Coal dressing process and method for activation, quality improvement and ash reduction of low-quality coal mine

Abstract

The invention discloses a coal dressing process and method for activation, quality improvement and ash reduction of a low-quality coal mine. The invention provides an integrated process of an ore grinding-flotation-heating activation-concentration closed-circuit scheme on the basis of the fine dissemination characteristic and surface chemical characteristics of high-ash anthracite. And meanwhile, an optimized flotation reagent system is adopted, an efficient combined collecting agent composed of vegetable oil and coconut oil amine is designed, and the selective adsorption efficiency of coal particles is remarkably improved. Aiming at flotation coarse coal, the silicate mineral structure is damaged through heating activation of sodium hydroxide, and deep removal of ash is realized by combining washing and closed-loop flotation concentration processes. The yield of the obtained low-ash anthracite product reaches 60% or above, the ash content is reduced to 10% or below, and the resource utilization rate is effectively increased through the middling coal closed loop design. All process steps adopt conventional preparation equipment, the flow is simple, the cost is controllable, and the method is suitable for industrial large-scale application.

Description

Technical Field

[0001] The present invention belongs to the technical fields of coal separation and hydrometallurgy, and particularly relates to a coal preparation process and method for activating, upgrading and reducing ash of low-quality coal mines. Background Art

[0002] The ash in coal is mainly composed of minerals and is the incombustible residue after coal combustion, which has a significant negative impact on coal quality and utilization efficiency. High ash content not only leads to a decrease in coal calorific value, easy slagging during combustion and increased equipment wear, but also increases the ash content in coke in the coking process, thereby affecting the production efficiency of blast furnaces. In addition, high-ash coal generates a large amount of ineffective load during transportation and utilization, further exacerbating energy waste and transportation pressure. Traditional coal preparation technologies mainly rely on gravity separation, which depends on the density difference between coal and gangue to achieve separation, but has limited treatment effects on high-ash coal (especially anthracite), and it is difficult to effectively dissociate the intergrowth of fine disseminated minerals and organic matter, resulting in high ash content in clean coal and making it difficult to be widely applied to the upgrading of low-value coal resources.

[0003] Existing separation technologies such as dense medium coal preparation have high requirements for raw coal quality and are difficult to adapt to the complex mineral composition of high-ash coal; although conventional flotation processes can achieve partial separation through reagent adsorption, they are limited by problems such as small differences in coal surface hydrophobicity and insufficient reagent selectivity, resulting in low clean coal yield and large fluctuations in ash content. In addition, although hydrometallurgy technology can achieve deep ash removal, it has defects such as high energy consumption and difficult wastewater treatment, and it is difficult to balance economy and environmental protection. In view of the above problems, there is an urgent need to develop an efficient and low-cost coal preparation process to achieve deep ash removal and quality improvement of low-quality high-ash coal through physical-chemical synergistic effects, while ensuring the industrial feasibility of the process. Summary of the Invention

[0004] The purpose of the present invention is to provide a coal preparation process and method for activating, upgrading and reducing ash of low-quality coal mines, which uses an integrated process of crushing-grinding-rougher flotation-heating activation-cleaner flotation to treat high-ash low-quality anthracite, improve flotation selectivity, and achieve high recovery rates of valuable components in high-ash low-quality anthracite.

[0005] To achieve the above purpose, the following is the technical solution of the present invention:

[0006] The present invention provides a coal preparation process and method for activating, upgrading and reducing ash of low-quality coal mines, including the following steps:

[0007] S1. Crushing and screening high-ash low-quality anthracite to obtain crushed products;

[0008] S2. Conducting two-stage one-closed-circuit grinding on the crushed products to obtain ground products;

[0009] S3. Conduct rough flotation and scavenging on the ball-milled product to obtain rough flotation concentrate;

[0010] S4. Wash the rough flotation concentrate, then conduct heating activation, and filter and dehydrate to obtain activated clean coal;

[0011] S5. Conduct selective flotation on the activated clean coal to obtain clean coal products.

[0012] Further, in step S1, the high-ash and low-quality anthracite is crushed in three stages, including coarse crushing, medium crushing, and fine crushing. The particle size of the crushed product obtained by screening is less than 3 mm, and the particles with a particle size greater than 3 mm are returned to the fine crushing step.

[0013] Further, in step S2, the two-stage one-closed-circuit grinding is coarse grinding and fine grinding; the grinding is wet ball grinding; the grinding aid is sodium carbonate or sodium hexametaphosphate, and the dosage is 400 - 600 g / t; the grinding medium is steel balls or ceramic balls, the grinding concentration is 60% - 70%, and it is ground to a proportion of -0.074 mm accounting for 90 - 95% and -0.044 mm accounting for 70 - 75%.

[0014] Further, in step S3, the milled product is subjected to rough flotation to obtain rough flotation concentrate and rough flotation tailings; the rough flotation tailings are further subjected to scavenging to obtain scavenging concentrate and scavenging tailings; the scavenging tailings are treated as tailings, and the scavenging concentrate and the rough flotation concentrate are combined as the rough flotation concentrate.

[0015] Further, in step S3, in the rough flotation, the pulp concentration is 8 - 12%, the pH range of the rough flotation is 8 - 9, and the pH regulator is sodium carbonate; the dispersant used in the rough flotation is sodium carbonate or sodium hexametaphosphate, and the dosage is 1500 - 2500 g / t; the inhibitor used in the rough flotation is sodium fluorosilicate or sodium silicate, and the dosage is 2500 - 3500 g / t; the collector used in the rough flotation is a combination of diesel oil and a high-efficiency combined collector, and the total dosage of the collector is 800 - 1200 g / t; the frother used in the rough flotation is methyl isobutyl carbinol, and the dosage is 300 - 500 g / t; the dosing sequence is pH regulator, dispersant, inhibitor, collector, frother, and each reagent is dosed and stirred for 3 - 5 minutes, and the foam scraping time is 3 - 4 minutes;

[0016] The composition and proportion of the high-efficiency combined collector are: vegetable oil: emulsifier = (98 - 99): (1 - 2), where the vegetable oil is coconut oil or peanut oil or cottonseed oil, and the emulsifier is coconut amine.

[0017] Further, in step S3, during the scavenging, the pulp concentration is 8-12%, and the pH range for scavenging is 8-9; the dispersant used for scavenging is sodium carbonate or sodium hexametaphosphate, and the dosage is 500-1500 g / t; the inhibitor used for scavenging is sodium fluorosilicate or sodium silicate, and the dosage is 1000-2000 g / t; the collector used for scavenging is a combination of diesel oil and a high-efficiency combined collector, and the total dosage of the collector is 200-300 g / t; the frother used for scavenging is methyl isobutyl carbinol, and the dosage is 200-300 g / t; the dosing sequence is dispersant, inhibitor, collector, frother, and for each chemical, the dosing and stirring time is 3-5 minutes, and the foam scraping time is 3-4 minutes.

[0018] Further, in step S4, during the washing, the pulp concentration is 8-12%, the detergent is 70-80% ethanol, the washing temperature is normal temperature, the washing time is 5-30 minutes, mechanical stirring is adopted, and the stirring speed is 200-300 rpm.

[0019] Further, in step S4, during the heating and activation, the activator is sodium hydroxide, the dosage is 8-12%, the liquid-solid ratio is controlled at (2-4):1, the heating temperature is 100-150 °C, and the heating and activation duration is 1-2 h.

[0020] Further, in step S5, the flotation cleaning includes cleaning 1 and cleaning 2; both cleaning 1 and cleaning 2 adjust the pulp concentration to 8-12% and the pH range to 8-9;

[0021] For cleaning 1, the dispersant is sodium carbonate or sodium hexametaphosphate, and the dosage of the dispersant is 1500-3000 g / t; the inhibitor is sodium fluorosilicate or sodium silicate, and the dosage of the inhibitor is 2500-3500 g / t; the collector is a combination of diesel oil and a high-efficiency combined collector, and the total dosage of the collector is 75-125 g / t; the frother is methyl isobutyl carbinol, and the dosage of the frother is 75-125 g / t; cleaned clean coal 1 and cleaned middlings 1 are obtained, and cleaned clean coal 1 is subjected to cleaning 2;

[0022] For cleaning 2, the dispersant is sodium carbonate or sodium hexametaphosphate, and the dosage of the dispersant is 1500-3000 g / t; the inhibitor is sodium fluorosilicate or sodium silicate, and the dosage of the inhibitor is 2500-3500 g / t; cleaned clean coal 2 and flotation middlings 2 are obtained, and flotation middlings 2 are returned to cleaning 1 for re-selection; cleaned clean coal 2 is used as the clean coal product.

[0023] The principle of the present invention:

[0024] (1) According to the analysis of the physical structure characteristics of anthracite and its crushing and grinding mechanism, there is a fine-grained dissemination form between the coal quality and the associated gangue minerals. It is necessary to carry out a long-time crushing treatment to fully dissociate the coal matrix from the symbiotic gangue minerals. This deep dissociation process can not only optimize the selective adsorption efficiency of the agent on the target components in the subsequent flotation process, but also create more favorable conditions for the subsequent heating activation by fully refining the coal materials;

[0025] (2) Mineralogical analysis shows that the ash of coal quality is mainly composed of silicate minerals (quartz, mica) and is accompanied by a small amount of sulfide minerals (such as pyrite). From the perspective of interfacial chemistry, the coal matrix has natural hydrophobic characteristics and shows good surface floatability in the flotation system; while silicate minerals such as quartz have significantly limited floating activity due to their strong hydrophilic surface characteristics. Based on this surface wettability difference mechanism, the flotation process can achieve the efficient separation of hydrophobic coal particles and hydrophilic gangue minerals through the selective adhesion of minerals and bubbles;

[0026] (3) The synergistic use of sodium hexametaphosphate or sodium carbonate, sodium silicate or sodium fluorosilicate, based on the double-layer regulation theory, this technology strengthens the surface charge characteristics of mineral particles, significantly increases the negative value of the zeta potential of the slime system, and thus forms a high-intensity interlayer interaction of like charges between fine-grained minerals. This charge regulation mechanism significantly improves the colloidal stability and effectively inhibits the agglomeration tendency of fine particles by establishing a high-energy electrostatic potential barrier;

[0027] (4) Based on the interfacial chemistry theory, vegetable oil collectors show significant selective adsorption characteristics in the coal flotation process. The number of unsaturated double bonds in the molecular structure of the vegetable oil collector system is positively correlated with the stability of the coal particle-bubble complex. Research shows that when a specific composition of vegetable oil forms a composite agent with unsaturated fatty acid esters, it can produce synergistic effects through π-π conjugation. This molecular configuration can not only enhance the directional arrangement of the polar groups of the agent, but also improve the dispersion degree of the agent molecules in the pulp system through micellization, thereby significantly increasing the probability of effective adsorption collision. Adding an appropriate amount of coconut oil amine as an auxiliary collector can strengthen the chemical adsorption strength of the agent on the coal surface through the coordination of amino groups. By constructing a vegetable oil-coconut oil amine composite agent system, the synchronization optimization of flotation selectivity and recovery rate can be achieved;

[0028] (5) The core principle of sodium hydroxide heating activation is that under high-temperature conditions, sodium hydroxide undergoes chemical etching with minerals such as quartz and clay in coal, destroys the lattice structures of silicon-oxygen tetrahedrons and aluminum-oxygen octahedrons, generates soluble sodium silicate, sodium aluminate and metal hydroxy complexes, exposes and dissolves the encapsulated ash in the liquid phase, and significantly reduces the ash content after subsequent washing and filtration, ultimately achieving the goal of coal quality purification.

[0029] The beneficial effects of the present invention:

[0030] The present invention first constructs a multi-stage flotation system through interfacial chemistry regulation, and realizes the efficient separation of fine particles by utilizing the difference in the wettability of mineral surfaces. Then, a composite collector is used to strengthen the selective adsorption of coal particles, and the combined process of roughing-scavenging is combined to remove gangue minerals in advance. Finally, through the activation and heating of the activator, and in cooperation with the closed-circuit circulation system of middlings, the resource utilization rate is improved. The entire process is modularly combined based on conventional beneficiation equipment, and industrial production is achieved by regulating process parameters, combining separation efficiency and engineering feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a process flow schematic diagram of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] For the convenience of understanding the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings of the specification and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0033] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

[0034] Example 1

[0035] Configure an efficient combined collector. The components and proportions of the efficient combined collector are: 80% coconut oil, 19% peanut oil, and 1% coconut amine.

[0036] The present invention provides a coal preparation process and method for activating, upgrading and reducing ash of low-quality coal mines. The process flow schematic diagram is as Figure 1 shown, including the following steps:

[0037] Take 500 g of high-ash anthracite with an ash content of 44.51%, crush it in three stages and screen it. The particle size of the crushed product is less than 3 mm;

[0038] Add the crushed product to a conical ball mill for grinding. The pulp concentration is 70%, add 600 g / t of sodium carbonate as a grinding aid, grind for 30 minutes, filter and dry the pulp to obtain a grinding product.

[0039] 100 g of the ground product was subjected to rough flotation in a 1-L XFG hanging-cell pneumatic flotation machine. The pulp concentration was adjusted to 10%, and the pH was adjusted to 9 with sodium carbonate throughout the process. The reagent regime for rough flotation was 2000 g / t of sodium carbonate, 3000 g / t of sodium silicate, 500 g / t of diesel, 500 g / t of a high-efficiency combined collector, and 500 g / t of methyl isobutyl carbinol; the rough concentrate and the rough tailings were obtained. The rough tailings were subjected to scavenging flotation. The reagent regime for scavenging flotation was 1000 g / t of sodium carbonate, 1500 g / t of sodium silicate, 250 g / t of diesel, 250 g / t of a high-efficiency combined collector, and 250 g / t of methyl isobutyl carbinol. After foaming, the scraping time for each group was controlled at 3 min to obtain the scavenging concentrate and the scavenging tailings; the scavenging concentrate was combined with the rough concentrate as the flotation concentrate.

[0040] The flotation concentrate was washed. In a stirring tank, the pulp concentration was adjusted to 10%, the detergent was 70% ethanol, the washing temperature was normal temperature, and the washing time was 30 minutes. Mechanical stirring was used, and the stirring speed was 250 rpm to obtain the washed product. The washed product was subjected to heating activation. The conditions for heating activation were a 10% sodium hydroxide solution, a liquid-to-solid ratio of 3:1, a temperature of 150 °C, and a time of one hour to obtain the activated clean coal.

[0041] The activated clean coal was subjected to cleaning flotation in a 500-ml XFG hanging-cell pneumatic flotation machine; the cleaning flotation included cleaning 1 and cleaning 2; the reagent regime for cleaning 1 was 2000 g / t of sodium carbonate, 3000 g / t of sodium silicate, 100 g / t of diesel, 100 g / t of a high-efficiency combined collector, and 100 g / t of methyl isobutyl carbinol. After aeration, the foam was scraped for 3 min, and the foam product was transferred to a 500-ml XFG hanging-cell pneumatic flotation machine for cleaning 2. The reagent regime for cleaning 2 was 2000 g / t of sodium carbonate and 3000 g / t of sodium silicate to obtain the clean coal product, and the middlings from the second-stage flotation were returned to the first-stage cleaning for re-selection. The yield of the obtained low-ash anthracite product was 60.18%, and the ash content was 9.69%, meeting the technical requirements of the low-ash product.

[0042] Example 2

[0043] A high-efficiency combined collector was prepared. The components and proportions of the high-efficiency combined collector were: 80% coconut oil, 19% peanut oil, and 1% coconut amine.

[0044] The present invention provides a coal preparation process and method for activating, upgrading, and reducing the ash content of low-quality coal mines. The flow schematic diagram is as Figure 1 shown and includes the following steps:

[0045] 500 g of high-ash anthracite with an ash content of 44.51% was crushed in three stages and screened, and the particle size of the obtained crushed product was less than 3 mm;

[0046] The crushed product is added to a conical ball mill for grinding. The pulp concentration is 70%, 600 g / t of sodium carbonate is added as a grinding aid, and grinding is carried out for 30 minutes. The pulp is filtered and dried to obtain the ground product.

[0047] 100 g of the ground product is taken for rough flotation in a 1 L XFG flotation cell with air inflation. The pulp concentration is adjusted to 10%, and the pH is adjusted to 9 with sodium carbonate throughout the process. The reagent regime for rough flotation is 2000 g / t of sodium carbonate, 3000 g / t of sodium silicate, 400 g / t of diesel, 400 g / t of a high-efficiency combined collector, and 400 g / t of methyl isobutyl carbinol; the rough concentrate and the rough tailings are obtained; the rough tailings are taken for scavenger flotation. The reagent regime for scavenger flotation is 1000 g / t of sodium carbonate, 1500 g / t of sodium silicate, 200 g / t of diesel, 200 g / t of a high-efficiency combined collector, and 200 g / t of methyl isobutyl carbinol. After foaming, the scraping time for each group is controlled at 3 min to obtain the scavenger concentrate and the scavenger tailings; the scavenger concentrate and the rough concentrate are combined as the flotation concentrate.

[0048] The flotation concentrate is taken for washing. In a stirring tank, the pulp concentration is adjusted to 10%, the detergent is 70% ethanol, the washing temperature is normal temperature, and the washing time is 30 minutes. Mechanical stirring is used, and the stirring speed is 250 rpm to obtain the washed product. The washed product is taken for heating activation. The heating activation conditions are a 10% sodium hydroxide solution, a liquid-solid ratio of 3:1, a temperature of 150 °C, and a time of one hour to obtain the activated clean coal.

[0049] The activated clean coal is taken for cleaning flotation in a 500 ml XFG flotation cell with air inflation; the cleaning flotation includes cleaning 1 and cleaning 2; the reagent regime for cleaning 1 is 2000 g / t of sodium carbonate, 3000 g / t of sodium silicate, 100 g / t of diesel, 100 g / t of a high-efficiency combined collector, and 100 g / t of methyl isobutyl carbinol. After air inflation, the foam is scraped for 3 min, and the foam product is transferred to a 500 ml XFG flotation cell for cleaning 2. The reagent regime for cleaning 2 is 2000 g / t of sodium carbonate and 3000 g / t of sodium silicate to obtain the clean coal product, and the middlings from the second-stage flotation are returned to the first-stage cleaning for re-selection. The yield of the obtained low-ash anthracite product is 54.29%, and the ash content is 9.41%, meeting the technical requirements of low-ash products.

[0050] Comparative Example 1

[0051] Compared with Example 1, except that the high-efficiency combined collector is replaced with an equal amount of diesel, the remaining steps are exactly the same as in Example 1, that is, only kerosene is used as the collector, and the total amount of collector used remains unchanged. The yield of the obtained low-ash anthracite product is 62.01%, and the ash content is 13.16%, not meeting the technical requirements of low-ash products.

[0052] Comparative Example 2

[0053] Compared with Example 1, except that the grinding time was replaced with 20 min, the remaining steps were exactly the same as those in Example 1. The yield of the low-ash anthracite product obtained was 40.10%, the ash content was 9.51%, and the valuable components and gangue components were not fully dissociated. Although it met the technical requirements of the low-ash product, the yield decreased significantly, and the advantages involved in the patent were not brought into play.

[0054] Comparative Example 3

[0055] Compared with Example 1, except that diesel was replaced with an equal amount of high-efficiency combined collector, the remaining steps were exactly the same as those in Example 1, that is, only the high-efficiency combined collector was used as the collector, and the total amount of collector used remained unchanged. The foaming effect was poor, the yield was low, and there was no value in the flotation test.

[0056] Comparative Example 4

[0057] Compared with Example 1, except that the heating activation temperature was adjusted to 130 °C, the remaining steps were exactly the same as those in Example 1. The yield of the low-ash anthracite product obtained was 58.11%, and the ash content was 11.59%, which did not meet the technical requirements of the low-ash product.

[0058] From the results of the above examples and comparative examples, it can be seen that based on the improved reagent system for flotation, the present invention adopts a technical scheme of combined beneficiation and smelting to synergistically reduce ash, overcomes the disadvantages of low recovery rate and low refinement degree in the existing coal preparation technology, and realizes efficient separation of coal preparation for ash reduction.

[0059] The above examples are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope of the present invention, according to the technical solution and its concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A coal preparation process and method for activating low-quality coal mines to improve quality and reduce ash, characterized in that: The following steps are involved: S1. crushing and sieving high-ash low-quality anthracite to obtain a crushed product; S2. The crushed product is subjected to two-stage and one-closed-circuit grinding to obtain a grinding product; S3. flotation roughing and scavenging of the ball mill product to obtain a flotation concentrate; S4. The flotation concentrate is washed, then heated and activated, filtered and dehydrated to obtain activated clean coal; S5. Carry out flotation separation on the activated clean coal to obtain a clean coal product.

2. The coal preparation process and method for activating, improving quality and reducing ash of low-quality coal mines according to claim 1 is characterized in that: In step S1, the high-ash low-quality anthracite is crushed in three stages, including coarse crushing, medium crushing and fine crushing. The particle size of the crushed product obtained by screening is 1 to 3 mm, and the particle size greater than 3 mm is returned to the fine crushing step.

3. The coal preparation process and method for activating, improving quality and reducing ash of low-quality coal mines according to claim 1 is characterized in that: In step S2, the two-stage closed-circuit grinding is coarse grinding and fine grinding; the grinding is wet ball milling; the grinding aid is sodium carbonate or sodium hexametaphosphate, and the amount is 400-600 g / t; the grinding medium is steel balls or ceramic balls, the grinding concentration is 60%-70%, grinding to -0.074 mm accounts for 90-95%, and -0.044 mm accounts for 70-75%.

4. The coal preparation process and method for activating, improving quality and reducing ash of low-quality coal mines according to claim 1 is characterized in that: In step S3, the grinding product is subjected to roughing separation to obtain roughing concentrate and roughing tailings; the roughing tailings are further subjected to scavenging separation to obtain scavenging concentrate and scavenging tailings; the scavenging tailings are treated as tailings, and the scavenging concentrate and the roughing concentrate are combined as flotation concentrate.

5. The coal preparation process and method for activating, improving quality and reducing ash of low-quality coal mines according to claim 4 is characterized in that: In the roughing, the pulp concentration is 8-12%, the pH range of the roughing is 8-9, and the pH adjuster is sodium carbonate; the dispersant used in the roughing is sodium carbonate or sodium hexametaphosphate, and the usage amount is 1500-2500g / t; the inhibitor used in the roughing is sodium fluorosilicate or sodium silicate, and the usage amount is 2500-3500g / t; the collector used in the roughing is a combination of diesel and a high-efficiency combined collector, and the total usage amount of the collector is 800-1200g / t; the foaming agent used in the roughing is methyl isobutyl carbinol, and the usage amount is 300-500g / t; the order of adding drugs is pH adjuster, dispersant, inhibitor, collector, foaming agent, wherein each agent is added and stirred for 3-5 minutes, and the scraping time is 3-4 minutes; The components and proportion of the high-efficiency combined collector are: vegetable oil: emulsifier = (98-99): (1-2), wherein the vegetable oil is coconut oil, peanut oil or cottonseed oil, and the emulsifier is coconut amine.

6. The coal preparation process and method for activating, improving quality and reducing ash in low-quality coal mines according to claim 4, characterized in that: In the scavenging, the pulp concentration is 8-12%, and the pH range of the scavenging is 8-9; the dispersant used in the scavenging is sodium carbonate or sodium hexametaphosphate, and the usage amount is 500-1500g / t; the inhibitor used in the scavenging is sodium fluorosilicate or sodium silicate, and the usage amount is 1000-2000g / t; the collector used in the scavenging is a combination of diesel and a high-efficiency combined collector, and the total usage amount of the collector is 200-300g / t; the foaming agent used in the scavenging is methyl isobutyl carbinol, and the usage amount is 200-300g / t; the order of adding drugs is dispersant, inhibitor, collector, foaming agent, wherein each agent is added and stirred for 3-5 minutes, and the scraping time is 3-4 minutes; The components and proportion of the high-efficiency combined collector are: vegetable oil: emulsifier = (98-99): (1-2), wherein the vegetable oil is coconut oil, peanut oil or cottonseed oil, and the emulsifier is coconut amine.

7. The coal preparation process and method for activating, improving quality and reducing ash in low-quality coal mines according to claim 1, characterized in that: In step S4, during the washing, the ore pulp concentration is 8-12%, the detergent is 70-80% ethanol, the washing temperature is room temperature, the washing time is 5-30 minutes, mechanical stirring is adopted, and the stirring speed is 200-300 rpm.

8. The coal preparation process and method for activating, improving quality and reducing ash in low-quality coal mines according to claim 1, characterized in that: In step S4, in the heating activation, the activator is sodium hydroxide, the dosage is 8-12%, the liquid-solid ratio is controlled at (2-4):1, the heating temperature is 100-150°C, and the heating activation time is 1-2h.

9. The coal preparation process and method for activating, improving quality and reducing ash in low-quality coal mines according to claim 1, characterized in that: In step S5, the flotation separation includes separation 1 and separation 2; the pulp concentration of separation 1 and separation 2 is adjusted to 8-12% and the pH range is 8-9.

10. The coal preparation process and method for activating, improving quality and reducing ash in low-quality coal mines according to claim 9, characterized in that: The dispersant of the selected 1 is sodium carbonate or sodium hexametaphosphate, and the amount of the dispersant is 1500-3000 g / t; the inhibitor is sodium fluorosilicate or sodium silicate, and the amount of the inhibitor is 2500-3500 g / t; the collector is a combination of diesel and a high-efficiency combined collector, and the total amount of the collector is 75-125 g / t; the foaming agent is methyl isobutyl carbinol, and the amount of the foaming agent is 75-125 g / t; the selected clean coal 1 and the selected medium coal 1 are obtained, and the selected clean coal 1 is subjected to the selected 2; The dispersant for selecting 2 is sodium carbonate or sodium hexametaphosphate, and the dosage of the dispersant is 1500-3000g / t; the inhibitor is sodium fluorosilicate or sodium silicate, and the dosage of the inhibitor is 2500-3500g / t; selected clean coal 2 and flotation coal 2 are obtained, and the flotation coal 2 is returned to the selecting 1 for reselection; the selected clean coal 2 is used as the clean coal product.

Images