Method for combined ash reduction of high-ash anthracite by selection and smelting

Abstract

This invention discloses a method for combined ash reduction in the beneficiation and metallurgy of high-ash anthracite. Based on the dispersal characteristics of high-ash anthracite, a crushing-grinding-multi-stage flotation-alkali leaching process is designed, improving the flotation reagent regime. Simultaneously, a highly efficient combined collector is designed specifically for high-ash anthracite, enhancing the ash reduction effect of the process. Furthermore, this invention proposes an alkaline leaching treatment for the middlings obtained from flotation, improving the overall recovery rate of the coal preparation process. The low-ash anthracite product obtained by this method achieves a yield of over 56%, with ash content reduced to below 10%, and an overall recovery rate of over 84%, meeting the technical requirements for low-ash products. Moreover, this method requires only conventional mineral processing equipment, has a simple process flow, and is easily scalable for large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal separation and hydrometallurgy, and particularly relates to a method for combined separation and metallurgy of high-ash anthracite for ash reduction. BACKGROUND

[0002] Ash in coal is derived from minerals, which is the residue obtained after complete combustion of coal under certain conditions, and is a harmful substance. When the ash content of coal increases, its combustibility becomes poor, and the calorific value decreases. Ash in coal is also one of the pricing indicators. In calorific value pricing, ash content is an auxiliary indicator. When minerals burn and ash, they absorb heat, and a large amount of slag takes away heat, thereby reducing the calorific value of coal and affecting boiler operation (such as easy slagging and extinguishing), intensifying equipment wear and tear, and increasing the amount of slag. When coal is used for coking, the increase in ash content will also increase the ash content of coke, thereby reducing the utilization coefficient of blast furnaces. It must also be pointed out that the increase in ash content in coal increases the ineffective transportation and intensifies the tension of railway transportation in China. At the present stage, the main coal separation technology in China is gravity separation, that is, separation is carried out according to the physical property difference between coal and gangue, and the combined separation and metallurgy technology can realize efficient separation of coal and gangue and significantly reduce the ash content. Therefore, the combined separation and metallurgy treatment of high-ash anthracite can realize the effective utilization of high-ash coal that is difficult to handle by gravity separation, alleviate the energy shortage pressure, and has important economic significance.

[0003] The existing coal separation technology such as dense medium separation has high quality of raw coal during processing, and it is difficult to realize effective separation of high-ash coal. If only relying on flotation coal separation, it is also difficult to separate high-yield low-ash clean coal products, and there are problems such as poor selectivity of reagents. Fewer high-ash anthracites are treated by hydrometallurgy. Therefore, it is urgent to provide a method for efficient treatment and ash reduction of high-ash anthracite. SUMMARY

[0004] The purpose of the present application is to provide a method for combined separation and metallurgy of high-ash anthracite for ash reduction, which discards tailings with high ash content and realizes the separation and enrichment of low-ash anthracite.

[0005] The present application provides a method for combined separation and metallurgy of high-ash anthracite for ash reduction, comprising the following steps:

[0006] S1. crushing high-ash anthracite to a preset particle size to obtain a crushed product;

[0007] S2. grinding the crushed product obtained in step S1 to obtain a ground product;

[0008] S3. performing primary roughing on the ground product obtained in step S2 to obtain a roughing concentrate and a roughing tailing;

[0009] S4. The roughing tailings obtained in step S3 are subjected to cleaning flotation to obtain cleaning concentrate and cleaning tailings;

[0010] S5. The roughing concentrate obtained in step S3 and the cleaning concentrate obtained in step S4 are combined to perform first cleaning to obtain cleaning concentrate 1 and cleaning middlings 1;

[0011] S6. The cleaning concentrate 1 obtained in step S5 is subjected to second cleaning to obtain cleaning concentrate 2 and cleaning middlings 2;

[0012] S7. The cleaning concentrate 2 obtained in step S6 is subjected to third cleaning to obtain cleaning concentrate 3 and cleaning middlings 3;

[0013] S8. The cleaning concentrate 3 obtained in step S5 is subjected to fourth cleaning to obtain cleaning concentrate 4 and cleaning middlings 4;

[0014] S9. The cleaning middlings 2-4 obtained in steps S6-S8 are combined to perform alkali leaching to obtain leaching clean coal and leaching liquid;

[0015] S10. The cleaning concentrate 4 obtained in step S8 and the leaching clean coal obtained in step S9 are combined as clean coal products.

[0016] Further, in step S1, the high-ash anthracite is subjected to two-stage crushing, including coarse crushing and fine crushing, to obtain a crushing product with a particle size of 1-3 mm.

[0017] Further, in step S2, the grinding is wet ball grinding; the grinding aid is sodium carbonate, and the amount used is 500-800 g / t; the grinding concentration is 60%-70%, and the grinding time is 20-25 min.

[0018] Further, in step S3, in the roughing, the pulp concentration is 8-12%, the pH range of the roughing is 8-9; the dispersing agent used in the roughing is sodium carbonate, and the amount used is 1500-2500 g / t; the depressant used in the roughing is water glass, and the amount used is 2500-3500 g / t; the collector used in the roughing is a combination of kerosene or diesel oil and a high-efficiency combined collector, and the total amount of the collector used is 800-1200 g / t; the frother used in the roughing is methyl isobutyl carbinol, and the amount used is 300-500 g / t; the dosing sequence is pH adjusting agent, dispersing agent, depressant, collector, and frother, wherein each agent is dosed and stirred for 3-5 min, and the scraping time is 3-4 min.

[0019] The high-efficiency combined collector comprises coconut oil, palm oil, and methylnaphthalene in a ratio of (10-15):(3-5):(0.5-1.5).

[0020] Further, in step S4, the sweeping selection, the pulp concentration is 8-12%, the pH range of the sweeping selection is 8-9; the dispersing agent used in the sweeping selection is sodium carbonate, the usage amount is 500-1500 g / t; the inhibitor used in the sweeping selection is water glass, the usage amount is 1000-2000 g / t; the collector used in the sweeping selection is the combination of kerosene or diesel oil and high-efficiency combined collector, the total usage amount of the collector is 400-500 g / t; the frother used in the sweeping selection is methyl isobutyl carbinol, the usage amount is 200-300 g / t; the adding sequence of the reagents is dispersing agent, inhibitor, collector and frother, wherein each reagent is added and stirred for 3-5 minutes, and the scraping froth time is 3-4 minutes.

[0021] Further, in step S5, the first selection, the pulp concentration is 8-12%, the pH range of the first selection is 8-9; the dispersing agent used in the first selection is sodium carbonate, the usage amount is 500-1500 g / t; the inhibitor used in the first selection is water glass, the usage amount is 1000-2000 g / t; the collector used in the first selection is the combination of kerosene or diesel oil and high-efficiency combined collector, the total usage amount of the collector is 400-500 g / t; the frother used in the first selection is methyl isobutyl carbinol, the usage amount is 200-300 g / t; the adding sequence of the reagents is pH regulator, dispersing agent, inhibitor, collector and frother, wherein each reagent is added and stirred for 3-5 minutes, and the scraping froth time is 3-4 minutes.

[0022] Further, in steps S6-S8, the second-fourth selections, the pulp concentration is 8-12%, the pH range is 8-9, the dispersing agent is sodium carbonate, the usage amount is 500-1500 g / t, the inhibitor is water glass, the usage amount is 1000-2000 g / t; the adding sequence of the reagents is pH regulator, dispersing agent and inhibitor, wherein each reagent is added and stirred for 3-5 minutes, and the scraping froth time is 3-4 minutes.

[0023] Further, in step S9, the alkali leaching is pressure and temperature alkali leaching, the alkali used is 10-20% sodium hydroxide solution, the temperature is 160-180 DEG C, the pressure is 0.8-1 Mpa, the liquid-solid ratio is (3-3.5) : 1, and the time is 1-2 h.

[0024] Principle of the application:

[0025] (1) The application is based on the structural characteristics of anthracite, and the basic principle of crushing and grinding, the embedded particle size of coal and gangue minerals is fine, and the raw coal can only be crushed and ground for a long time to realize the dissociation of coal and gangue minerals, which improves the selective adsorption of subsequent flotation reagents, and fully grinding the coal is beneficial to the efficient alkali leaching;

[0026] (2) The present application utilizes the direct floatability difference between coal and ash, and effectively separates them through flotation. The synergistic effect of water glass and sodium carbonate realizes the dispersion of slime, greatly improves the absolute value of the negative potential of the mineral surface, and enhances the electrostatic repulsion force between the fine particles with the same charge, making them difficult to approach each other. The fatty acid collector has a strong selective collecting effect on coal, and kerosene or diesel oil is commonly used. When unsaturated fatty acid is mixed with it, a synergistic effect can occur. The degree of combination between bubbles and coal increases with the increase of unsaturation of fatty acid. The increase of unsaturated bond can increase the polarity of the collector molecule, promote its dispersion in the slurry, and increase the collision probability with the reagent. A small amount of methyl naphthalene can promote the adsorption between the reagent and coal. By compounding unsaturated fatty acid and methyl naphthalene in proportion, a better selective collecting effect can be obtained.

[0027] (3) The flotation roughing and scavenging in the method of the present application can remove the quartz components in raw coal which are easy to separate, and the removal rate of quartz components is high. No collector is added in the flotation cleaning except the first stage, which enhances the distinction between coal and mica, and produces low-ash flotation clean coal. The low-ash components are still present in the flotation middlings produced in the cleaning process. This part has a high yield and has not been effectively disposed of. Alkaline leaching can realize the leaching of silicon and aluminum components in this part of middlings. High temperature and high pressure provide the energy for reaction and leaching, and further promote the leaching process. Both the low-ash flotation clean coal and the low-ash leaching clean coal have high combustion values and meet the product standards of low-ash anthracite, so they can be combined.

[0028] Advantages of the present application:

[0029] (1) The present application utilizes the floatability difference between minerals, and can realize the separation of fine particles through flotation.

[0030] (2) The compounded unsaturated fatty acid collector used in the present application has high selective collecting effect, and enhances the separation between coal and gangue.

[0031] (3) The present application improves the clean coal yield and the recovery rate of raw coal through alkaline leaching of the concentrate in the cleaning process.

[0032] (4) The present application mixes the flotation clean coal and the leaching clean coal together, which improves the economic benefit.

[0033] (5) The process flow of the present application uses conventional mineral processing equipment, and the process flow is simple and easy to industrialize and mass produce. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The figure is a flowchart of the method of the present application. DETAILED DESCRIPTION

[0035] For the convenience of understanding the present application, the present application will be described more fully below with reference to the accompanying drawings and preferred embodiments of the application, but the scope of protection of the present application is not limited to the following specific embodiments.

[0036] Unless otherwise defined, all terms used in the description below have the same meaning as commonly understood by one of ordinary skill in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the scope of protection of the present application.

[0037] Example 1

[0038] The high-efficiency combined collector is configured, and the components and proportions of the high-efficiency combined collector are as follows: coconut oil: palm oil: methylnaphthalene = 10:3:0.5.

[0039] The present application provides a method for combined metallurgy and ash reduction of high-ash anthracite, and a flowchart thereof is shown in Figure 1 The method comprises the following steps:

[0040] Take 500g of high-ash anthracite with an ash content of 44.51%, and crush it in two stages to obtain a particle size of 1-3mm. Put the crushed high-ash anthracite into a conical ball mill for ball milling, with a pulp concentration of 70% and the addition of 500g / t of sodium carbonate as a grinding aid. Mill the ore for 25 minutes, filter and dry the pulp to obtain the milled product.

[0041] Take 100g of the milled product for rough flotation in a 1L XFG slot aeration flotation machine, adjust the pulp concentration to 10%, and use sodium carbonate to adjust the pH value to 9 throughout the process. The reagent system for rough flotation is as follows: sodium carbonate 2000g / t, water glass 3000g / t, kerosene 500g / t, high-efficiency combined collector 500g / t, and methyl isobutyl carbinol 500g / t. The order of adding reagents is pH adjuster, dispersant, depressant, collector, and frother, and each reagent is added and stirred for 3 minutes. The scraping froth time is 3 minutes to obtain rough concentrate and rough tailings.

[0042] Take the rough tailings for flotation scavenging, adjust the pulp concentration to 10%, and use sodium carbonate to adjust the pH value to 9 throughout the process. The reagent system for flotation scavenging is as follows: sodium carbonate 1000g / t, water glass 1500g / t, kerosene 250g / t, high-efficiency combined collector 250g / t, and methyl isobutyl carbinol 250g / t. The order of adding reagents is dispersant, depressant, collector, and frother, and each reagent is added and stirred for 3 minutes. The scraping froth time is 3 minutes to obtain scavenging concentrate and scavenging tailings.

[0043] The sweep concentrate and the roughing concentrate are combined to carry out one-stage cleaning, the pulp concentration is adjusted to 10%, sodium carbonate is used to adjust the pH value to 9 in the whole process, the reagent system of the one-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t, kerosene 250 g / t, high-efficiency combined collector 250 g / t, and methyl isobutyl carbinol 250 g / t; the dosing sequence is pH adjusting agent, dispersant, depressant, collector and frother, each reagent is dosed and stirred for 3 minutes, the froth scraping time is 3 minutes, and the cleaned concentrate 1 and the cleaning middlings 1 are obtained.

[0044] The cleaned concentrate 1 is taken to carry out two-stage cleaning, the pulp concentration is adjusted to 10%, sodium carbonate is used to adjust the pH value to 9 in the whole process, the reagent system of the two-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t, and the cleaned concentrate 2 and the cleaning middlings 2 are obtained; the dosing sequence is pH adjusting agent, dispersant and depressant, each reagent is dosed and stirred for 3 minutes, and the froth scraping time is 3 minutes.

[0045] The cleaned concentrate 2 is taken to carry out three-stage cleaning, the pulp concentration is adjusted to 10%, sodium carbonate is used to adjust the pH value to 9 in the whole process, the reagent system of the three-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t, and the cleaned concentrate 3 and the cleaning middlings 3 are obtained; the dosing sequence is pH adjusting agent, dispersant and depressant, each reagent is dosed and stirred for 3 minutes, and the froth scraping time is 3 minutes.

[0046] The cleaned concentrate 3 is taken to carry out four-stage cleaning, the pulp concentration is adjusted to 10%, sodium carbonate is used to adjust the pH value to 9 in the whole process, the reagent system of the four-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t, and the cleaned concentrate 4 and the cleaning middlings 4 are obtained; the dosing sequence is pH adjusting agent, dispersant and depressant, each reagent is dosed and stirred for 3 minutes, and the froth scraping time is 3 minutes.

[0047] The cleaning middlings 2-4 and the cleaning middlings are combined to carry out alkali leaching, the process conditions of the alkali leaching are that the cleaning middlings are added into 10% sodium hydroxide solution, the liquid-solid ratio is 3.5:1, the temperature is 170 ℃, the pressure is 1 Mpa, and the time is 1 hour, and the leached clean coal and the leaching solution are obtained.

[0048] The leached clean coal and the cleaned concentrate 4 are combined to be the final low-ash anthracite product. The yield of the obtained low-ash anthracite product is 56.98%, the ash content is 9.78%, the recovery rate is 92.64%, and the low-ash product meets the technical requirements.

[0049] Example 2

[0050] The high-efficiency combined collector is configured, and the components and proportions of the high-efficiency combined collector are: coconut oil: palm oil: methyl naphthalene = 15:5:1.5.

[0051] Take 500 g of high-ash anthracite with ash content of 44.51%, crush in two stages, and the particle size after crushing is 1-3 mm. Put the crushed high-ash anthracite into a conical ball mill for ball milling, the pulp concentration is 60%, add 800 g / t of sodium carbonate as grinding aid, and grind for 20 min. Filter and dry the pulp to obtain the ground product.

[0052] Take 100 g of the ground product for rough flotation in a 1 L XFG hanging slot aeration flotation machine, adjust the pulp concentration to 12%, use sodium carbonate to adjust the pH value to 8 throughout the process, and the reagent system for rough flotation is: sodium carbonate 2000 g / t, water glass 3000 g / t, kerosene 500 g / t, high-efficiency combined collector 500 g / t, and methyl isobutyl carbinol 500 g / t. The dosing sequence is pH adjusting agent, dispersant, depressant, collector, and frother, and each reagent is dosed and stirred for 5 min. The scraping froth time is 4 min to obtain rough concentrate and rough tailings.

[0053] Take the rough tailings for flotation scavenging, adjust the pulp concentration to 12%, use sodium carbonate to adjust the pH value to 8 throughout the process, and the reagent system for flotation scavenging is: sodium carbonate 1000 g / t, water glass 1500 g / t, kerosene 250 g / t, high-efficiency combined collector 250 g / t, and methyl isobutyl carbinol 250 g / t. The dosing sequence is dispersant, depressant, collector, and frother, and each reagent is dosed and stirred for 5 min. The scraping froth time is 4 min to obtain scavenging concentrate and scavenging tailings.

[0054] Combine the scavenging concentrate and the rough concentrate for one-stage cleaning, adjust the pulp concentration to 12%, use sodium carbonate to adjust the pH value to 8 throughout the process, and the reagent system for one-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t, kerosene 250 g / t, high-efficiency combined collector 250 g / t, and methyl isobutyl carbinol 250 g / t. The dosing sequence is pH adjusting agent, dispersant, depressant, collector, and frother, and each reagent is dosed and stirred for 5 min. The scraping froth time is 4 min to obtain cleaning concentrate 1 and cleaning middlings 1.

[0055] Take the cleaning concentrate 1 for two-stage cleaning, adjust the pulp concentration to 12%, use sodium carbonate to adjust the pH value to 8 throughout the process, and the reagent system for two-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t. The dosing sequence is pH adjusting agent, dispersant, and depressant, and each reagent is dosed and stirred for 5 min. The scraping froth time is 4 min to obtain cleaning concentrate 2 and cleaning middlings 2.

[0056] The selected concentrate 2 is subjected to three-stage cleaning, the pulp concentration is adjusted to 12%, sodium carbonate is used to adjust the pH value to 8, the reagent system of three-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t; the dosing sequence is pH adjusting agent, dispersant, depressant, wherein each reagent is dosed and stirred for 5 minutes, the froth scraping time is 4 minutes, to obtain the cleaned concentrate 3 and the cleaned middlings 3.

[0057] The cleaned concentrate 3 is subjected to four-stage cleaning, the pulp concentration is adjusted to 12%, sodium carbonate is used to adjust the pH value to 8, the reagent system of four-stage cleaning is: sodium carbonate 2000 g / t, water glass 3000 g / t; the dosing sequence is pH adjusting agent, dispersant, depressant, wherein each reagent is dosed and stirred for 5 minutes, the froth scraping time is 4 minutes, to obtain the cleaned concentrate 4 and the cleaned middlings 4.

[0058] The cleaned middlings 2-4 are combined and subjected to alkali leaching, the process conditions of alkali leaching are: the cleaned middlings are added into 20% sodium hydroxide solution, the liquid-solid ratio is 3:1, the temperature is 170°C, the pressure is 0.8 Mpa, and the time is 1 hour, to obtain the leached clean coal and the leaching solution.

[0059] The leached clean coal and the cleaned concentrate 4 are combined to obtain the final low-ash anthracite product. The yield of the obtained low-ash anthracite product is 52.22%, the ash content is 9.91%, and the recovery rate is 84.78%, which meets the technical requirements of low-ash products.

[0060] Comparative Example 1

[0061] Compared with Example 1, only the high-efficiency combined collector in the roughing, scavenging and one-stage cleaning is replaced by an equal amount of kerosene, and the remaining steps remain unchanged. The yield of the final low-ash anthracite product is 50.71%, the ash content is 12.11%, and the recovery rate is 80.32%, which does not meet the technical requirements of low-ash products.

[0062] Comparative Example 2

[0063] Compared with Example 1, only the grinding time of the ball milling step is replaced by 18 min, and the remaining steps remain unchanged. The yield of the final low-ash anthracite product is 44.50%, the ash content is 12.71%, and the recovery rate is 70.00%, which does not meet the technical requirements of low-ash products.

[0064] Comparative Example 3

[0065] Compared with Example 1, only the alkali leaching part is replaced by acid leaching, the process conditions of the acid leaching are that the cleaned middlings are added into 10% hydrochloric acid + 1% hydrofluoric acid, the liquid-solid ratio is 5:1, the acid leaching temperature is 90 degrees, the time is 2 hours, and other steps are unchanged. The final low-ash anthracite product yield is 57.80%, the ash content is 17.41%, and the recovery rate is 86.03%. The ash content is too high and does not meet the technical requirements of low-ash products.

[0066] Comparative Example 4

[0067] Compared with Example 1, only the reaction temperature of alkali leaching is adjusted to 130 DEG C, and other steps are unchanged. The final low-ash anthracite product yield is 57.63%, the ash content is 10.59%, and the recovery rate is 92.86%. It does not meet the technical requirements of low-ash products.

Claims

1. A method for combined beneficiation and ash reduction of high-ash anthracite, characterized in that, The method comprises the following steps: S1. crushing high-ash anthracite to a preset particle size to obtain a crushed product; S2. grinding the crushed product obtained in step S1 to obtain a ground product; S3. performing primary roughing on the ground product obtained in step S2 to obtain a roughing concentrate and a roughing tailing; S4. performing a flotation scavenging on the roughing tailing obtained in step S3 to obtain a scavenging concentrate and a scavenging tailing; S5. combining the roughing concentrate obtained in step S3 and the scavenging concentrate obtained in step S4 to perform a first cleaning to obtain a cleaning concentrate 1 and a cleaning middling 1; S6. performing a second cleaning on the cleaning concentrate 1 obtained in step S5 to obtain a cleaning concentrate 2 and a cleaning middling 2; S7. performing a third cleaning on the cleaning concentrate 2 obtained in step S6 to obtain a cleaning concentrate 3 and a cleaning middling 3; S8. performing a fourth cleaning on the cleaning concentrate 3 obtained in step S5 to obtain a cleaning concentrate 4 and a cleaning middling 4; S9. combining the cleaning middlings 2-4 obtained in steps S6-S8 to perform an alkali leaching to obtain a leaching clean coal and a leaching liquid; S10. combining the cleaning concentrate 4 obtained in step S8 and the leaching clean coal obtained in step S9 as a clean coal product; The collector used in the roughing is a combination of kerosene or diesel oil and a high-efficiency combined collector, and the total amount of the collector is 800-1200 g / t; The collector used in the scavenging is a combination of kerosene or diesel oil and a high-efficiency combined collector, and the total amount of the collector is 400-500 g / t; The collector used in the first cleaning is a combination of kerosene or diesel oil and a high-efficiency combined collector, and the total amount of the collector is 400-500 g / t; The components and proportions of the high-efficiency combined collector are as follows: coconut oil: palm oil: methylnaphthalene = (10-15): (3-5): (0.5-1.5).

2. The method for combined metallurgy and ash reduction of high-ash anthracite according to claim 1, characterized in that, In step S1, the high-ash anthracite is crushed in two stages, including coarse crushing and fine crushing, and the particle size of the crushed product is 1-3 mm.

3. The method for combined metallurgy and ash reduction of high-ash anthracite according to claim 1, characterized in that, In step S2, the grinding is wet ball grinding; the grinding aid is sodium carbonate, and the amount used is 500-800 g / t; the grinding concentration is 60%-70%, and the grinding time is 20-25 min.

4. The method for combined metallurgy and ash reduction of high-ash anthracite according to claim 1, characterized in that, In step S3, in the roughing, the pulp concentration is 8-12%, the pH range of the roughing is 8-9; the dispersing agent used in the roughing is sodium carbonate, and the amount used is 1500-2500 g / t; the depressant used in the roughing is water glass, and the amount used is 2500-3500 g / t; the frother used in the roughing is methyl isobutyl carbinol, and the amount used is 300-500 g / t; the dosing sequence is a pH adjusting agent, a dispersing agent, a depressant, a collector, and a frother, wherein each type of agent is dosed and stirred for 3-5 min, and the scraping time is 3-4 min.

5. The method for combined metallurgy and ash reduction of high-ash anthracite according to claim 1, characterized in that, In step S4, the sweeping selection, the pulp concentration is 8-12%, the pH range of the sweeping selection is 8-9; the dispersing agent used in the sweeping selection is sodium carbonate, the usage amount is 500-1500 g / t; the inhibitor used in the sweeping selection is water glass, the usage amount is 1000-2000 g / t; the foaming agent used in the sweeping selection is methyl isobutyl carbinol, the usage amount is 200-300 g / t; the dosing sequence is dispersing agent, inhibitor, collector, foaming agent, wherein each kind of agent is dosed and stirred for 3-5 minutes, and the skimming time is 3-4 minutes.

6. The method for combined metallurgy and ash reduction of high-ash anthracite according to claim 1, characterized in that, In step S5, the first selection, the pulp concentration is 8-12%, the pH range of the first selection is 8-9; the dispersing agent used in the first selection is sodium carbonate, the usage amount is 500-1500 g / t; the inhibitor used in the first selection is water glass, the usage amount is 1000-2000 g / t; the foaming agent used in the first selection is methyl isobutyl carbinol, the usage amount is 200-300 g / t; the dosing sequence is pH adjusting agent, dispersing agent, inhibitor, collector, foaming agent, wherein each kind of agent is dosed and stirred for 3-5 minutes, and the skimming time is 3-4 minutes.

7. The method for combined metallurgy and ash reduction of high-ash anthracite according to claim 1, characterized in that, In steps S6-S8, the second-fourth selection, the pulp concentration is 8-12%, the pH range is 8-9, the dispersing agent is sodium carbonate, the usage amount is 500-1500 g / t, the inhibitor is water glass, the usage amount is 1000-2000 g / t; the dosing sequence is pH adjusting agent, dispersing agent, inhibitor, wherein each kind of agent is dosed and stirred for 3-5 minutes, and the skimming time is 3-4 minutes.

8. The method for combined metallurgy and ash reduction of high-ash anthracite according to claim 1, characterized in that, In step S9, the alkali leaching is pressure and temperature alkali leaching, the alkali used is 10-20% sodium hydroxide solution, the temperature is 160-180℃, the pressure is 0.8-1 Mpa, the liquid-solid ratio is (3-3.5):1, and the time is 1-2 h.

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