RU2841437C1 - Coal slurry classification method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: set of invention relates to dressing of minerals and can be used for processing of anthracites, bituminous or brown coal. Proposed method comprises grading raw coal to produce sludge pulp directed to thickening, sizing, dehydration and extraction of coal concentrate. Produced slurry pulp is classified on multi-deck screen to produce oversize product with 0.5-3.0 mm slurry and undersize product with 0-0.5 mm slurry. Oversize product is supplied for additional dehydration and/or enrichment, and undersize product with sludge of class 0-0.5 mm is supplied to stages of thickening, and/or enrichment, and/or classification. In compliance with another version, undersize product with 0-0.5 mm sludge is fed for reclassification into multi-deck screen to produce oversize and undersize products. In compliance with another version, undersize product is screened for the third time in multi-deck screen to produce oversize and undersize products. In compliance with fourth version, proposed method comprises grading raw coal to produce sludge pulp and slurry pulp in hydraulic cyclone to separate drain and sands. Drain from hydraulic cyclone is classified into oversize and undersize products. Prior to its thickening in thickener, undersize product is directed to classification in multi-deck screen to produce oversize and undersize products. According to the fifth variant, the sands are directed for dehydration and/or enrichment, and for the separation of the coal concentrate from the drain, classification is carried out in a multi-deck screen to produce oversize and undersize products, wherein undersize product is directed to re-classification in multi-deck screen to produce oversize and undersize products.

EFFECT: improving classification efficiency of coal slurry and processability of coal slurry enrichment scheme.

5 cl, 7 dwg

Description

The invention relates to the enrichment of minerals and can be used in the processing of anthracite, hard or brown coal [B03B 7/00, B03B 9/00, B03B 9/06, B03B 5/18].

The state of the art includes a GRAVITATIONAL METHOD FOR REMOVING HIGH-ASH SLIDS FROM A WATER-SLUDGE COAL ENRICHMENT SYSTEM [RU 2407594 C1, 29.06.2009], the technical result of which is preventing the accumulation of sludge in the system and reducing operating costs, increasing the efficiency of removing sludge products, which consists in reducing mutual clogging of products while simultaneously reducing the amount of sludge water in circulation and the amount of equipment, which will reduce specific material costs and energy costs. The gravity method for removing high-ash sludge from the water-sludge coal enrichment circuit includes dry classification by size on a screen, wetting the coal with water with simultaneous forced mixing, wet classification on a screen without adding water with the separation of the oversize product and undersize product with a particle size of 1-0 mm, dewatering the product on a belt vacuum filter, returning clean water to circulation and directing the high-ash sludge to a dump, forced mixing is carried out in an amount selected from the ratio (30-40): 1, while after wet classification on a screen and before dewatering, the undersize product is sent for thickening in a hydrocyclone, which is carried out until the removal of sludge with a solid thickened substance content of at least 35%, and a drain, which is sent for thickening in a plate thickener, the thickened product of which is dewatered on a belt vacuum filter to obtain a filtrate, which is sent together with the plate The thickener thickens it in a sludge pool and drains it. The latter is sent for thickening to a gravity step thickener, producing at the outlet a sludge with a solids content of at least 65% in thickened form and an ash content of 58-62%.

The disadvantage of the analogue is the low efficiency and productivity of coal sludge classification, due to the features of the coal sludge enrichment scheme, in which a hydrocyclone is used.

Also known is a DEVICE FOR ENRICHING COAL SLUDGE [RU 80128 U1, published 27.01.2009], characterized in that it contains a filter centrifuge, the rotor of which is formed by trapezoidal grates, a hydroclassifier, a thickener and a hydrocyclone, successively installed in front of the filter centrifuge, wherein the width of the gap between the grates is twice the size of the boundary grain of the sludge separation. The technical result obtained by implementing the technical solution described in the analogue consists in reducing the waste obtained by burning coal sludge enriched using the developed device. The method implemented using the technical solution declared in the analogue consists in that the ash content of each fraction of coal sludge preliminarily separated by size is determined, the dependence of ash content on the size of the fraction is constructed based on the obtained data, high-ash fractions are separated, which are then removed using a filter centrifuge, a suspension of coal sludge is hydroclassified with the separation of a light fraction of coal sludge as a second target product, the resulting suspension of the light fraction is thickened with subsequent separation of high-ash fractions. Preferably, after enrichment, the low-ash fractions of the sludge are at least partially dehydrated.

The studies presented in the analogue indicate the possibility of obtaining a conditioned concentrate with an ash content of 9.5-10.5% from sludge of class 0-0.5 mm in a volume of 60-70%. The disadvantage of the analogue is the low degree of separation and enrichment of coal sludge.

The closest in technical essence is the METHOD OF BENEFICIATION OF COAL SLUDGE [RU 2297284 C2, 20.04.2007], which includes pulping of the initial raw material with subsequent separation of the granular coal portion from the rock component by hydroclassification in a vertical gravity-type hydroclassifier, in which the separation of the granular coal portion from the rock component is carried out due to the difference in grain size and density of the medium in the ascending flow of water carrying out the suspended rock component, and the capture of the rock component in a thickener, characterized in that the rock component is captured in the thickener using a multifunctional material that acts as a filtering, coagulating, flocculating, sorbing, drainage and water-repellent layer, which, after thickening, is subjected to regeneration with the release of the rock component, and having passed through drainage layer water is returned to the coal washing in the hydroclassifier, completing the circulating cycle, and the enriched granular coal portion obtained in the hydroclassifier is dehydrated in a centrifuge with separation of the centrate in a circulating water storage tank and the extraction of coal concentrate, mixed with a binder in a mixer and sent for granulation with subsequent drying. The technical result of the analogue is an increase in the efficiency of extracting combustible mass into concentrate from coal sludge.

The main technical problem of the prototype is the low efficiency of coal sludge classification due to the design features of the hydrocyclone, causing clogging of the coal concentrate with large rock particles of the coal concentrate and the loss of large low-ash coal particles with waste, as well as the need to use a multifunctional material that is irretrievably lost during the enrichment process. In addition, hydrocyclones are characterized by a number of disadvantages that reduce their reliability and cause a significant cost of the resulting end product, namely, rapid clogging of the discharge nozzles at high density (viscosity) of the pulp and a low degree of separation and enrichment of the coal sludge.

The efficiency of a hydrocyclone depends on many factors. The main ones include: the diameters of the housing, feed, drain and discharge pipes, the angle of the conical part, the pressure at the inlet, the concentration and size of the solid phase particles in the initial product, the difference in the densities of the solid and liquid phases, which ultimately reduces the operating capabilities and manufacturability.

The objective of the invention is to eliminate the shortcomings of analogues and the prototype.

The technical result of the invention consists in increasing the efficiency of coal sludge enrichment and the technological efficiency of the coal sludge enrichment scheme.

The specified technical result is achieved due to the fact that the method of classifying coal sludge is characterized by the fact that the sludge pulp obtained during the classification of run-of-mine coal is thickened, classified and dewatered in a multi-deck screen to obtain oversize and undersize products, from which coal concentrate is isolated.

The specified technical result is achieved due to the fact that the method of classifying coal sludge, characterized by the fact that the sludge pulp obtained during the classification of run-of-mine coal is classified in a hydrocyclone, separating sands and runoff, coal concentrate is isolated from the sands and runoff, while in order to isolate the coal concentrate from the runoff, it is thickened, classified and dewatered in a multi-deck screen to obtain oversize and undersize products, from which coal concentrate is isolated.

The specified technical result is achieved due to the fact that the method of classifying coal sludge is characterized by the fact that the sludge pulp obtained during the classification of run-of-mine coal is classified in a hydrocyclone, the discharge from the hydrocyclone is classified into oversize and undersize products, the undersize product is thickened, classified and dewatered in a multi-deck screen before it is thickened in a thickener.

The specified technical result is achieved due to the fact that the method for classifying coal sludge is characterized by the fact that the sludge pulp obtained during the classification of run-of-mine coal is thickened, classified and dewatered in a multi-deck screen to obtain oversize and undersize products, from which coal concentrate is separated, while for the enrichment of the coal concentrate the undersize product is repeatedly thickened, classified and dewatered in a multi-deck screen.

The specified technical result is achieved due to the fact that the method for classifying coal sludge is characterized by the fact that the sludge pulp obtained during the classification of run-of-mine coal is thickened, classified and dewatered in a multi-deck screen to obtain oversize and undersize products, from which coal concentrate is separated, while the undersize product for enriching the coal concentrate is repeatedly thickened, classified and dewatered in a multi-deck screen.

The specified technical result is achieved due to the fact that the method for classifying coal sludge is characterized by the fact that the sludge pulp obtained during the classification of run-of-mine coal is classified in a hydrocyclone, separating sands and overflow, coal concentrate is isolated from the sands and overflow, while in order to isolate the coal concentrate from the overflow, it is thickened, classified and dewatered in a multi-deck screen to obtain oversize and undersize products, and in order to enrich the coal concentrate, the undersize product is repeatedly thickened, classified and dewatered in a multi-deck screen.

The specified technical result is achieved due to the fact that the method for classifying coal sludge is characterized by the fact that the sludge pulp obtained during the classification of run-of-mine coal is thickened, classified and dewatered in a multi-deck screen to obtain oversize and undersize products, the undersize product for enriching the coal concentrate, the undersize product is thickened, classified and dewatered in a multi-deck screen to obtain oversize and undersize products, and for enriching the coal concentrate, the undersize product is thickened, classified and dewatered in a multi-deck screen for the third time before being sent for thickening in a thickener.

In particular, classification of run-of-mine coal is carried out using the wet method.

In particular, before classification, run-of-mine coal is crushed.

In particular, before crushing, run-of-mine coal is subjected to preliminary classification.

In particular, the slurry pulp is fed from a slurry pulp storage tank or through pipelines (troughs) directly after the previous enrichment stage.

Brief description of the drawings

Fig. 1 shows a water-slurry scheme for thickening, dewatering and classifying coal slurry in a multi-deck screen obtained after wet classification of run-of-mine coal.

Fig. 2 shows a water-slurry scheme for thickening, dewatering and classification of coal slurry obtained after classification in a hydrocyclone.

Fig. 3 shows a water-slurry scheme for thickening, dewatering and classifying coal slurry obtained after thickening, dewatering and classifying coal slurry in a multi-deck screen.

Fig. 4 shows a water-slurry scheme for thickening, dewatering and classification of coal slurry obtained after classification in a hydrocyclone.

Fig. 5 shows a water-slurry diagram of the thickening, dewatering and classification of coal slurry obtained after thickening, dewatering and classification of coal slurry in a multi-deck screen.

Fig. 6 shows a water-slurry scheme for thickening, dewatering and classification of coal slurry obtained after double thickening, dewatering and classification of coal slurry in multi-deck screens.

Fig. 7 shows a water-slurry scheme for thickening, dewatering and classification of coal slurry obtained after triple thickening, dewatering and classification of coal slurry in multi-deck screens.

Implementation of the invention

The essence of the invention is that the sludge of anthracite, hard or brown coal in the form of pulp obtained during the classification of run-of-mine coal is thickened, classified and dewatered in multi-deck screens.

The supply of slurry pulp is carried out using a pumping apparatus from a sump (container, storage tank) or through gravity pipelines (troughs) from the equipment of the previous stage of classification or enrichment of coal at the enrichment plant.

Sludge is a collection of grains that become suspended with the flows of process water entering the processes of the water-sludge system.

Pulp is a mechanical mixture of water and coal.

Water-slurry scheme is a technological scheme for processing small grains of coal entering the processes with process water and regeneration of water for secondary enrichment.

Sump (accumulator) – a storage tank for sludge pulp for its accumulation before subsequent processing.

Multi-deck screens are high-frequency, low-amplitude screens for fine screening, which feature a vibration drive, polyurethane screens with a high cross-sectional area coefficient and rational use of the working surface of the screens due to optimal distribution of feed, which ensures high technological efficiency.

The screen combines high productivity and efficiency of the classification process with a relatively small footprint. The decks are mounted on one frame parallel to each other and have independent power supply. Screen panels are mounted on each deck. A repulping rubberized trough can be installed between the screen panels, in which the oversize product is pulped by sprayers directed into the trough. The screen is designed to obtain oversize and undersize products.

For thickening, dehydration and classification, the sludge pulp with sludge class, for example, up to 3.0 mm in grain of various sizes from the sludge pulp accumulator or through pipelines (troughs) is directly fed into a multi-deck screen (see Fig. 1).

The slurry pulp enters the accumulator after the wet classification stage of raw coal. Before wet classification, raw coal may be crushed. Before crushing, raw coal may be pre-classified.

Using a multi-deck screen, coal sludge is classified into an oversize product with sludge class, for example, 0.5-3.0 mm, and an undersize product with sludge class, for example, 0-0.5 mm.

The oversize product is fed for additional dehydration and/or enrichment. During additional dehydration, the solid (oversize product) and liquid (undersize product) components are separated.

During additional enrichment, coal concentrate and waste are separated from the pulp and sent separately for repeated dehydration, during which the coal concentrate is enriched.

The liquid component of the pulp is used to maintain the stability of the regenerative water system, i.e. it is reused to ensure the main coal enrichment processes.

The undersize product with sludge of class 0-0.5 mm is fed to the stages of thickening and/or enrichment and/or classification. At the thickening stage, the overflow and sediment are separated. At the enrichment stage, the concentrate and waste are separated. At the classification stage, sand and overflow are separated. Sand is sent for dewatering, and overflow is sent for enrichment and/or thickening.

In another embodiment, for thickening, dewatering and classifying, sludge pulp with sludge class, for example, up to 0.5 mm in grain of various sizes, obtained after classification in a hydrocyclone (see Fig. 2) or undersize product of thickening, dewatering and classification in a multi-deck screen of fraction class 0-3.0 mm (see Fig. 4) is fed into a multi-deck screen.

The slurry pulp enters the hydrocyclone from the slurry pulp accumulator after the stage of wet classification of raw coal or after thickening, dewatering and classification in a multi-deck screen or through pipelines (troughs) directly. Before dry or wet classification, raw coal can be crushed.

From the multi-deck screen, the concentrate (oversize product) is sent to a warehouse, and the liquid component (undersize product) is used to maintain the stability of the regenerative water system, i.e. it is reused to ensure the main coal enrichment processes.

In the third embodiment for thickening, dewatering and classifying, the sludge pulp obtained after classification in a hydrocyclone (see Fig. 3) or after thickening, dewatering and classifying in a multi-deck screen (see Fig. 5) with sludge class, for example, up to 3.0 mm in grain of various sizes for separating large grains before thickening in a thickener, in a radial or plate type, is first classified into oversize and undersize products, of which the undersize is sent for thickening, dewatering and classifying in a multi-deck screen.

A thickener is a device (structure) for thickening sludge and clarifying sludge water.

From the multi-deck screen, the oversize product is fed to the warehouse in the form of a concentrate, and the undersize product is transferred for thickening to the above-mentioned thickener for separating the overflow and sediment.

The described schemes of thickening, dewatering and classification of slurry pulp in multi-deck screens can be implemented in the technological scheme of coal enrichment separately (see Figs. 1, 2, 3), as well as in various combinations, for example, the first and second (see Fig. 4), the first and third (see Fig. 5), the second and third (see Fig. 6), as well as all together, that is, the first, second and third (see Fig. 7).

In 2024, tests were conducted at an operating coal preparation plant in Kuzbass to assess the classification efficiency (thickening, dewatering and classification) of sludge. The tests were conducted with classification by grain of different sizes on the same quality and volume of feedstock (coal pulp obtained after wet classification). The tests showed that the efficiency of existing process flow charts using classifying hydrocyclones was 85%, and the efficiency of using multi-deck screens in the various described implementation options was from 90 to 98.5%, which confirms the possibility of achieving the stated technical result.

The claimed invention has high technological efficiency due to the use of the same type of multi-deck screens in coal enrichment technology, the number of decks in each of which, depending on the yield of coal sludge from run-of-mine coal, can vary, as well as the number of multi-deck screens in the overall coal enrichment scheme.

Claims (5)

1. A method for classifying coal sludge, including classifying run-of-mine coal to obtain a sludge pulp sent for thickening, classification, dewatering and separation of coal concentrate, characterized in that the classification of the obtained sludge pulp is carried out on a multi-deck screen to obtain an oversize product with sludge of class 0.5-3.0 mm and an undersize product with sludge of class 0-0.5 mm, wherein the oversize product is fed for additional dewatering and/or enrichment, and the undersize product with sludge of class 0-0.5 mm is fed to the stages of thickening and/or enrichment and/or classification. 2. A method for classifying coal sludge, including classifying run-of-mine coal to obtain sludge pulp, classifying sludge pulp in a hydrocyclone with separation of overflow and sand, characterized in that the overflow from the hydrocyclone is classified into oversize and undersize products, while the undersize product, before being thickened in a thickener, is sent for classification in a multi-deck screen to obtain oversize and undersize products. 3. A method for classifying coal sludge, including classifying run-of-mine coal to obtain sludge pulp sent for thickening, classification, dewatering and separation of coal concentrate, characterized in that the classification of the obtained sludge pulp is carried out on a multi-deck screen to obtain an oversize product with sludge of class 0.5-3.0 mm and an undersize product with sludge of class 0-0.5 mm, wherein the oversize product is fed for dewatering and/or enrichment, and the undersize product with sludge of class 0-0.5 mm is fed for re-classification in a multi-deck screen to obtain oversize and undersize products. 4. A method for classifying coal sludge, including classifying run-of-mine coal to obtain sludge pulp, classifying sludge pulp in a hydrocyclone with separation of overflow and sand, from which coal concentrate is recovered, characterized in that the sand is sent for dehydration and/or enrichment, and to recover coal concentrate from the overflow, classification is carried out in a multi-deck screen to obtain oversize and undersize products, wherein the undersize product is sent for repeated classification in the multi-deck screen to obtain oversize and undersize products. 5. A method for classifying coal sludge, including classifying run-of-mine coal to obtain sludge pulp sent for thickening, classification, dewatering and separation of coal concentrate, characterized in that the sludge pulp is classified on a multi-deck screen to obtain an oversize product with sludge of class 0.5-3.0 mm and an undersize product with sludge of class 0-0.5 mm, wherein the oversize product is fed for additional dewatering and/or enrichment, and the undersize product with sludge of class 0-0.5 mm is fed for repeated classification in a multi-deck screen to obtain oversize and undersize products, wherein the undersize product is classified for the third time in a multi-deck screen to obtain oversize and undersize products before being sent for thickening in a thickener.