Method for enriching sulfur resources in high-sulfur coal gangue and upgrading and recovering low-ash carbon

Abstract

The application discloses a method for enriching sulfur resources in high-sulfur coal gangue and recovering low-ash carbon quality, which comprises the following steps: 1) grading and crushing the high-sulfur coal gangue, then performing liquid-phase grinding and dissociation, filtering and drying to obtain high-sulfur coal gangue powder; 2) adding inhibitors, collectors and foaming agents to the high-sulfur coal gangue powder after slurry preparation to perform flotation, thereby obtaining sulfur concentrate and flotation tailings; 3) performing flocculation, thickening, dehydration, filtration and drying on the sulfur concentrate to obtain high-purity sulfur concentrate products; and 4) performing slurry preparation on the flotation tailings after filtering and drying, then performing gravity separation to obtain low-ash clean coal and fine gangue. The method realizes accurate separation of coal, gangue and sulfide ore through efficient separation technology, optimization of flotation process structure and accurate control of process conditions, and has the advantages of high recovery rate, high product quality, simple process flow, low production cost and the like, and has important significance for alleviating sulfur resource shortage and promoting green transformation of the coal industry.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue. Background Technology

[0002] Coal gangue is a typical associated solid waste generated during coal mining and washing processes, with a lower heating value generally below 6.3 MJ·kg⁻¹. -1 Coal gangue is rich in inorganic ash such as alumina and silica, accounting for 60-95% of its mass. Due to the difficulty in resource utilization, it was long regarded as industrial solid waste for disposal. In recent years, significant progress has been made in the research and development and industrial application of high-value utilization technologies for coal gangue. The core directions cover multiple fields such as mine filling (e.g., using coal gangue to fill abandoned goaf areas to achieve volume reduction and geological environment restoration), fuel modification (e.g., adding coal gangue powder as an additive to raw coal to optimize combustion conditions and improve combustion efficiency), soil improvement (e.g., using it to improve soil structure and supplement mineral nutrients after harmless treatment), extraction of valuable components (e.g., targeted recovery of metals and non-metals such as aluminum, silicon, and iron), and building material preparation (e.g., producing new building materials such as gangue bricks, concrete aggregates, and ceramsite).

[0003] It is noteworthy that research on the utilization of coal gangue aggregates is particularly lacking in technological exploration for high-sulfur coal gangue, even though this category constitutes a major component of my country's coal gangue resources. As a by-product of coal mining and washing, my country's annual production of high-sulfur coal gangue has reached 700-800 million tons, with a cumulative stockpile of up to 6 billion tons, accounting for the largest share of total coal gangue reserves. In terms of composition, sulfur in high-sulfur coal gangue mainly exists in the form of organic and inorganic sulfur, with inorganic sulfur dominating—especially in my country's high-sulfur coal mining areas, where pyrite is the primary inorganic sulfur carrier and possesses extremely strong oxidizing activity. The oxidation process of pyrite not only poses serious environmental and safety hazards but also wastes valuable resources: shallow oxidation releases SO2 gas, polluting the atmosphere; deep oxidation produces sulfuric acid, forming acidic mine wastewater that causes irreversible ecological damage to surrounding soil and water bodies; simultaneously, the entire oxidation reaction is accompanied by continuous heat release, and when the heat accumulates to a critical value, it ignites surrounding combustibles, becoming the core cause of spontaneous combustion in coal gangue piles in mining areas. If untreated high-sulfur coal gangue is directly used as building aggregate, the acidic substances produced by oxidation will corrode cement mortar and steel bars, and the potential high temperature of spontaneous combustion will directly threaten the structural safety of buildings, putting its resource utilization in a dilemma of "high risk and low compatibility".

[0004] In fact, high-sulfur coal gangue not only contains sulfur elements that need to be controlled, but also contains recoverable sulfur resources and low-ash carbonaceous matter. If relevant technologies can be used to achieve efficient separation of coal, gangue, and pyrite, high-purity pyrite concentrate and high-quality clean coal can be recovered. The recovered pyrite is a key industrial raw material for the production of sulfuric acid, sulfur refining, and the manufacture of iron-based products, while the high-quality clean coal can be used as a high-quality fuel or chemical raw material. This process perfectly embodies the circular economy concept of "turning waste into treasure" and has significant economic value. However, existing technologies are not yet fully capable of comprehensively recovering and utilizing sulfur resources and low-ash carbonaceous matter from high-sulfur coal gangue, and there are problems such as low recovery efficiency, low product purity, and complex process flow. Although some methods can achieve the separation of some components, it is difficult to obtain high-purity pyrite concentrate and high-quality clean coal simultaneously, and secondary pollution is easily generated during the treatment process, increasing subsequent treatment costs. In addition, existing technologies lack specific design for the occurrence state and distribution characteristics of different components in high-sulfur coal gangue, resulting in the separation effect being greatly affected by fluctuations in the properties of raw materials, making it difficult to achieve stable industrial application.

[0005] In the coal industry, flotation technology is mainly used for partial separation and recovery of coal slime. Its process structure and reagent regime are insufficient to meet the requirements for deep desulfurization, ash reduction, and quality improvement of high-sulfur coal gangue. Currently, the reagent regimes used in flotation are relatively simple, with collectors primarily consisting of diesel and kerosene. Research on reagents commonly used in non-ferrous metal beneficiation that enhance separation effects, such as activators, inhibitors, dispersants, and modifiers, remains relatively weak. Regarding the flotation process structure, coal preparation operations typically include only 1-2 cleaning stages (sometimes in an open-circuit manner), and generally lack a scavenging stage, resulting in generally low flotation recovery rates (mostly below 80%), which increases the production cost of clean coal. Furthermore, the insufficient number of cleaning stages, coupled with the gradually decreasing floatability differences between sulfur and ash minerals and coal during the cleaning process, limits further reduction of sulfur and ash content in the clean coal. Current conventional coal preparation processes often fall into a dilemma: if low sulfur and low ash are pursued, the recovery rate will decrease significantly, resulting in resource waste; if maintaining the recovery rate is prioritized, it will be difficult to improve the removal of ash and sulfur, leading to an awkward situation where product quality is "neither high nor low". Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide a method for enriching sulfur resources and recovering low-ash carbonaceous matter from high-sulfur coal gangue, aiming to achieve precise separation of coal, gangue, and sulfide ore through efficient sorting technology.

[0007] The objective of this invention is achieved through the following technical solution: A method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter from high-sulfur coal gangue includes the following steps: 1) After classifying and crushing the high-sulfur coal gangue, liquid-phase grinding and dissociation are carried out, followed by filtration and drying to obtain high-sulfur coal gangue powder. 2) After adjusting the high-sulfur coal gangue powder from step 1), add inhibitors, collectors and frothers for flotation to obtain sulfur concentrate and flotation tailings; 3) After flocculation sedimentation, thickening and dehydration, filtration and drying of the sulfur concentrate in step 2), a high-purity sulfur concentrate product is obtained. 4) After filtering and drying, the flotation tailings from step 2) are pulped and separated by gravity separation to obtain low-ash clean coal and fine-grained gangue.

[0008] In some specific embodiments, the particle size of the high-sulfur coal gangue after grading and crushing in step 1) is <1mm.

[0009] In some specific embodiments, during the liquid-phase grinding and dissociation process described in step 1), the solid content of the grinding slurry is 40-80%, and the mass percentage of high-sulfur coal gangue powder with a particle size of ≤0.075mm in the obtained dissociated slurry is 80-95%.

[0010] Furthermore, in the liquid phase grinding and dissociation process described in step 1), the solid content of the grinding slurry is 30-70%, and the mass percentage of high-sulfur coal gangue powder with a particle size of ≤0.075mm in the obtained dissociated slurry is 90-95%.

[0011] In some specific embodiments, the liquid phase grinding and dissociation time in step 1) is 1 min to 20 min, preferably 5 min to 15 min, and more preferably 8 min to 10 min.

[0012] In some specific embodiments, the concentration of the flotation pulp in step 2) is 80-200 g / L. In some specific embodiments, the collector in step 2) is a mixture of isobutyl xanthate, pentyl xanthate and thiouric acid ester in a mass ratio of 100:(25-45):(10-20).

[0013] In some specific embodiments, the inhibitor in step 2) is a mixture of sodium lignosulfonate, water glass and modified starch in a mass ratio of 10:(3-8):(0.5-2).

[0014] In some specific embodiments, the dosage of the inhibitor in step 2) is 3000-6000 g / t, the dosage of the collector in step 2) is 500-2000 g / t, and the dosage of the frother in step 2) is 500-3000 g / t (the dosage specifically refers to the dosage of inhibitor / collector / frother per ton of high-sulfur coal gangue dry material as 800-1500 g).

[0015] Furthermore, the dosage of the inhibitor in step 2) is 3000-5000 g / t, the dosage of the collector in step 2) is 800-1500 g / t, and the dosage of the foaming agent in step 2) is 500-1000 g / t.

[0016] In some specific implementations, the flotation process in step 2) is as follows: the number of coarse flotation cycles is 1, and the number of fine flotation cycles is 1 to 5.

[0017] In some specific embodiments, the pulp concentration is 10-40% during the gravity separation process described in step 4).

[0018] In some specific implementations, during the gravity separation process described in step 4), the gravity feed rate is 0.5-3 t / h.

[0019] Furthermore, in the gravity separation process described in step 4), the gravity feed rate is 1-2 t / h.

[0020] In some specific embodiments, during the gravity separation process described in step 4), the opening degree of the discharge port of the light component is 10-40%, and the opening degree of the discharge port of the heavy component is 0%.

[0021] Compared with the prior art, the present invention has at least the following advantages: 1) The method for resource enrichment and low-ash carbonaceous material upgrading and recovery of sulfur from high-sulfur coal gangue provided by this invention firstly ensures the full dissociation of intergrowths in high-sulfur coal gangue by precisely controlling process parameters such as the solid content of grinding slurry and grinding time; then, it achieves efficient separation of sulfur from coal and gangue through flotation; next, it enhances the selective collection of target sulfur-containing minerals by precisely designing and controlling the flotation reagent system and using a composite collector system, while effectively inhibiting the flotation of coal and gangue minerals with composite inhibitors, thereby significantly improving the recovery rate and product purity of sulfur concentrate; at the same time, it further reduces impurity entrainment by optimizing the "roughing-cleansing" flotation process structure and reasonably increasing the number of cleaning stages, ensuring the stable improvement of sulfur concentrate quality; finally, it utilizes the density difference between coal and gangue to separate the flotation tailings into low-ash clean coal and fine-grained gangue through gravity separation. The fine-grained gangue can be directly used for land reclamation or as building material; the low-ash clean coal product can be used as high-quality fuel or chemical raw material.

[0022] 2) This method achieves precise separation of coal, gangue and sulfide ore through efficient separation technology, optimized flotation process structure and precise control of process conditions. It has the advantages of high recovery rate, excellent product quality, simple process and low production cost, which is of great significance for alleviating the shortage of sulfur resources and promoting the green transformation of the coal industry. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0024] Figure 1 This is a flowchart of the deep deashing and upgrading flotation process in the method for resource enrichment and low-ash carbonaceous material upgrading and recovery of sulfur from high-sulfur coal gangue provided by the present invention. Figure 2 The flowchart shows the gravity separation process in the high-sulfur coal gangue sulfur resource enrichment and low-ash carbonaceous material upgrading and recovery method provided by the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0026] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values ​​with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values ​​listed herein include the endpoints of the range and all integers and fractions within that range.

[0027] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.

[0028] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.

[0029] In the following examples, high-sulfur coal gangue from Bijie, Guizhou Province, with an ash content of 76.39% and a sulfur content of 6.63%, was used as raw material. Example 1:

[0030] The present invention provides a method for sulfur resource enrichment and low-ash carbonaceous material upgrading and recovery from high-sulfur coal gangue, which includes the following steps: 1) The high-sulfur coal gangue is graded and crushed to control the particle size of the high-sulfur coal to <1mm, and the intergrowths in the high-sulfur coal gangue are initially dissociated. The crushed high-sulfur coal gangue with a particle size of <1mm is added to a ball mill for liquid phase grinding and dissociation. Water is added to control the grinding slurry concentration to 50%, and the grinding time is 10min. The fineness of the slurry obtained after grinding and dissociation is ≤0.075mm, accounting for 90%. The fully dissociated slurry is then filtered and dried to obtain high-sulfur coal gangue powder. 2) Flotation After being finely crushed, ground, and fully dissociated, the powdered high-sulfur coal gangue is slurried and added to a flotation cell. Inhibitors, collectors, and frothers are added in sequence. The mineral processing is carried out according to a process of one roughing and five cleaning cycles to obtain sulfur concentrate and flotation tailings. The sulfur concentrate is then subjected to flocculation sedimentation, thickening and dewatering, filtration, and drying to obtain a high-purity sulfur concentrate product. The inhibitor is a mixture of sodium lignosulfonate, water glass, and modified starch in a mass ratio of 10:5:1, with a dosage of 4000 g / t; the collector is a mixture of isobutyl xanthate, pentyl xanthate, and thiouric acid ester in a mass ratio of 100:35:15, with a dosage of 1000 g / t; the frother is 2-octanol, with a dosage of 500 g / t; and the pulp concentration during flotation is 150 g / L. 3) Reselect The flotation tailings obtained in step (2) are filtered and dried and then pulped for gravity separation. The gravity feed rate is 1.5 t / h, the pulp concentration is 20%, the opening of the discharge port of the light component of gravity separation is 25%, and the opening of the discharge port of the heavy component of gravity separation is 0%, so as to obtain low-ash clean coal and fine-grained gangue.

[0031] Experimental results under the above experimental conditions: Example 2:

[0032] Compared with Example 1, the only difference is the grinding and dissociation time: Group (I): 5 min; Group (II): 15 min.

[0033] The test results are as follows: Example 3:

[0034] Compared with Example 1, the only difference is the grinding concentration: Group (I): 30%; Group (II): 70%.

[0035] The test results are as follows: Example 4:

[0036] Compared with Example 1, the only difference is that the feed rate is 2t / h.

[0037] The test results are as follows: Example 5:

[0038] Compared with Example 1, the only difference is the flotation pulp concentration: Group (I): 80 g / L; Group (II): 200 g / L.

[0039] The test results are as follows: Example 6:

[0040] Compared with Example 1, the only difference is the type of collector: Group (I): Butyl xanthate; Group (II): Thioamino ester; Group (III): Amyl xanthate.

[0041] The test results are as follows: Example 7:

[0042] Compared with Example 1, the only difference is the type of inhibitor: Group (I): calcium lignosulfonate; Group (II): water glass; Group (III): modified starch.

[0043] The test results are as follows: Example 8:

[0044] Compared with Example 1, the only difference is the opening of the discharge port of the light component: Group (I): 10%; Group (II): 40%.

[0045] The test results are as follows: Example 9:

[0046] Compared with Example 1, the only difference is the concentration of gravity separation pulp: Group (I): 10%; Group (II): 40%.

[0047] The test results are as follows: In summary, as demonstrated in Example 19, a process combining grinding, dissociation, flotation, and gravity separation can achieve efficient separation of coal, gangue, and sulfur, yielding low-ash, low-sulfur clean coal and high-purity sulfur concentrate. The separation effect is closely related to factors such as grinding and dissociation time, gravity feed concentration and discharge port opening, flotation reagent regime, and process structure. Comparison of the various examples shows that deviations from any key process parameter will lead to a significant decrease in separation indicators. However, through synergistic optimization and parameter matching of the grinding, gravity separation, and flotation stages, high yields of gravity separation intermediate products, low-ash, low-sulfur flotation clean coal, and high-grade flotation sulfur concentrate can be achieved simultaneously, thus verifying the necessity and superiority of the process parameter combination provided by this invention.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter from high-sulfur coal gangue, characterized in that, Includes the following steps: 1) After classifying and crushing the high-sulfur coal gangue, liquid-phase grinding and dissociation are carried out, followed by filtration and drying to obtain high-sulfur coal gangue powder. 2) After adjusting the high-sulfur coal gangue powder from step 1), add inhibitors, collectors and frothers for flotation to obtain sulfur concentrate and flotation tailings; 3) After flocculation sedimentation, thickening and dehydration, filtration and drying of the sulfur concentrate in step 2), a high-purity sulfur concentrate product is obtained. 4) After filtering and drying the flotation tailings from step 2), the slurry is pulverized and subjected to gravity separation to obtain low-ash clean coal and fine-grained gangue.

2. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 1, characterized in that, The particle size of the high-sulfur coal gangue after grading and crushing in step 1) is <1mm.

3. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 2, characterized in that, In the liquid-phase grinding and dissociation process described in step 1), the solid content of the grinding slurry is 30-70%, and the mass percentage of high-sulfur coal gangue powder with a particle size of ≤0.075mm in the obtained dissociated slurry is 80-95%.

4. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 1, characterized in that, The collector mentioned in step 2) is a mixture of isobutyl xanthate, pentyl xanthate and thiouric acid ester in a mass ratio of 100:(25-45):(10-20).

5. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 4, characterized in that, The inhibitor in step 2) is a mixture of sodium lignosulfonate, water glass and modified starch in a mass ratio of 10:(3-8):(0.5-2).

6. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 5, characterized in that, The dosage of the inhibitor in step 2) is 3000-6000 g / t, the dosage of the collector in step 2) is 500-2000 g / t, and the dosage of the foaming agent in step 2) is 500-3000 g / t.

7. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 6, characterized in that, The flotation process described in step 2) is as follows: the number of roughing operations is 1, and the number of cleaning operations is 1 to 5.

8. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 1 or 5, characterized in that, In the gravity separation process described in step 4), the pulp concentration is 10-40%.

9. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 8, characterized in that, In the gravity separation process described in step 4), the gravity feed rate is 0.5-3 t / h.

10. The method for enriching sulfur resources and upgrading and recovering low-ash carbonaceous matter in high-sulfur coal gangue according to claim 9, characterized in that, In the gravity separation process described in step 4), the opening degree of the discharge port of the heavy component is ≤50%, and the opening degree of the discharge port of the light component is ≤50%.

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