueous suspension preferably has a solids content of from 0.01 to 20.0% by weight, more preferably from 1.0 to 15.0% by weight and most preferably from 2.0 to 10.0% by weight, based on the total weight of the suspension. In such an embodiment, the at least one dosing unit is preferably configured such that the aqueous suspension is produced in situ by: a highly concentrated slurry having a solids content of, for example, 30.0-60.0% by weight, for example, about 40% by weight, or an alkaline earth metal carbonate-containing material (preferably a calcium carbonate-containing material) in, for example, a solid form such as a powder or pellet form, is used without any dispersant.

For the purposes of the present invention, a "suspension" or "slurry" refers to a system comprising a solvent (i.e., an aqueous solvent) and particles comprising an alkaline earth carbonate material and/or an alkaline earth bicarbonate, wherein at least a portion of the particles comprising the alkaline earth carbonate material and/or the alkaline earth bicarbonate are present in the aqueous solvent in the form of insoluble solids. The term does not exclude that a portion of the alkaline earth metal carbonate-containing material and/or alkaline earth metal bicarbonate particles is dissolved in the aqueous solvent.

The suspension comprising the at least one alkaline earth metal carbonate-containing material, preferably calcium carbonate-containing material, may comprise in addition to the at least one alkaline earth metal carbonate-containing material, preferably calcium carbonate-containing material, further micronized mineral. According to one embodiment, the suspension comprising the at least one alkaline earth metal carbonate-containing material (preferably a calcium carbonate-containing material) may comprise micronized calcium magnesium carbonate such as dolomitic limestone, calcareous dolomite or half-burnt dolomite, magnesium oxide such as burnt dolomite, magnesium sulphate, potassium bicarbonate, sodium bicarbonate and/or other minerals containing the necessary trace elements.

For example, the at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material, dosed into at least a portion of the water provided in the process flow line by means of the at least one dosing unit (25) is provided in a storage vessel (13) for solid material. The at least one dosing unit (25) is therefore preferably connected to a storage container (13) for solid material.

The storage vessel (13) may be any type of storage vessel known to the person skilled in the art and typically used for storing alkaline earth metal carbonate-containing material.

Additionally or alternatively, the at least one dosing unit (25) is connected to a receiving vessel (14) adapted for preparing a suspension comprising at least one alkaline earth metal carbonate-containing material. In one embodiment, the at least one dosing unit (25) is preferably connected to a storage vessel (13) for solid material, which storage vessel (13) is connected to a holding vessel (14) suitable for preparing a suspension comprising at least one alkaline earth carbonate material.

The containing means (14) may be any type of containing means known to the person skilled in the art and typically used for preparing a suspension comprising at least one alkaline earth metal carbonate-containing material.

Preferably, the receiving means (14) is connected to the process flow line through an inlet for introducing water provided in the process flow line and an outlet for releasing an aqueous suspension comprising at least one alkaline earth metal carbonate-containing material.

For example, the receiving means (14) is connected to the side process flow line (15), or if the side process flow line comprises a side branch, the receiving means (14) is preferably connected to the side branch (15b) of the side process flow line, such that the water provided in the side process flow line (15) or the side branch (15b) of the side process flow line is used for preparing the suspension comprising the at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material. The suspension (16) comprising the at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material, is then preferably transferred into a vessel, preferably a reactor tank (1). If the side process stream line (15) comprises a side branch, the side branch (15b) of the side process stream line is preferably connected to the main branch (15a) of the side process stream line upstream of the vessel, preferably the reactor tank (1). Thus, for example, the at least one dosing unit connected to the storage vessel (13) and the receiving means (14) is located in the side process stream line (15), or, if the side process stream line comprises a side branch, the at least one dosing unit connected to the storage vessel (13) and the receiving means (14) is located in a side branch (15b) of the side process stream line, for example.

Alternatively, the alkaline earth metal carbonate-containing material may be mixed with the water of the side process stream line (15) in a vessel, preferably a reactor tank (1). That is, the at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material, may be provided in a storage vessel (13), which storage vessel (13) is directly connected to a vessel, preferably to the reactor tank (1).

Thus, the at least one dosing unit may be connected to a vessel (preferably a reactor tank (1)). In one embodiment, the at least one dosing unit (25) is connected to a storage vessel (13), said storage vessel (13) being directly connected to a vessel, preferably a reactor tank (1).

In an alternative embodiment, the at least one alkaline earth metal carbonate-containing material (preferably a calcium carbonate-containing material) is dosed directly into the water provided in the process stream line.

Thus, the at least one dosing unit (25) may be configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the process stream line. In an embodiment, the at least one dosing unit (25) is connected to a storage vessel (13) and the at least one dosing unit is configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the process stream line.

For example, the at least one dosing unit (25) is configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the side process stream line (15), or if the side process stream line comprises a side branch, the at least one dosing unit is configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the side branch (15b) of the side process stream line. It is to be understood that the water provided in the side process flow line (15) or the side branch (15b) of the side process flow line is used for preparing a suspension comprising at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material.

It can thus be understood that the at least one dosing unit (25) is located in the side process stream line. The at least one dosing unit is located in a side branch of the side process flow line if the side process flow line comprises a main branch of the side process flow line and a side branch of the side process flow line.

If the at least one process stream line consists of the main process stream line (17), i.e. does not comprise one or more side process stream lines (15), the at least one dosing unit (25) is preferably connected to a storage vessel (13) for solid material, which storage vessel (13) is connected to a holding vessel (14) suitable for preparing a suspension comprising at least one alkaline earth carbonate-containing material.

Preferably, the receiving means (14) is connected to the main process flow line (17), or if the main process flow line comprises a side branch, the receiving means (14) is preferably connected to a side branch (17b) of the main process flow line, such that water provided in the main process flow line (17) or the side branch (17b) of the main process flow line is used for preparing the aqueous suspension S1 comprising at least one alkaline earth carbonate-containing material, preferably a calcium carbonate-containing material. The suspension (16) comprising the at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material, is then preferably transferred into a vessel, preferably a reactor tank (1). If the main process stream line (17) comprises a side branch, the side branch (17b) of the main process stream line is preferably connected to the main branch (17a) of the main process stream line upstream of the vessel, preferably the reactor tank (1). Thus, for example, the at least one dosing unit connected to the storage vessel (13) and the receiving means (14) is located in the main process stream line (17), or, if the main process stream line comprises a side branch, the at least one dosing unit connected to the storage vessel (13) and the receiving means (14) is located in a side branch (17b) of the main process stream line, for example.

Alternatively, the alkaline earth metal carbonate-containing material may be mixed with the water of the main process stream line (17) in a vessel, preferably a reactor tank (1). That is, the at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material, may be provided in a storage vessel (13), which storage vessel (13) is directly connected to a vessel, preferably to the reactor tank (1).

In a further alternative embodiment, the at least one dosing unit (25) is configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the main process stream line (17), or if the main process stream line comprises a side branch, the at least one dosing unit is configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the side branch (17b) of the main process stream line. It is to be understood that the water provided in the main process stream line (17) or the side branch (15b) of the main process stream line is used for preparing an aqueous suspension S1 comprising at least one alkaline earth metal carbonate-containing material, preferably a calcium carbonate-containing material. In such an embodiment, the main branch (17a) of the main process stream line and the side branch (17b) of the main process stream line are configured such that they merge together upstream of the vessel.

It can thus be understood that if the process stream line consists of the main process stream line (17), the at least one dosing unit (25) is located in the main process stream line. If the main process flow line comprises a main branch (17a) of the main process flow line and a side branch (17b) of the main process flow line, the at least one dosing unit is located in the side branch (17b) of the main process flow line.

The at least one dosing unit is therefore preferably located downstream of the source of water provided in the process stream line. If the process stream line comprises the main process stream line (17) and the side process stream line (15), the at least one dosing unit is preferably located downstream of the side process stream line (15), i.e. after the process stream line is branched to form the main process stream line (17) and the side process stream line (15).

If the main process stream line (17) or the side process stream line (15) comprises branches, the at least one dosing unit (25) is preferably located downstream of a side branch (17b) of the main process stream line or a side branch (15b) of the side process stream line, i.e. after the main process stream line (17) or the side process stream line (15) is branched to form the respective side branch. Additionally or alternatively, the at least one dosing unit (25) is preferably located upstream of the point where the side branch (17b) and the main branch (17a) of the main process stream line or the side branch (15b) and the main branch (15a) of the side process stream line merge together.

Preferably, the at least one dosing unit (25) is located upstream of the vessel, more preferably the reactor tank (1).

₂c) The method comprises the following steps Device for dosing CO or acid

According to c) of the apparatus of the invention, the apparatus comprises at least one apparatus suitable for introducing CO₂Or pK_aValue of<5 into at least a portion of the water provided in the process stream line or into an aqueous suspension comprising at least one alkaline earth metal carbonate-containing material, for obtaining an aqueous suspension S1 comprising at least one alkaline earth metal bicarbonate.

The term "at least one" in the meaning of the present invention applies to the dosing of CO₂Or pK_aValue of<5 means that the apparatus comprises one or more devices suitable for dosing CO₂Or pK_aValue of<5 acid device. For example, the apparatus comprises one or two, more preferably one, adapted for dosing CO₂Or pK_aValue of<5 acid device.

The at least one apparatus c) may be typical for the introduction of CO known to the person skilled in the art₂Or pK_aValue of<5 into water.

The at least one device is configured for converting CO₂Or pK_aValue of<5 into at least a portion of the water provided in the process stream line.

The at least one device is preferably adapted for dosing carbon dioxide selected from gaseous carbon dioxide, liquid carbon dioxide, solid carbon dioxide and gaseous mixtures of carbon dioxide with other gases, such as flue gas comprising carbon dioxide emitted from an industrial process, such as a combustion process or a calcination process or the like. Preferably, the carbon dioxide is gaseous carbon dioxide. When a gaseous mixture of carbon dioxide and other gases is used, then the carbon dioxide is present in a range of from 90.0% to about 99.0% by volume, and preferably from 95.0% to 99.0% by volume, based on the total volume of the gaseous mixture. For example, carbon dioxide is present in an amount of at least 97.0% by volume based on the total volume of the gaseous mixture.

Further optionally, the at least one device is adapted for dosing with a pK at 25 ℃_aValue of<5. Preference is given to<4, or a salt thereof. For example, the at least one device is preferably adapted to dose an acid selected from the group consisting of: sulfuric acid, hydrochloric acid, nitric acid or citric acid and mixtures thereof. In one embodiment, the at least one device is adapted to dose an acid selected from the group consisting of: having a pK at 25 ℃_aAcids having a value less than or equal to 0 and more particularly selected from sulfuric acid, hydrochloric acid or mixtures thereof. Further optionally, the at least one device is adapted to dose the following acids: the acid being a salt having an acidic pH, e.g. an alkali metal salt, e.g. NaHSO₄And/or KHSO₄。

Preferably, the at least one device is adapted for dosing CO₂。

In one embodiment, the CO is added₂Or pK_aValue of<5 into the vessel (1). Thus, the at least one device c) is preferably connected to a vessel (more preferably a reactor tank (1)).

In one embodiment, the vessel, preferably the reactor tank (1), is connected to a recirculation device comprising a recirculation air stream (5). For example, the recirculation device is arranged such that the air flow is recirculated from the bottom to the top direction of the vessel, preferably the reactor tank (1). In one embodiment, the at least one apparatus c) is configured such that the CO is₂Or pK_aValue of<5 is injected into the recirculation air stream (5) of the recirculation device. That is to say, the at least one device c) is configured such that CO₂Or pK_aValue of<5 is injected into the air or process fluid of the recirculation air stream (5) of the recirculation device.

Thus, the vessel, preferably the reactor tank (1), may comprise a recirculation device configured such that air or process fluid is recirculated through at least a portion of the surface of the at least one submerged membrane module from the bottom to the top direction of the at least one submerged membrane module and/or the vessel, preferably the reactor tank (1).

Further optionally, the at least one device may be configured such that the CO₂Or pK_aValue of<5 is dosed directly into the water provided in the process stream.

For example, the at least one device may be configured such that the CO₂Or pK_aValue of<5 is dosed directly into the water provided in the side process stream line (15), or if the side process stream line comprises a side branch, the at least one apparatus may be configured such that the CO₂Or pK_aValue of<5 is dosed directly into the water provided in the main branch (15a) of the side process stream or in the side branch (15b) of the side process stream.

It can thus be appreciated that the at least one device can be located in the side process stream line (15). If the side process stream line (15) comprises a main branch (15a) of the side process stream line and one or more side branches (15b) of the side process stream line, the at least one device is preferably located in one of the side branches (15b) of the side process stream line.

In a further alternative embodiment, the at least one apparatus may be configured such that the CO₂Or pK_aValue of<5 is dosed directly into the water provided in the main process stream line (17), or if the main process stream line comprises a side branch, the at least one apparatus may be configured such that the CO₂Or pK_aValue of<5 is dosed directly into the water provided in the main branch (17a) of the main process stream or in the side branch (17b) of the main process stream.

It can thus be appreciated that if the process flow line consists of the main process flow line (17), the at least one device can be located in the main process flow line. If the main process stream line comprises a main branch (17a) of the main process stream line and one or more side branches (17b) of the main process stream line, the at least one device is preferably located in one of the side branches (17b) of the main process stream line.

In a further alternative embodiment, the at least one device is connected to a containing means (14) suitable for preparing an aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate. Preferably, the containing means (14) are connected to the process flow line through an inlet for introducing water provided in the process flow line and an outlet for releasing an aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate.

In one embodiment, the containing means (14) are thus preferably connected to the at least one dosing unit (which is connected, for example, to the storage container (13) and to the at least one device c)). Further optionally, the at least one dosing unit, for example connected to the storage container (13), is connected to one containing means (14a) and the at least one device c) is connected to another containing means (14 b). In this case, the at least one device c) is preferably located downstream of the at least one dosing unit.

The at least one device c) and the receiving means (14) are therefore preferably located in the side process flow line (15), or if the side process flow line comprises a side branch, the at least one device c) and the receiving means (14) are located in a side branch (15b) of the side process flow line.

The at least one device c) and the receiving means (14) are connected to the main process flow line (17) if the at least one process flow line consists of the main process flow line (17), i.e. does not comprise one or more side process flow lines (15), or the at least one device c) and the receiving means (14) are preferably connected to a side branch (17b) of the main process flow line if the main process flow line comprises a side branch.

Thus, the at least one device c) is preferably located downstream of the source of water provided in the process stream line. If the process stream line comprises a main process stream line (17) and a side process stream line (15), the at least one device c) is preferably located downstream of the side process stream line (15), i.e. after the process stream line is branched to form the main process stream line (17) and the side process stream line (15).

If the main process stream line (17) or the side process stream line (15) comprises branches, the at least one device c) is preferably located downstream of a side branch of the main process stream line (17) or a side branch of the side process stream line (15), i.e. after the main process stream line (17) or the side process stream line (15) is branched to form the respective side branch.

Preferably, the at least one device c) is preferably located upstream of the vessel, more preferably the reactor tank (1).

Further optionally, the at least one device c) is connected to the container, more preferably to the recirculation device, said recirculation device being adapted for recirculating air or process fluid through at least a part of the surface of the at least one submerged membrane module from the bottom to the top direction of the at least one submerged membrane module and/or the container.

d) The method comprises the following steps A vessel connected to the process stream line

According to d) of the apparatus of the invention, the apparatus comprises a vessel connected to the at least one process stream line via an inlet.

The vessel may be known to those skilled in the art and is typically used to mix water with at least one alkaline earth metal carbonate-containing material and CO₂Or pK_aValue of<5, and/or mixing the acids. Preferably, the container is configured such that the combining and/or mixing can be performed under mixing and/or homogenization conditions.

The vessel is, for example, a reactor tank (1). Such tanks are well known to those skilled in the art and are available from a wide range of suppliers.

In particular, the vessel, preferably the reactor tank (1), can be configured such that during the processThe water provided in the flow line is mixed with the at least one alkaline earth metal carbonate-containing material and CO₂Or pK_aValue of<5 in any order, for example to obtain an aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate.

In one embodiment, the vessel, preferably the reactor tank (1), can be configured such that the filling level (11) in the vessel, preferably the reactor tank (1), and/or the pressure (8) in the vessel, preferably the reactor tank (1), is measured.

It is understood that the dissolution rate of the alkaline earth carbonate in the liquid phase (i.e. water) to obtain an aqueous suspension comprising at least one alkaline earth carbonate-containing material of solution S1 comprising at least one alkaline earth bicarbonate depends on the carbon dioxide or pK dosed_aValue of<5, but also on temperature, pH, pressure, initial alkaline earth carbonate concentration in the suspension and carbon dioxide or pK_aValue of<A dosing rate of 5 (at 25 ℃) of the acid into the aqueous suspension comprising the at least one alkaline earth metal carbonate-containing material.

Preferably, the vessel, preferably the reactor tank (1), is configured such that the concentration of carbon dioxide in the aqueous suspension S1 comprising at least one alkaline earth metal bicarbonate obtained in the vessel is between 10 and 1500mg/l, more preferably between 20 and 1000mg/l and most preferably between 50 and 400 mg/l.

Additionally or alternatively, the vessel, preferably the reactor tank (1), may be configured such that the CO used to produce 1mol of the at least one alkaline earth bicarbonate in the aqueous suspension S1 obtained in the vessel₂The amount (in mol) is from 1.0 to 6.0mol, preferably from 1.0 to 3.0mol and most preferably from 1.0 to 2.0 mol.

It is to be understood that the aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate obtained in the vessel preferably has an earth alkali metal concentration, calculated as earth alkali hydrogen carbonate, of 20-1000mg/l, preferably 50-600mg/l and most preferably 80-400 mg/l. In one embodiment, the aqueous suspension S1 obtained in the vessel comprising at least one earth alkali hydrogen carbonate (being calcium bicarbonate) has a calcium metal concentration, calculated as calcium bicarbonate, of 20-1000mg/l, preferably 50-600mg/l and most preferably 80-400 mg/l.

As described above, an aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate is obtained in the vessel, preferably reactor tank (1).

The aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate obtained in the vessel, preferably reactor tank (1), also comprises undissolved solid particles of the at least one earth alkali carbonate-containing material, and thus the aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate is subjected to a filtration step.

In view of this, the aqueous suspension S1 comprising at least one alkaline earth metal bicarbonate obtained in the vessel, preferably reactor tank (1), preferably has a turbidity value of more than 10NTU, more preferably the aqueous suspension S1 comprises visible solids, i.e. is opaque.

"turbidity" in the meaning of the present invention describes the blurring or turbidity of a fluid caused by individual particles (suspended solids) that are not normally visible to the naked eye. The measurement of turbidity is a key test of water quality and can be performed with a turbidimeter. The Turbidity Units from a calibrated turbidimeter for use in the present invention are defined as Nephelometric Turbidity Units (NTU).

In one embodiment of the present invention, the aqueous suspension S1 comprising at least one alkaline earth metal bicarbonate obtained in the vessel, preferably reactor tank (1), preferably has a solids content of 0.01 to 10.0% by weight, more preferably 0.5 to 10.0% by weight and most preferably 1.2 to 8.0% by weight, based on the total weight of the aqueous suspension S1.

Thus, one particular requirement of the apparatus of the invention is: the vessel, preferably the reactor tank (1), is configured such that the at least one submerged membrane module is located in the vessel for filtering at least a part of the aqueous suspension S1 by: passing the aqueous suspension S1 through the at least one submerged membrane module to obtain an aqueous solution S2 comprising at least one alkaline earth bicarbonate.

In one embodiment, water is combined with at least one alkaline earth metal carbonate-containing material and CO₂Or pK_aValue of<The combining and/or mixing of the acids of 5 and the filtration of at least a portion of the aqueous suspension S1 may be performed in the same vessel, preferably the reactor tank (1). Alternatively, water is combined with at least one alkaline earth metal carbonate-containing material and CO₂Or pK_aValue of<The combining and/or mixing of the acids of 5 can be carried out in one vessel, preferably reactor tank (1), and the filtration of at least a portion of the aqueous suspension S1 can be carried out in another vessel, preferably reactor tank (1 a). In this embodiment, the vessel in which the filtration of at least a portion of the aqueous suspension S1 is carried out, preferably the reactor tank (1a), is located in a vessel in which the filtration of water with at least one alkaline earth metal carbonate-containing material and CO is carried out₂Or pK_aValue of<5, preferably the reactor tank (1).

Preferably, the water is mixed with at least one alkaline earth metal carbonate-containing material and CO in view of reduced overall energy consumption and higher cost efficiency₂Or pK_aValue of<The combining and/or mixing of the acids of 5 and the filtration of at least a portion of the aqueous suspension S1 may be performed in the same vessel, preferably the reactor tank (1). The apparatus therefore preferably comprises a vessel, preferably a reactor tank (1).

One particular requirement of the process of the invention is that: at least a portion of the aqueous suspension S1 is filtered through at least one submerged membrane module (2). Preferably, the entire amount of the aqueous suspension S1 is filtered through at least one submerged membrane module (2).

The vessel is thus configured such that at least one submerged membrane module (2) is located in the vessel, preferably the reactor tank (1).

The at least one submerged membrane module may be any type of submerged membrane module known to the person skilled in the art and typically used for filtering sludge and aqueous suspensions containing minerals, pigments and/or fillers. For example, submerged membrane modules from Toray Industries, Inc.

The at least one submerged membrane module (2) (i.e. membrane) preferably has a pore size of<1 μm, and more preferably<0.1 μm, such as 0.04-0.9 μm, for example about 0.04 μm or 0.08 μm. The at least one submerged membrane module (2) is preferably made of ceramic, polymer or other synthetic material. For example, the at least one submerged membrane module (2) comprises a membrane made of a material selected from the group consisting of: sintered materials, porous ceramics, synthetic polymers such as polyethylene, polypropylene, polysulfone, polyvinylsulfone, polyvinylidene fluoride (PVDF) orAnd mixtures thereof. In one embodiment, the at least one submerged membrane module (2) further comprises fibers or non-woven fabrics, such as fibers or non-woven fabrics made of materials selected from the group consisting of: synthetic polymers such as polyethylene, polypropylene, polyester or mixtures thereof.

It is to be understood that the number of the at least one submerged membrane module (2) depends on the size of the apparatus. One skilled in the art will adapt this number of submerged membrane modules according to the particular equipment size used.

The at least one submerged membrane module (2) preferably has a high flux, i.e. a high flow rate per unit membrane area and time (flux ═ l/(m)²h) ). For example, the at least one submerged membrane module (2) has a value ≧ 10 l/(m)²h) Preferably 50 to 150 l/(m)²h) And most preferably 80 to 150 l/(m)²h) The flux of (c).

Preferably, the at least one submerged membrane module (2) is arranged such that air or process fluid is recirculated (5) through at least a portion of the surface of the at least one submerged membrane module. This has the advantage that: CO 2₂Can be efficiently introduced into the vessel, preferably the reactor tank (1), for increasing the content of at least one alkaline earth metalEfficiency of formation of aqueous suspension of bicarbonate S1. Furthermore, such an arrangement may result in cleaning of the at least one submerged membrane module (2), which is achieved by cross-flow aeration, which may reduce fouling of the at least one submerged membrane module (2). Furthermore, this arrangement has the benefit of maintaining a uniform suspension and preventing undissolved particles from settling.

In one embodiment, air or process fluid is recirculated (5) through at least a portion of the surface of the at least one submerged membrane module (2) from the bottom to the top direction of the at least one submerged membrane module (2) and/or the vessel, preferably reactor tank (1), preferably the at least one submerged membrane module (2) and the vessel, preferably reactor tank (1).

Thus, the vessel preferably comprises recirculation means configured such that air or process fluid is recirculated (5) through at least a portion of the surface of the at least one submerged membrane module (2) from the bottom to the top direction of the at least one submerged membrane module (2) and/or the vessel, preferably the reactor tank (1).

To understand, CO₂Or acid (4) is preferably added to the air or process fluid which is recirculated (5) through at least a portion of the surface of the at least one submerged membrane module (2).

If air or process fluid is recirculated through at least a part of the surface of the at least one submerged membrane module, preferably the vessel, preferably the reactor tank (1), is sealed and air at the top of the vessel, preferably the reactor tank (1), is used as feed and reintroduced (5) at the bottom of the vessel, preferably the reactor tank (1). The vessel is therefore preferably a sealed reactor tank (1).

It is to be understood that the recirculation device is preferably independent of the side process stream line (15) or the main process stream line (17), i.e. the inlet and outlet of the recirculation device are connected to the vessel (preferably reactor tank (1)) at a different location than the inlet and outlet of the side process stream line (15) or the main branch (15a) of the side process stream line or the side branch (15b) of the side process stream line or the main process stream line (17) or the main branch (17a) of the main process stream line or the side branch (17b) of the main process stream line.

Further requirements are: the vessel, preferably the reactor tank (1), is connected to the at least one process stream line via an inlet. Further optionally, the vessel, preferably the reactor tank (1), comprises at least one outlet for releasing the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate from the vessel, preferably the reactor tank (1). Thus, the inlet connected to the at least one process stream line and the outlet or container for releasing the aqueous solution S2, preferably the reactor tank (1), are preferably independent of the inlet and outlet of the recirculation device, i.e. they are connected at different positions from each other. Preferably, therefore, the vessel, preferably the reactor tank (1), is configured such that the outlet for releasing the aqueous solution S2 is connected to the permeate side of the at least one submerged membrane module (2).

In one embodiment, the vessel, preferably the reactor tank (1), is configured such that the at least one submerged membrane module (2) can be cleaned.

For example, the vessel, preferably the reactor tank (1), is configured such that a backwash of the at least one submerged membrane module can be performed.

The term "backwashing" in the meaning of the present invention refers to the addition of water and/or chemicals from the other side of the at least one submerged membrane module (2), i.e. from the permeate side, to the feed side of the at least one submerged membrane module and/or vessel for cleaning the at least one submerged membrane module (2).

For example, backwashing of the at least one submerged membrane module (2) may be performed using water. If the method of the invention comprises backwashing the at least one submerged membrane (2) with water, the backwashing may be performed every 5 to 60 minutes, such as 10 to 15 minutes. Additionally, CO may be reacted₂Or pK_aValue of<5 (at 25 ℃) of an acid was added to the water. In such embodiments, backwashing may be performed once or twice a weekNext, the process is carried out.

It is to be understood that the present apparatus can be operated in batch mode, semi-continuous mode or continuous mode.

The expression "semi-continuous process" in the meaning of the present application refers to a process operating in continuous mode but with intermittent interruptions, for example for carrying out a backwash of the at least one submerged membrane module (2).

The aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention preferably has a carbon dioxide concentration of 0.001 to 300mg/l, more preferably 0.1 to 150mg/l, most preferably 0.5 to 50.

It is to be understood that the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention preferably has an earth alkali metal concentration, calculated as earth alkali hydrogen carbonate, of from 20 to 1000 mg/l. Preferably, the aqueous solution S2 containing at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention has an earth alkali metal concentration, calculated as earth alkali hydrogen carbonate, of from 50 to 500mg/l and more preferably from 80 to 300 mg/l.

In one embodiment, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention comprises calcium bicarbonate, the solution having a calcium metal concentration, calculated as calcium bicarbonate, of between 20 and 1000mg/l, preferably between 50 and 500mg/l and more preferably between 80 and 300 mg/l.

In a further alternative embodiment, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention comprises magnesium hydrogen carbonate, the solution having a magnesium metal concentration, calculated as magnesium hydrogen carbonate, of from 20 to 1000mg/l, preferably from 50 to 400mg/l and more preferably from 80 to 300 mg/l.

Alternatively still, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention comprises calcium hydrogen carbonate and magnesium hydrogen carbonate, the solution having a total calcium and magnesium metal concentration, calculated as calcium magnesium hydrogen carbonate, of between 20 and 1000mg/l, preferably between 50 and 500mg/l and more preferably between 80 and 300 mg/l.

In one embodiment of the present invention, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the present invention has a dissolved content of the at least one earth alkali hydrogen carbonate of from 0.001 to 2.0% by weight, more preferably from 0.001 to 0.05% by weight and most preferably from 0.001 to 0.03% by weight, based on the total weight of the aqueous solution.

Additionally or alternatively, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the inventive device preferably has a turbidity value below 0.5NTU and more preferably below 0.3 NTU. For example, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention has a turbidity value below 0.2NTU or below 0.1 NTU.

It is to be understood that the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention preferably has a pH value of 6.1 to 8.9 and preferably 6.5 to 8.5.

According to one embodiment, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the inventive device has a german hardness of 1-55 ° dH, preferably 3-30 ° dH and most preferably 4.5-17 ° dH.

For the purposes of the present invention, the German hardness is expressed in "degree German hardness, ° dH". In this respect, the german hardness refers to the total amount of alkaline earth metal ions in the aqueous solution comprising the alkaline earth metal bicarbonate.

Preferably, the aqueous solution comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the present invention has a german hardness that is at least 3 ° dH, more preferably at least 5 ° dH, higher than the german hardness of the water provided in the process stream line.

In one embodiment, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention is suitable as mineralized water. This is preferably the case if the apparatus does not comprise one or more side process stream lines (15). That is to say, if the plant comprises only a main process stream line (17), the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the plant of the invention is mineralized water.

Alternatively, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention is suitable for the mineralization of water. For example, the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the invention is suitable for desalination or mineralization and/or stabilization of natural soft water. This is preferably the case if the apparatus comprises one or more side process stream lines (15).

For example, an aqueous solution S2 comprising at least one earth alkali hydrogen carbonate passing through the apparatus of the invention is transferred (9) from the process stream line (15) to the main process stream line (17) for the mineralization of water.

The water which can be mineralized and/or stabilized by using the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate obtained by the apparatus of the present invention can come from various sources and can be selected from distilled water, industrial water, tap water, desalinated water such as desalinated seawater, brackish water or brine, treated wastewater or natural soft water such as groundwater, surface water or rainfall. Preferably, the water mineralized and/or stabilized by using the aqueous solution S2 containing at least one earth alkali hydrogen carbonate obtained by the inventive device is desalinated water, such as permeate or distillate obtained from a desalination process.

In order to neutralize any remaining "aggressive" carbon dioxide and/or increase the pH to obtain a stable and balanced final water quality, it is preferred to strip the aggressive carbon dioxide, add a base to the mineralized water obtained by the inventive device, or a combination of both.

The apparatus therefore preferably comprises a base dosing device downstream of the vessel, preferably the reactor tank (1), for introducing a base into the aqueous solution S2 comprising at least one earth alkali hydrogen carbonate.

In one embodiment, the alkali dosing device is configured for dosing alkali, preferably provided in water, into the main process stream (17) downstream of the vessel, preferably the reactor tank (1), to adjust the pH of the mineralized water to a range of 7.0 to 9.0 and to form mineralized water having an alkaline earth metal concentration, calculated as alkaline earth metal bicarbonate, of 10-300 mg/l.

For example, the apparatus comprises a base dosing device for introducing a base into the main process stream line (17) downstream of the location where the side process stream line (15) and the main process stream line (17) merge together, preferably for introducing a base into a mixture of an aqueous solution S2 comprising at least one earth alkali hydrogen carbonate together with water in the main process stream line (17).

The alkali dosing device for introducing alkali is preferably configured for introducing alkali metal hydroxide and/or alkaline earth metal hydroxide. More preferably, the base dosing device for introducing the base is configured for introducing the base, which is an alkali metal hydroxide and/or an alkaline earth metal hydroxide, selected from calcium hydroxide and/or magnesium hydroxide and/or sodium hydroxide, such as calcium hydroxide or magnesium hydroxide or sodium hydroxide, such as calcium hydroxide.

For example, the base dosing device for introducing the base is preferably configured for introducing the weight median particle size d₅₀An alkaline earth metal hydroxide of 0.1 to 100.0. mu.m, preferably 0.2 to 50.0. mu.m, more preferably 0.3 to 25.0. mu.m, and most preferably 0.5 to 10.0. mu.m.

In one embodiment of the invention, the base as alkaline earth metal hydroxide has a thickness of 0.01 to 200.0m²A/g and preferably from 1.0 to 100.0m²BET specific surface area/g, measured by nitrogen adsorption using the BET isotherm (ISO 9277: 2010).

The alkali dosing device for introducing alkali is preferably configured for introducing alkali metal hydroxide and/or alkaline earth metal hydroxide such that the concentration of alkali metal hydroxide and/or alkaline earth metal hydroxide added to the mineralized water is 0.1-100mg/l and preferably 0.5-10 mg/l.

The base is preferably provided in water. Thus, the base dosing device for introducing the base is preferably configured for introducing the base in the form of a solution or suspension. If the base as alkali metal hydroxide and/or alkaline earth metal hydroxide is in the form of a solution or suspension, the content of the alkali metal hydroxide and/or alkaline earth metal hydroxide is preferably from 0.5% by weight to 50% by weight, preferably about 20% by weight, based on the total weight of the solution or suspension.

The alkali metal hydroxide and/or alkaline earth metal hydroxide solution or suspension may be produced in situ or separately from the process of the invention. If the alkali metal hydroxide and/or alkaline earth metal hydroxide solution or suspension is prepared separately from the apparatus according to the invention, the alkali metal hydroxide and/or alkaline earth metal hydroxide solution or suspension is preferably not prepared from water which is provided in the process stream. Alternatively, the alkali metal hydroxide and/or alkaline earth metal hydroxide solution or suspension is prepared using water provided in the process stream.

The pH of the mineralized water is adjusted to 7.0-9.0 by adding a base, preferably an alkali metal hydroxide and/or an alkaline earth metal hydroxide, to the mineralized water in the main process stream (17). Preferably, the pH of the mineralized water is adjusted to 7.2-8.9 and preferably 7.8-8.4. It is understood that pH adjustment depends on the level of mineralization and the target final water quality.

In one embodiment, a portion of the water provided in the process stream line forms the main process stream (17) and the remaining portion of the water forms the one or more side process stream lines (15). Thus, the one or more side process stream lines (15) are connected to the main process stream line (17), preferably the one or more side process stream lines (15) are connected to the main process stream line (17) through an inlet and an outlet.

In one embodiment, the outlet of the one or more side process stream lines (15) is preferably located at the main process stream (17) downstream of the inlet of the one or more side process stream lines (15).

A further aspect of the invention relates to the use of an apparatus as defined herein for the preparation of an aqueous solution comprising at least one earth alkali hydrogen carbonate.

Another aspect of the invention relates to the use of a device as defined herein for the mineralization and/or stabilization of water. The water is preferably desalinated water or naturally soft water.

With regard to the definition of the apparatus and its preferred embodiments, reference is made to the statements provided above in the discussion of the technical details of the apparatus according to the invention for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate.

Drawings

List of reference symbols:

(1): reactor tank

(2): immersed membrane (Module)

(3): product storage tank

(4): carbon dioxide injection

(5): recirculating air

(6): pressure measurement of recirculated air

(7): pressure measurement in a reaction tank

(8): pressure measurement in aqueous solutions

(9): aqueous solution S2

(10): flow measurement of aqueous solutions

(11): level measurement in a reactor tank

(12): turbidity measurement in aqueous solutions

(13): storage container for calcium carbonate

(14): receptacle for preparing calcium carbonate suspensions

(15): side process stream line supplying water to the process

(16): suspensions of micronized calcium carbonate

(17): main process flow line

(17a) The method comprises the following steps Main branch of main process flow line

(17b) The method comprises the following steps Side branch of main process flow line

(18): pH measurement of mixed water stream

(19): conductivity measurement of mixed water streams

(20): for Ca (OH)₂Storage tank of

(21)：Ca(OH)₂Dosing process stream

(22): pH measurement of the final water stream

(23): final water flow conductivity measurement

(24): final treated water stream

(25): calcium carbonate dosing screw feeder

Fig. 1 relates to an apparatus suitable for carrying out the general process according to the invention.

Figure 2 relates to an apparatus suitable for carrying out the mineralization method according to the present invention.

Figure 3 relates to an apparatus suitable for carrying out mineralization with a pH adjustment method according to the present invention.

Fig. 4 relates to a schematic view of an apparatus comprising only a main process stream line (17) and wherein a dosing unit for dosing calcium carbonate is connected to a vessel (1) comprising submerged membrane modules (2).

Fig. 5 relates to a schematic view of an apparatus comprising only a main process flow line (17) and wherein the dosing unit is configured such that calcium carbonate is dosed directly into the main process flow line (17).

Fig. 6 relates to a schematic view of an apparatus which comprises only a main process flow line (17) and in which a dosing unit for dosing calcium carbonate is connected to a receiving vessel (14) for preparing a calcium carbonate suspension.

Fig. 7 relates to a schematic view of an apparatus comprising a main branch (17a) of a main process flow line and one side branch (17b) of the main process flow line, wherein a dosing unit for dosing calcium carbonate is connected to a receiving device (14) for preparing a calcium carbonate suspension, which receiving device (14) is located in the side branch (17b) of the main process flow line.

Fig. 8 relates to a schematic view of an apparatus comprising a main branch (17a) of a main process flow line and one side branch (17b) of the main process flow line, wherein the dosing unit is configured such that calcium carbonate is dosed directly into the side branch (17b) of the main process flow line.

Fig. 9 relates to a schematic view of an apparatus comprising a main process stream line (17) and a side process stream line (15), wherein a dosing unit for dosing calcium carbonate is connected to a vessel (1) comprising submerged membrane modules (2), which is located in the side process stream line (15).

Fig. 10 relates to a schematic view of an apparatus comprising a main process stream line (17) and a side process stream line (15), wherein the vessel (1) comprising the submerged membrane module (2) is located in the side process stream line (15) and the dosing unit is configured such that calcium carbonate is dosed directly into the side process stream line (15).

Fig. 11 relates to a schematic view of an apparatus comprising a main process flow line (17) and a side process flow line (15), wherein a container (1) comprising an immersed membrane module (2) and recirculation air (5) is located in the side process flow line (15) and a dosing unit for dosing calcium carbonate is connected to a containing appliance (14) for preparing a calcium carbonate suspension, which containing appliance (14) is located in the side process flow line (15). The figure also shows the effect on Ca (OH)₂A dosing device (21) for dosing alkali.

FIG. 12 relates to a schematic diagram of an apparatus comprising a main process stream line (17), a side processA main branch (15a) of the flow line and a side branch (15b) of the side process flow line, wherein a dosing unit for dosing calcium carbonate is connected to a receiving device (14) for preparing a calcium carbonate suspension, which receiving device (14) is located in the side branch (15b) of the side process flow line. The figure also shows a vessel (1) comprising submerged membrane modules (2) and recirculation air (5) in the main branch (15a) of the side process flow line, and for Ca (OH)₂A dosing device (21) for dosing alkali.

Fig. 13 relates to a schematic view of an apparatus comprising a main process flow line (17), a main branch (15a) of a side process flow line and a side branch (15b) of a side process flow line, wherein the dosing unit is configured such that calcium carbonate is dosed directly into the side branch (15b) of the side process flow line. The figure also shows a vessel (1) comprising submerged membrane modules (2) and recirculation air (5) in the main branch (15a) of the side process flow line, and for Ca (OH)₂A dosing device (21) for dosing alkali.

Detailed Description

The scope and benefits of the present invention will be better understood based on the following examples, which are intended to illustrate certain embodiments of the invention and are not limiting.

Examples

1. Measuring method

The measurement method used in the examples is described below.

pH of aqueous suspensions or solutions

The pH of the suspension or solution was measured using a WTWMulti 3420pH meter with integrated temperature compensation and WTWWTW SenTix940pH probe. Calibration of the pH electrodes was performed using standards at pH 4.01, 7.00, and 9.21. The reported pH value is the endpoint value detected by the instrument (endpoint when the measured signal differs from the average over the first 6 seconds by less than 0.1 mV).

Solids content of aqueous suspensions

Moisture Analyser

The solids content (also referred to as "dry weight") was determined using the Moisture Analyser HR73 from Mettler-Toledo, Switzerland under the following settings: 3, standard drying and 5-20g of product are automatically cut off at the temperature of 120 ℃.

Particle size distribution (diameter) of particulate material<Mass% of particles of X) and weight median diameter (d)₅₀)

The weight particle diameter and the particle diameter mass distribution of the particulate material are measured by sedimentation, which is an analysis of the sedimentation behavior in a gravitational field. The Sedigraph from Micromeritics Instrument Corporation was used^TM5120 or Sedigraph^TM5100 measurement is carried out.

Methods and apparatus are known to those skilled in the art and are commonly used to determine the particle size of fillers and pigments. At 0.1% by weight Na₄P₂O₇Is measured in an aqueous solution of (a). The samples were dispersed using a high speed stirrer and ultrasound.

Turbidity of aqueous suspension of solution

Turbidity was measured using a Hach Lange 2100AN IS laboratory turbidimeter and calibrated using stabcl turbidity standards <0.1, 20, 200, 1000, 4000, and 7500NTU (Formazine standards).

Electrical conductivity of

Conductivity at 25 ℃ Using a cell equipped with a corresponding Mettler Toledo conductivity expansion cell and Mettler ToledoMettler Toledo Seven Multi Instrument of 741 conductivity probe.

The instrument was first calibrated in the relevant conductivity range using a commercially available conductivity calibration solution (from mettler toledo). The effect of temperature on conductivity is automatically corrected by a linear correction mode. The measured conductivity is reported as a reference temperature of 20 ℃. The conductivity values reported are the endpoint values detected by the instrument (endpoint when the measured conductivity differs from the average value in the last 6 seconds by less than 0.4%).

Temperature of

The temperature was measured using a handheld WTW probe from Xylem Analytics.

Hardness of aqueous solution

Determination of the ion involved in the hardness of the water, Ca, by titration with the chelating agent ethylenediaminetetraacetic acid (EDTA-disodium salt 0.01M)²⁺(aq) and Mg²⁺(aq). To buffer the pH constant at 10, NH was used₃-NH₄And (4) Cl buffer solution. Titration using Eriochrome Black T as indicator confirmed the results due to Ca²⁺(aq) and Mg²⁺(aq) total hardness caused by ions until the solution changed from wine red to sky blue. The amount of total hardness is calculated by the following equation:

hardness (EDTA volume (ml) × 0.01 × 100.08 × 1000/(sample volume (ml))

Alkalinity of aqueous solution

The alkalinity of the aqueous solution was determined by titrating the sample with a 0.1M hydrochloric acid solution. The endpoint of the titration was reached at a constant pH of 4.3. The amount of alkalinity is calculated by the following equation:

alkalinity ═ acid volume (ml) x 0.1x 100.08x 1000/(2 x sample volume (ml))

Acidity of aqueous solution

By titration of free CO with 0.01M sodium hydroxide solution₂To determine the acidity of the aqueous solution. The endpoint of the titration was reached at a constant pH of 8.3. Free CO₂The amount of (d) is calculated by the following equation:

free CO₂NaOH volume (ml) x 0.01x 44.01x 1000/sampleProduct volume (ml)

Langlier Saturation Index (LSI)

The Langelier Saturation Index (LSI) describes the tendency of an aqueous liquid to form scale or become corrosive, with positive LSI indicating a tendency to form scale and negative LSI indicating a corrosive nature. The equilibrium langeril saturation index (i.e., LSI ═ 0) thus means that the aqueous liquid is in chemical equilibrium. LSI is calculated as follows:

LSI＝pH–pH_s，

wherein the pH is the actual pH of the aqueous liquid and the pH is_sIs CaCO₃pH of the aqueous liquid at saturation. The pH can be estimated as follows_s：

pH_s＝(9.3+A+B)-(C+D)，

Wherein A is a numerical indicator of the Total Dissolved Solids (TDS) present in the aqueous liquid, B is a numerical indicator of the temperature of the aqueous liquid in K, C is CaCO in mg/l₃A numerical indicator of the calcium concentration of the aqueous liquid, and D is as mg/l CaCO₃A numerical indicator of the alkalinity of the aqueous liquid. The parameters a to D are determined using the following equations:

A＝(log₁₀(TDS)–1)/10,

B＝-13.12×log₁₀(T+273)+34.55,

C＝log₁₀[Ca²⁺]–0.4,

D＝log₁₀(TAC)，

wherein TDS is total dissolved solids in mg/l, T is temperature in ℃, [ Ca ]²⁺]In mg/l CaCO₃Calcium concentration of the aqueous liquid and TAC in mg/l CaCO₃The alkalinity of the aqueous liquid is measured.

2. Examples of the embodiments

The equipment of the invention-preparation of calcium bicarbonate water solution

A general process flow diagram of an apparatus according to the present invention is shown in fig. 1. The device comprises an inner part with a thickness of 50m²A reactor tank (1) for submerged membranes (2), a calcium carbonate storage silo (13) with a dosing screw feeder and a holding device (14) for preparing a calcium carbonate suspension.

A solution of calcium bicarbonate (9) is produced in the permeate stream and this can be used to increase the mineral content and alkalinity of the other stream.

Feed water is obtained from a reverse osmosis system, producing water having the following water specifications:

sodium: <1mg/l

Chloride: <2mg/l

Calcium: 8mg/l

Magnesium: <1mg/l

Alkalinity: 12mg/l (as CaCO)₃Meter)

^odH：1.12

pH value: 6.9

Conductivity: 24 mu S/cm

The calcium bicarbonate solution can be produced using the above-described apparatus in the following manner: the reactor tank (1) is initially filled with a 5.0% by weight calcium carbonate suspension to a defined volume, determined by level measurement (11) in the reactor tank, which covers the surface of the submerged membrane. The blower begins to recirculate a volume of air (5) from the top of the reactor tank (1) to the diffuser located at the bottom of the submerged membrane (2) to ensure that a uniform suspension is maintained within the reactor tank (1) and to provide some cleaning effect to the submerged membrane (2). The air volume (5) is recirculated at a rate of about 200 times per hour. A controlled amount of carbon dioxide is added to the air stream at (4). The carbon dioxide-loaded recirculation air creates turbulence through the submerged membrane (2) from the bottom to the top of the reactor tank (1) and the carbon dioxide is transferred from the air stream to the calcium carbonate suspension, increasing the amount of carbon dioxide dissolved in the suspension. The reaction between calcium carbonate and dissolved carbon dioxide allows the formation of an alkaline calcium bicarbonate solution in the reactor tank (1). At the same time, calcium carbonate is added from the storage silo (13) to the containing vessel (14) for preparing a calcium carbonate suspension within the containing vessel (14). A loss-in-weight screw feeder was used to accurately measure the amount of calcium carbonate added. Water was also added to the tank and a mixer was used to produce a homogeneous suspension of known solids content. The suspension (16) of micronized calcium carbonate is then transferred into the reactor tank (1) at a rate equal to the amount of calcium carbonate dissolved by reaction with carbon dioxide, so that the total amount of calcium carbonate not dissolved inside the reactor tank (1) remains unchanged. An aqueous solution of filtered permeate S2(9) was extracted from the reactor tank (1) through the submerged membrane (2).

Pilot run Unit (Start-up pilot unit)

Using natural calcium carbonate powder (From Omya International AG, OrgonFance, d₅₀3 μm) as starting material in a pilot plant of the plant according to the invention. The reactor (1) was filled with 900l of the prepared 5% by weight suspension of calcium carbonate powder, which was carried out by means of a level control (11). Recirculating air flow (5) fan at 10m³H starts for regeneration of the membrane by turbulent flow. The overpressure of the air flow is measured by (6).

Example 1:

to produce a high load of concentrate (-250 mg/l alkalinity), 99g of carbon dioxide (4) was dosed into the recirculating air stream over 1 hour. Continuous production was started at the end of the first hour recycle time. During continuous production, 250mg/l calcium carbonate suspension (16) was added to the reactor (1) for continuous dissolution of calcium carbonate in the reactor tank (1). At the same time, a clear aqueous solution S2(9) was extracted through the submerged membrane (2) at a concentration of 250mg/l calcium bicarbonate, measured as calcium carbonate, using a two-way dosing pump. The two ratios (suspension of micronized calcium carbonate (16) and aqueous solution (9)) are controlled by level measurement (11) in the reactor tank (1) and flow meter measurement (10) of the aqueous solution S2 (9). The initial setting of the ratio depends on the achievable membrane flux rate and is measured as the transmembrane pressure (8). The quality of the aqueous solution S2(9) was controlled by turbidity measurements (12) and titration.

The operating conditions and water quality results are given in tables 1 and 2 below.

Table 1: the process stream of example 1.

Process stream	(16)	(9)	(5)
				Description of the invention	Calcium carbonate suspension	Calcium bicarbonate solution S2	Recirculating air
Flow rate (l/h)	1 250	1 250	20 000
				Solid content (% by weight)	0.025	0	0
Concentration (mg/l)	0	220	110^a

^a: carbon dioxide is dosed into the reactor in equivalents based on the flow rate of water through the reactor.

Table 2: water quality of example 1

Process stream	(9)
		Description of the invention	Calcium bicarbonate solution S2
Alkalinity (mg/l, as CaCO)₃Meter)	220
		Hardness (mg/l, as CaCO)₃Meter)	214
pH	7.4
		Temperature [ deg.C ]]	21.5
Turbidity [ NTU]	0.1

The above-described method using the apparatus according to the invention has a much better energy efficiency than the patent application EP 2623467 a 1. According to Table 4 of EP 2623467A 1, 35l/h of permeate were produced in 4 different experiments from a tubular membrane Module (Microdyne-Module MD063 TP 2N). The suspension in these tests was circulated through the tubular module at a rate of 3200 l/h at a pressure of 1.5 bar to produce this permeate flow. The hydraulic energy required to produce this permeate is thus:

hydraulic energy (W) V x ρ x p

Wherein:

fluid flow velocity (m)³/s)

Rho fluid density (kg/m)³)

Static pressure at pump outlet (kPa)

For the example from patent application EP 2623467 a1, the following inputs are available:

V＝3 200l/h＝8.8e-04m³/s

ρ＝1 000kg/m³(for water, without any other details)

This produced an average of 54l/h of permeate and therefore the power consumption per cubic meter of permeate produced can be calculated as follows:

power/cubic meter 0.133 kW/0.035 m³/h＝3.8kW.h/m³。

Using the apparatus according to the invention and as shown in FIG. 1, a pressure of 50kPa was produced of 1250 l/h-3.47 e-04m³Permeate in s.

The hydraulic energy is thus calculated as follows:

the hydraulic energy (W) is V x ρ x p — 3.47e-04x 1000 x 50 — 17.4W.

This produced an average of 1250l/h of permeate and therefore the power consumption per cubic meter of permeate produced can be calculated as follows:

power/cubic meter 0.0174 kW/1.25 m³/h＝0.014kW.h/m³

The specific power consumption (power consumption per cubic meter of permeate produced) of the invention is therefore more than 270 times less than in the case of patent application EP 2623467 a 1.

CO according to tests with the inventive device described by EP 2623467A 1 and shown in FIG. 1₂Efficiency is calculated as follows:

(free CO in Water₂+ CO dosed₂)/CO₂Molecular weight (final basicity-initial basicity)/CaCO₃Molecular weight

＝(2+110)/44.01g/mol：(220-12)/100.08g/mol＝2.54：2.08＝1.22：1。

CO according to a test carried out with a device according to patent application EP 2623467A 1₂The efficiency is shown as:

110/44.01g/mol：170/100.08g/mol＝2.5：1.7＝1.47：1。

apparatus of the invention-preparation and dosing of an aqueous solution of calcium bicarbonate to increase the mineral and alkalinity content of desalinated water

A general process flow diagram of an apparatus according to the present invention is shown in fig. 2. The device comprises an inner part with a thickness of 50m²A reactor tank (1) for submerged membranes (2), a product reservoir (3), a calcium carbonate storage silo (13) with a dosing screw feeder and a holding device (14) for preparing a calcium carbonate suspension.

A calcium bicarbonate solution is produced in aqueous solution S2(9) and dosed into the main process stream (17) to increase the mineral content and alkalinity of the main process stream.

sodium: <1mg/l

Chloride: <2mg/l

Calcium: 8mg/l

Magnesium: <1mg/l

Alkalinity: 12mg/l (as CaCO)₃Meter)

^odH：1.12

pH value: 6.9

Conductivity: 24 mu S/cm

The above-described apparatus can be used to produce a solution of calcium bicarbonate in a side process stream in the following manner: the reactor tank (1) is initially filled with a 5.0% by weight calcium carbonate suspension to a defined volume, measured by a level measurement (11) in the reactor tank (1), which covers the surface of the submerged membrane (2). The blower begins to recirculate a volume of air (5) from the top of the reactor tank (1) to the diffuser located at the bottom of the submerged membrane (2) to ensure that a uniform suspension is maintained within the reactor (1) and to provide some cleaning effect to the membrane. The air volume (5) is recirculated at a rate of about 200 times per hour. A controlled amount of carbon dioxide is added to the air stream at, for example, location (4). The carbon dioxide-laden recycled air creates turbulence through the submerged membrane (2) from the bottom to the top of the reactor and the carbon dioxide is transferred from the air stream to the calcium carbonate suspension, increasing the amount of carbon dioxide dissolved in the suspension. The reaction between calcium carbonate and dissolved carbon dioxide allows the formation of a calcium bicarbonate solution within the reactor tank. At the same time, calcium carbonate is added from the storage silo (13) to the containing vessel (14) for preparing a calcium carbonate suspension within the containing vessel (14). A loss-in-weight screw feeder was used to accurately measure the amount of calcium carbonate added. Water is also added to the holding vessel (14) and a mixer is used to produce a homogeneous suspension of known solids content. The suspension (16) of micronized calcium carbonate is then transferred into the reactor tank (1) at a rate equal to the amount of calcium carbonate dissolved by reaction with carbon dioxide, so that the total amount of calcium carbonate not dissolved inside the reactor tank (1) remains unchanged. An aqueous solution of filtered permeate S2(9) as a clear concentrated calcium bicarbonate solution is used to add calcium and bicarbonate to the main process stream line (17) by means of a bi-directional dosing pump. The product reservoir (3) is used as a buffer also for the backwash sequence every 10 minutes.

Pilot unit for pilot run

Using natural calcium carbonate powder (From Omya International, Orgon France, d₅₀3 μm) as starting material in a pilot plant. The reactor tank (1) was filled with 900l of the prepared 5% by weight suspension of calcium carbonate powder, which was carried out by level measurement (11) in the reactor tank (1). Recirculating air flow (5) fan at 10m³H starts for regeneration of the membrane by turbulent flow. The overpressure of the air flow is measured by (6).

Example 2:

to produce a high load of concentrate (-250 mg/l alkalinity), 99g of carbon dioxide (4) was dosed into the recirculating air stream over 1 hour. Continuous production was started at the end of the first hour recycle time. During continuous production, 250mg/l calcium carbonate suspension (16) was added to the reactor (1) for continuous dissolution of calcium carbonate in the reactor tank (1). At the same time, a clear aqueous solution S2(9) was extracted at a concentration of 250mg/l of calcium bicarbonate (measured as calcium carbonate) by means of an immersed membrane and discharged into the main stream (17) through the product reservoir (3) via a two-way dosing pump. The two ratios (suspension of micronized calcium carbonate (16) and aqueous solution S2(9)) are controlled by level measurement (11) and flow measurement (10) in the reactor tank (1). The initial setting of the ratio depends on the achievable membrane flux rate and is measured as the transmembrane pressure (8). The quality of the aqueous solution S2(9) was controlled by turbidity measurements (12) and titrations in the aqueous solution (9). The mass of the first blend is measured by pH (18), conductivity (19) and titration of the blended water stream.

The operating conditions and water quality results are given in tables 3 and 4 below.

Table 3: the process stream of example 2.

Table 4: water quality results of example 2

Process stream	(9)	(24)
			Description of the invention	Calcium bicarbonate solution S2	Final water
Alkalinity (mg/l, as CaCO)₃Meter)	220	81
			Hardness (mg/l, as CaCO)₃Meter)	214	85
pH	7.4	7.25
			Temperature [ deg.C ]]	21.5	21
Turbidity [ NTU]	0.1	0

The inventive device-preparation and dosing of an aqueous solution of calcium bicarbonate followed by pH adjustment to increase the mineral and alkalinity content of the desalinated water and to stabilize it in terms of its saturation index

A general process flow diagram of an apparatus according to the present invention is shown in fig. 3. The device comprises an inner part with a thickness of 50m²A reactor tank (1) for submerged membranes (2), a product storage tank (3), a calcium carbonate storage silo (13) with a dosing screw feeder and a holding device (14) for preparing a calcium carbonate suspension, as well as a calcium hydroxide storage tank (20) and a dosing system.

A calcium bicarbonate solution is produced in aqueous solution S2(9) and dosed into the main process stream (17) to increase the mineral content and alkalinity of the main process stream (17). After dosing the calcium bicarbonate solution, a 5.0% by weight and high purity calcium hydroxide suspension (21) is dosed in the main process stream (17) to produce the desired final water quality of the final treated water stream (24).

Feed water is provided in all process streams, the feed water being obtained from a reverse osmosis system, yielding water with the following water specifications:

sodium: <1mg/l

Chloride: <2mg/l

Calcium: 8mg/l

Magnesium: <1mg/l

Alkalinity: 12mg/l (as CaCO)₃Meter)

^odH：1.12

pH value: 6.9

Conductivity: 24 mu S/cm

The above-described apparatus can be used to produce a solution of calcium bicarbonate in a side process stream in the following manner: the reactor tank (1) is initially filled with a 5.0% by weight calcium carbonate suspension to a defined volume, measured by a level measurement (11) in the reactor tank (1), which covers the surface of the submerged membrane (2). The blower begins to recirculate a volume of air (5) from the top of the reactor tank (1) to the diffuser located at the bottom of the submerged membrane (2) to ensure that a uniform suspension is maintained within the reactor tank (1) and to provide some cleaning effect to the submerged membrane (2). The volume was recirculated at a rate of about 200 times per hour. A controlled amount of carbon dioxide is added (4) to the air stream. The carbon dioxide-loaded recirculation air creates turbulence through the submerged membrane (2) from the bottom to the top of the reactor tank (1) and the carbon dioxide is transferred from the air stream to the calcium carbonate suspension, increasing the amount of carbon dioxide dissolved in the suspension. The reaction between calcium carbonate and dissolved carbon dioxide allows the formation of a calcium bicarbonate solution in the reactor tank (1). At the same time, calcium carbonate is added from the storage silo (13) to the containing vessel (14) for preparing a calcium carbonate suspension within the containing vessel (14). A loss-in-weight screw feeder was used to accurately measure the amount of calcium carbonate added. Water was also added to the tank and a mixer was used to produce a homogeneous suspension of known solids content. The suspension (16) of micronized calcium carbonate is then transferred into the reactor tank (1) at a rate equal to the amount of calcium carbonate dissolved by reaction with carbon dioxide, so that the total amount of calcium carbonate not dissolved inside the reactor tank (1) remains unchanged. An aqueous solution of filtered permeate S2(9) as a clear concentrated calcium bicarbonate solution is used to add calcium and bicarbonate to the main process stream (17) by a bi-directional dosing pump. The product reservoir (3) is used as a buffer also for the backwash sequence every 10 minutes. A second dosing pump is used to add the calcium hydroxide suspension stored in a storage tank (20), for example at location (21), to the main process stream (17).

Pilot unit for pilot run

Using natural calcium carbonate powder (From Omya International, Orgon France, d₅₀3 μm) and calcium hydroxide suspension (d: (d)Precal 72, concentration in water 20% by weight) as starting material in the pilot plant.The product (Precal 72) is a highly reactive 20% by weight calcium hydroxide suspension, diluted to 5% by weight (21) and dosed directly into the final treated water stream (24) for efficient pumping. The reactor tank (1) was filled with 900l of the prepared 5% by weight suspension of calcium carbonate powder, which was carried out by level measurement (11) in the reactor tank 1. Recirculating air flow (5) fan at 10m³H starts for regeneration of the membrane by turbulent flow. The overpressure of the air flow is measured by (6).

Example 3:

to produce a high load of concentrate (-250 mg/l alkalinity), 99g of carbon dioxide (4) was dosed into the recirculating air stream over 1 hour. Continuous production was started at the end of the first hour recycle time. During continuous production, 250mg/l micronized calcium carbonate suspension (16) was added to the reactor tank (1) for continuous dissolution of calcium carbonate within the reactor tank (1). At the same time, a clear aqueous solution (9) was extracted at a concentration of 250mg/l of calcium bicarbonate (measured as calcium carbonate) by means of an immersed membrane (2) and discharged via a two-way dosing pump through a product reservoir (3) into the main process stream (17). The two ratios (suspension of micronized calcium carbonate (16) and aqueous solution S2(9)) were controlled by level measurement (11) in the reactor tank (1) and flow measurement (10) of aqueous solution S2 (9). The initial setting of the ratio depends on the achievable membrane flux rate and is measured as the transmembrane pressure (8). The quality of the aqueous solution (9) is controlled by turbidity measurements (12) and titrations. The mass of the first blend was measured by pH (18), conductivity (19) and titration. In order to achieve the desired final water quality with a langelier saturation index of 0 for the final treated stream (24), a calcium hydroxide suspension (21) from the tank (20) is also dosed into the final treated stream (24).

The operating conditions and water quality results are given in tables 5 and 6 below.

Table 5: the process stream of example 3.

Table 6: water quality results of example 3

Process stream	(9)	(24)
			Description of the invention	Calcium bicarbonate solution S2	Final water
Alkalinity (mg/l, as CaCO)₃Meter)	220	88.5
			Hardness (mg/l, as CaCO)₃Meter)	214	92.5
pH	7.4	7.95
			Temperature [ deg.C ]]	21.5	21
Turbidity [ NTU]	0.1	0

Example 4: use of ceramic membranes in Membrane Calcite Reactors (MCR) according to FIG. 1

4.1 devices

The following devices were used for testing:

"membrane calcite reactor" (MCR) consists of:

a rectangular PVC reactor with a maximum volume of 75l and the required connections,

omicron ceramic SiCMF-0828 silicon carbide immersed membrane module with 0.828m²Is installed in the reactor. Cembrane SiCMF-0828 silicon carbide is a ceramic membrane. Methods for preparing ceramic membranes suitable for use in the present invention are described, for example, in EP 3009182 a 1. The content of patent application EP 3009182 a1 is hereby incorporated by reference.

O sealing the lid of the reactor,

instrument for level control

An instrument for pressure, in particular transmembrane pressure (TMP), monitoring,

a blower system configured to form a blower recirculation loop, consisting of:

a blower operated by a variable speed drive,

omicron from the top of the reactor (connected to the lid) connected blower piping system

-a discharge piping system connected to the diffuser manifold at the bottom of the submerged membrane unit,

osmotic pumps to extract a concentrated solution through a membrane, consisting of:

a pump operated by a variable speed drive,

a flow meter for measuring a flow rate,

a carbon dioxide dosing system consisting of:

omicron carbon dioxide bottle

O pressure regulator to reduce the pressure from 50 to 5 bar of the bottle

Omicron mass flowmeter and control valve to regulate and measure the dosing of carbon dioxide

O dosing connection to blower discharge piping system

A slurry compression (SMD) system, consisting of:

a slurry compression (SMD) tank having an electric stirrer and a tank level instrument,

feed water supplied to the tank, controlled to maintain a level in the tank

A zero-gravity dosing feed system to accurately add a desired amount of micronized calcium carbonate to the SMD tank,

an omicron hopper for supplying micronized calcium carbonate to a loss-in-weight feeder,

a slurry feed pump for dosing the calcium carbonate suspension produced in the SMD tank into a 75l reactor,

o. a dosing hose for connecting a slurry feed pump and a 1800l reactor

A control system that performs the following functions:

o controlling the osmotic pump to achieve the required flow rate

Control of slurry feed pump to ensure reactor level remains unchanged

Run the blower at the required speed.

4.2 procedure:

the following procedure was used for the experiments:

SMD tanks were filled with water and calcium carbonate was dosed into the tanks to produce suspension S1 (according to the setup provided below).

2. The SMD control was placed in an automatic mode so that water would be continually replenished in the SMD tank as the suspension was removed from the tank and calcium carbonate would be continuously dosed to ensure that a consistent suspension of the concentration provided in section 4.3 was produced.

3. 50l of suspension S1 containing 1% micronized calcium carbonate were supplied to a 75l reactor (membrane calcite reactor). In this process, the reactor was supplemented with a suspension of micronized calcium carbonate S1 to ensure a continuous process.

4. The lid of the reactor was closed and a tight seal was ensured.

5. The blower was operated electrically to maintain the micronized calcium carbonate in suspension S1.

6. Carbon dioxide was dosed into the blower recirculation loop according to the setup provided in section 4.3.

7. The osmotic pump was operated at a set rate to provide the desired flow rate and to extract the clarified solution S2 from the reactor tank. The pump speed is varied to achieve a range of flow rates according to the settings provided in section 4.3.

8. The slurry feed pump was operated at a set speed to ensure that the level within the reactor tank remained constant.

9. A sample of the concentrated solution S2 extracted by the osmotic pump was analyzed for the following water qualities by the method described above:

a. alkalinity (mg/l)

b. Total hardness (mg/l)

c. Acidity (in mg/l CO)₂Meter)

pH, conductivity, temperature & turbidity

The operating settings including flow rate, TMP, temperature were recorded for each experiment.

4.3 test setup

The following test set-up was used during the experiment:

table 7: test setup

The results presented in table 8 show that high flux rates (up to 845lmh) can be achieved by using ceramic membranes as the at least one submerged membrane module, and that these high flux rates are achieved by stable and almost constant transmembrane pressure (TMP) values. The flux rate is normalized over TMP (along with temperature) to produce the permeability value of the membrane. The permeability value of the ceramic membrane as the at least one submerged membrane module is fairly constant throughout the flux rate range. As can be seen from table 8, the permeability of the ceramic membrane as the at least one submerged membrane module in this process is in the range of 1100-1790 lmh/bar.

Furthermore, the use of the submerged membrane module results in lower specific energy consumption for blower operation.

79m²Ceramic membrane column of membrane area having a maximum blower air flow rate of 150Nm³And/hr. Using test results showing a stable flux rate of up to 800lmh, such a tower could produce 800lmh by 79m²＝63.2m³Flow rate,/hr. By normalizing this flow rate to the maximum blower air flow rate, the specific flow rate (per Nm) can be displayed³Flow rate of blower air/hr) is per Nm³Air flow rate of blower/hr is 0.421m³Per hr permeate.

In addition to the above benefits, the tests show that very low contact times-as low as 4 minutes-can be achieved by using the at least one submerged membrane module.

And (4) conclusion: tests using a ceramic membrane as the at least one submerged membrane module in a remineralization process have demonstrated that much higher flux rates can be achieved during stable operation. Higher flux rates result in lower specific energy consumption of the blower and reduced contact time of the process, which reduces the overall footprint of the process, which is very important for large scale desalination processes. Furthermore, the increased permeability of the membrane module may provide a reduced pressure drop across the membrane module and thus reduced energy consumption for applications where energy costs are of high importance.

Claims

1. An apparatus for preparing an aqueous solution comprising at least one earth alkali hydrogen carbonate, the apparatus comprising

a) A process flow line for providing water,

c) at least one adapted for feeding CO₂Or pK_aValue of<5 acid additionMeans being provided for adding to at least a part of the water provided in the process flow line or to the aqueous suspension comprising at least one alkaline earth metal carbonate-containing material, for obtaining an aqueous suspension S1 comprising at least one alkaline earth metal bicarbonate, and

2. Device according to claim 1, wherein the at least one dosing unit

i) Connected to a storage container for solid material, and/or

ii) configured such that the at least one alkaline earth metal carbonate-containing material is dosed directly into the water provided in the process stream line, or

iii) is connected to a holding vessel suitable for preparing an aqueous suspension comprising at least one alkaline earth metal carbonate-containing material, wherein the holding vessel is connected to the process flow line via an inlet for introducing water provided in the process flow line and an outlet for releasing the aqueous suspension comprising the at least one alkaline earth metal carbonate-containing material, or

iv) is connected to the container.

3. The apparatus according to claim 1 or 2, wherein the vessel is a reactor tank, preferably a sealed reactor tank.

4. The apparatus according to any one of claims 1-3, wherein the container comprises a recirculation device configured to cause air or process fluid to be recirculated through at least a portion of the surface of the at least one submerged membrane module from the bottom to the top direction of the at least one submerged membrane module and/or container.

5. The apparatus according to any of claims 1-4, wherein the at least one device c)

i) Is configured such that CO₂Or pK_aValue of<5 is dosed directly into the water provided in the process stream, or

ii) is connected to a receptacle suitable for preparing an aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate, wherein the receptacle is connected to the process stream line via an inlet for introducing water provided in the process stream line and an outlet for releasing an aqueous suspension S1 comprising at least one earth alkali hydrogen carbonate, or

iii) to the container, preferably to the recirculation device, which is adapted to recirculate air or process fluid through at least a part of the surface of the at least one submerged membrane module from the bottom to the top direction of the at least one submerged membrane module and/or container.

6. The apparatus of any of claims 1-5, wherein the at least one submerged membrane module

a) Has a pore size <1 μm, and more preferably <0.1 μm, e.g. 0.04-0.9 μm, such as about 0.04 μm or 0.08 μm, and/or

b) Has a content of more than or equal to 10 l/(m)²h) Preferably 50 to 150 l/(m)²h) And most preferably 80 to 150 l/(m)²h) And/or flux of

c) Are made of ceramic, polymer or other synthetic materials.

7. The apparatus of any of claims 1-6, wherein the at least one process stream line comprises one or more main process stream lines.

8. The apparatus according to claim 7, wherein the at least one process stream line comprises two main process stream lines, preferably a main branch of the main process stream line and a side branch of the main process stream line.

9. The apparatus according to claim 8, wherein the at least one dosing unit is located in a side branch of the main process stream line.

10. Apparatus according to claim 8 or 9, wherein the main branch of the main process stream line and the side branches of the main process stream line are configured such that they merge together upstream of the vessel.

11. The apparatus according to any of claims 1-6, wherein the at least one process stream line comprises a main process stream line and one or more side process stream lines, preferably a main process stream line and one or two side process stream lines.

12. The apparatus according to claim 11, wherein the at least one process stream line comprises a main process stream line and two side process stream lines, preferably a main branch of the side process stream line and a side branch of the side process stream line.

13. The apparatus according to claim 11 or 12, wherein the at least one dosing unit is located in the side process stream line or, if present, in the side branch of the side process stream line.

14. Apparatus according to any one of claims 11 to 13, wherein the main branch of the side process stream line and the side branch of the side process stream line are configured such that they merge together upstream of the vessel.

15. Apparatus according to any one of claims 11 to 14, wherein the main process stream line and the side process stream line are configured such that they merge together downstream of the vessel.

16. The apparatus according to any one of claims 1 to 15, wherein the apparatus comprises a base dosing device downstream of the vessel for introducing a base into the aqueous solution S2 comprising at least one alkaline earth metal bicarbonate.

17. An apparatus according to any one of claims 7-15, wherein the apparatus comprises a base dosing device for introducing a base into the main process stream line downstream of the location where the side process stream line and the main process stream line merge together, preferably for introducing a base into a mixture of the aqueous solution S2 comprising the at least one earth alkali hydrogen carbonate together with the water in the main process stream line.

18. Use of the device according to any one of claims 1 to 6 for the preparation of an aqueous solution comprising at least one earth alkali hydrogen carbonate.

19. Use of the device according to any one of claims 1-15 for the mineralization and/or stabilization of water.