Method for enhancing modified coal gangue aggregate by using multi-microbial desulfurization

Abstract

The present application relates to solid waste civil engineering material application technical field, specifically relates to a kind of method for enhancing the strength of modified coal gangue aggregate by using multi-microbial desulfurization;Specifically including the domestication of strain, industrial culture, industrial treatment high-sulfur coal gangue aggregate, separation and recycling reaction substrate and reuse and the steps of industrial enhancement and modification of desulfurization coal gangue aggregate;Oxidation desulfurization bacteria is separated from the in-situ acidic wastewater of coal gangue pile burying, and its oxidation coal gangue activity is continuously domesticated and improved, and the oxidation of unstable sulfide in high-sulfur coal gangue is accelerated;The way of combination of spraying acid recovery liquid and piling up coal gangue is used, and the desulfurization oxidation efficiency is further improved;When acid recovery liquid participates in mineralization modification process, multi-solid waste and acid recovery liquid neutralization reaction occurs and Ca 2+ Because the mixed bacteria of mineralization induction has higher mineralization capacity, the generated CaCO3 fills the defects of aggregate, and improves the mechanical properties of aggregate.

Description

Technical Field

[0001] This invention relates to the field of solid waste civil engineering materials application technology, specifically to a method for enhancing the strength of modified coal gangue aggregate by utilizing multi-microbial desulfurization. Background Technology

[0002] In coal mining, coal gangue accounts for 15-20% of the raw coal output. Due to its low calorific value and combustion efficiency, coal gangue cannot be used as fuel like coal. High-sulfur coal gangue (total sulfur content ≥3%) constitutes a significant proportion of all coal gangue. Typically, coal gangue is directly piled up around coal mines, not only occupying land but also causing significant damage. Furthermore, the sulfides in high-sulfur coal gangue are easily oxidized into SO2 and H2SO4, generating acidic wastewater that pollutes the soil and causes irreversible harm to the ecological environment near coal mines. Moreover, when the heat released during oxidation accumulates to a certain level, it can easily ignite wildfires, posing a significant threat to the ecology and livelihoods of mountainous areas.

[0003] Therefore, improving the comprehensive utilization rate of high-sulfur coal gangue is of great significance for reducing coal gangue accumulation and further enhancing the economic benefits of coal-based products. Building materials are characterized by their wide range of applications and large demand. In recent years, the application of solid waste building materials has greatly promoted the disposal and utilization of solid waste. In particular, solid waste aggregates can be used in various building materials such as crushed stone bedding, concrete, and cement stabilizing materials, further improving the comprehensive utilization rate of solid waste. Coal gangue, as a natural ore, inherently possesses advantages as an aggregate, making it well-suited for aggregate applications. However, compared to natural aggregates, it has some disadvantages in mechanical properties. Furthermore, high-sulfur coal gangue also suffers from high sulfur content and unstable sulfides, which can adversely affect its subsequent application in building materials. Summary of the Invention

[0004] The purpose of this invention is to provide a method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization. This invention promotes the oxidation process of unstable sulfides in high-sulfur coal gangue, causing sulfur-containing chemical components to be oxidized into stable sulfate products in advance, and recovers and reuses the acidic recovery liquid. Then, multi-microbial mineralization is induced by immobilizing fine powder from solid waste, which participates in the enhancement and modification of the desulfurized coal gangue aggregate, filling the porosity defects and cracks in the desulfurization process, reducing the water absorption rate, and improving the mechanical properties of the coal gangue aggregate. On the one hand, this improves the comprehensive utilization rate of high-sulfur coal gangue, reduces its environmental harm, and lowers the risk of using high-sulfur coal gangue aggregate in building materials; on the other hand, the application of microbial technology throughout the modification process reduces the cost of chemical reagents and improves the efficiency of high-sulfur coal gangue aggregate modification.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for enhancing and modifying coal gangue aggregate by utilizing multi-microbial desulfurization, comprising the following steps: 1) Domestication of strains: High-oxidation-activity oxidative desulfurization mixed bacteria were obtained by separating strains from coal mine wastewater in Gaoping City and domesticating them with high-sulfur coal gangue powder suspension. High-mineralization-inducing mixed bacteria were also domesticated and screened in high-sulfur coal gangue powder suspension. 2) Industrial-scale cultivation of oxidative desulfurization mixed bacteria and application to high-sulfur coal gangue aggregate for sulfur removal, and recovery of substrate to obtain desulfurized and modified coal gangue aggregate; 3) Industrial-scale cultivation of mineralization-induced mixed bacteria, with bacterial solution immobilized on multi-component solid waste fine powder to obtain mineralization-induced mixed bacteria fine powder; 4) The desulfurized and modified coal gangue aggregate is mixed and stirred with mineralization-induced mixed bacteria fine powder. During the stirring process, the desulfurization recovery liquid is sprayed in a circulating manner to finally obtain coal gangue aggregate with desulfurization and enhanced strength.

[0006] As a further limitation of the technical solution of the present invention, the mixed bacteria for oxidation and desulfurization in step 1) are acid-resistant and heavy metal-resistant bacteria, including at least two of the following: ferrooxidizing thiobacillus, thiooxidizing thiobacillus, ferrooxidizing Leptospira, acidophilic thiobacillus, and metal sulfide leaves.

[0007] As a further limitation of the technical solution of the present invention, the oxidative desulfurization mixed bacteria are isolated from coal mine wastewater in Gaoping City, Shanxi Province, China. The specific separation and acclimatization steps are as follows: ① Wastewater from coal mines in Gaoping City was sampled multiple times from different regions and inoculated into 9K liquid culture medium. High-sulfur coal gangue powder was used as the substrate, with a solid-liquid ratio of 5% to 10%. The samples were placed in a constant temperature shaking incubator and cultured at 30±5 ℃ until the culture medium turned reddish-brown. ② After repeating the above inoculation and subculturing process 5 to 7 times, highly active bacterial strains that turn reddish-brown in culture medium and have an oxidation-reduction potential Eh ≥ 300 within 3 days are isolated and frozen at -20℃.

[0008] As a further limitation of the technical solution of the present invention, the mineralization induction mixed bacteria in step 1) are at least two of the following: urease-producing bacteria, Bacillus coliformis, Bacillus pasteurellis, and carbon-capturing carbonic anhydrase bacteria.

[0009] As a further limitation of the technical solution of the present invention, the mineralization-induced mixed bacteria are obtained by separation and domestication of high-sulfur coal gangue powder. The specific separation and domestication steps are as follows: ① The mineralization-inducing mixed bacteria were inoculated into 9K liquid medium containing high-sulfur coal gangue powder. The solid-liquid ratio of high-sulfur coal gangue powder to 9K liquid medium was 5%~20%. Then, the mixture was cultured in a constant temperature shaking incubator at 30±5 ℃ for 3 days. ② Repeat the above inoculation procedure, and periodically monitor the bacterial concentration and mineralization capacity of the strain using EDTA titration. After 3-10 repeated subculturings, strains that grow abundantly in high-sulfur coal gangue environments and exhibit strong mineralization capacity are isolated, with a bacterial concentration of 1-10 × 10⁻⁶. 10 CFU / mL, the calcium deposition rate after mineralization reaches 92%~98%.

[0010] As a further limitation of the technical solution of this invention, the industrial-scale cultivation of oxidative desulfurization mixed bacteria and its application to the desulfurization of high-sulfur coal gangue aggregate in step 2) is achieved by combining bacterial solution spraying with high-sulfur coal gangue stockpiling. Specifically, after being crushed, the high-sulfur coal gangue is stockpiled in a reaction tank, with particle sizes of 0-5 mm, 5-10 mm, and 10-30 mm. Oxidative desulfurization mixed bacteria solution is sprayed periodically at a frequency of 1-8 times / day, with a spraying cycle of 1-3 days. The substrate recovery liquid is collected and recycled for further spraying. The spraying is done from top to bottom, allowing the bacterial solution to gradually penetrate into the high-sulfur coal gangue aggregate stockpile, ensuring a large contact area and long contact time between the oxidative desulfurization mixed bacteria and the aggregate, as well as sufficient oxygen participation. During this process, the oxidative desulfurization mixed bacteria use pyrite in the high-sulfur coal gangue as a reaction substrate for growth, oxidizing the pyrite in the high-sulfur coal gangue while carrying out their life activities, thus achieving the desulfurization effect. The recovered liquid in the reaction tank contains oxidized sulfate and sulfuric acid. Recycling and reusing it helps maintain the acidic environment for the mixed bacteria in the oxidative desulfurization process, ensuring the continuous desulfurization process.

[0011] As a further limitation of the technical solution of the present invention, step 3) involves cultivating mineralization-induced mixed bacteria in an industrial microbial fermenter, and then immobilizing the bacterial solution in a solid waste fine powder with a mass ratio of 5:3:1:1 or 4:2:2:2, consisting of calcium carbide slag powder, aluminosilicate tailings powder, expanded perlite fine powder, and CFB fly ash. The solid waste fine powder is ground to 200-300 mesh before use, and the immobilization method is negative pressure adsorption with a pressure of -0.1 to -0.3 MPa. The solid waste fine powder immobilized with mineralization-induced mixed bacteria is dried and dispersed at 35 ℃ to 45 ℃, so that the mixed bacteria in the fine powder can form spores that are more adaptable to the acidic environment of desulfurized coal gangue, with a spore survival rate as high as 75% to 80%.

[0012] As a further limitation of the technical solution of this invention, in step 4), the desulfurized and modified high-sulfur coal gangue aggregate and the mineralization-induced mixed bacteria fine powder are placed into a mixing device, with an aggregate to fine powder ratio of 1 kg: 0.3~0.8 kg; first, dry mixing is performed for 30 s to ensure that the solid waste powder is evenly distributed in the pores and defects of the aggregate; then wet mixing is performed, and the acidic recovery liquid from the desulfurization and modification process is sprayed during the mixing process, with a spraying frequency of 1~5 times / day and a spraying cycle of 1~3 days. During the enhancement and modification process, the multi-element solid waste powder can neutralize the H in the acidic recovery liquid. + At the same time, Ca is released2+ This process provides a calcium source for the mineralization and modification of aggregates. The generated CaCO3 fills the defects in the aggregates and consolidates the multi-component solid waste onto the surface of the coal gangue aggregate, forming desulfurized coal gangue aggregate that can absorb multi-component solid waste and improve the mechanical properties of the aggregate. Finally, drying and dispersing in a ventilated and dry place is beneficial for the application of coal gangue aggregate in concrete and water-cooled materials.

[0013] In addition, the present invention also provides the application of modified coal gangue aggregate obtained by the above method in the preparation of mortar, filler, concrete materials, subbase, roadbed filling materials and pavement subbase and base water-stabilized materials.

[0014] Compared with the prior art, the present invention has the following beneficial effects: Oxidative desulfurizing bacteria were isolated from the in-situ acidic wastewater at coal gangue landfills and their activity in oxidizing coal gangue was continuously improved through domestication. This accelerated the oxidation of unstable sulfides in high-sulfur coal gangue, avoiding the potential environmental hazards caused by high-sulfur coal gangue while recovering the acid solution, and reducing the risks associated with the application of high-sulfur coal gangue in building materials.

[0015] The combination of stockpiling coal gangue and spraying acidic recovery liquid is beneficial for the large-scale enrichment of desulfurizing bacteria in the coal gangue pile, further improving the desulfurization and oxidation efficiency. The repeated recycling of acidic recovery liquid can save the cost of chemical reagents and help maintain the pH value of the desulfurization and modification environment.

[0016] The mineralization-induced mixed bacteria are mainly Bacillus, which, after being acclimated and dried in coal gangue powder suspension, form spores that are easy to survive in the desulfurization-modified environment of coal gangue. The use of multi-element solid waste fine powder can provide a better carrier for the mineralization-induced mixed bacteria, and provide another layer of protection for the survival of the mineralization-induced mixed bacteria in the acidic environment of desulfurization modification.

[0017] When acidic recovery liquid participates in the mineralization and modification process, the multi-component solid waste undergoes a neutralization reaction with the acidic recovery liquid and releases Ca. 2+ Because the mineralization-induced mixed bacteria have a high mineralization capacity, the generated CaCO3 fills the defects of the aggregate and improves the mechanical properties of the aggregate; at the same time, the multi-element solid waste powder is solidified on the coal gangue aggregate, which not only improves the comprehensive utilization rate of high-sulfur coal gangue, but also consumes a portion of multi-element solid waste. Attached Figure Description

[0018] Figure 1 The images show SEM images of coal gangue aggregate modified by microbial desulfurization and enhanced in Example 1 of this invention, and unmodified high-sulfur coal gangue aggregate. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments.

[0020] The strains of desulfurization mixed bacteria and mineralization-inducing mixed bacteria involved in this invention are all common and well-known strains. Example 1

[0021] Oxidative desulfurization mixed bacteria were isolated from acidic mine wastewater in a coal mine in Gaoping City, China. High-sulfur coal gangue powder was used as the substrate, and 9K medium was used as the liquid medium with a solid-liquid ratio of 5%. The culture was incubated in a constant temperature shaking incubator at 30±5℃ until it turned reddish-brown. After five repeated subculturings, a bacterial solution that turned reddish-brown within 2 days and had an oxidation-reduction potential (Eh) of 350 was isolated and further expanded in a microbial fermenter for spraying. High-sulfur coal gangue sand (0-5 mm) was loosely piled in a reaction tank, and the oxidation-inducing bacterial solution was sprayed from top to bottom twice a day. Simultaneously, the acidic recovery liquid from the reaction substrate was continuously sprayed onto the coal gangue. After 2 days of spray modification, the total sulfur content of the high-sulfur coal gangue decreased by 85%, and the pyrite (FeS2) content decreased by 98%. After spraying, the coal gangue aggregate was dried in a ventilated area until it reached a saturated surface-dry state.

[0022] Mineralization-induced mixed bacteria were acclimatized and cultured using a 5% solid-liquid ratio of coal gangue powder and 9K liquid medium. The culture was then incubated in a constant-temperature shaking incubator at 30±5 ℃ for 3 days. After three repeated subcultures, the bacterial concentration reached 2×10⁻⁶. 10 The concentration of CFU / mL was high, and the mineralization deposition rate reached 93%. The expanded culture of mineralization-induced mixed bacteria was adsorbed onto 200-mesh multi-component solid waste powder under negative pressure at -0.1 MPa. The multi-component solid waste powder consisted of calcium carbide slag powder, aluminosilicate tailings powder, expanded perlite powder, and CFB fly ash in a ratio of 5:3:1:1. Finally, the powder was dried and dispersed at 35 °C, and the spore survival rate was measured to be 78%.

[0023] Desulfurized and modified high-sulfur coal gangue aggregate and fine powder of multi-component solid waste containing mineralization-induced mixed bacteria were placed in a mixing device at a ratio of 1 kg: 0.3 kg. The mixture was first dry-mixed for 30 seconds to ensure the solid waste powder was evenly distributed throughout the pores and defects of the aggregate. Then, wet mixing was performed, spraying the acidic recovery liquid from the desulfurization modification process once a day during the mixing process. After one day of continuous mixing, the crushing index of the microbially desulfurized and enhanced coal gangue aggregate decreased from 62% to 23%, a reduction of 60-70%, upgrading it from Class III manufactured sand to Class II manufactured sand (referencing standard GBT-14684-2022 "Construction Sand"). Water absorption decreased by 50-60%.

[0024] The microbial desulfurization enhanced and modified coal gangue fine aggregate prepared in this embodiment can be applied to the preparation of mortar, filler and concrete materials. Example 2

[0025] Oxidative desulfurization mixed bacteria were isolated from acidic mine wastewater in a coal mine in Gaoping City, China. High-sulfur coal gangue powder was used as the substrate, and 9K medium was used as the liquid medium with a solid-liquid ratio of 10%. The culture was incubated in a constant temperature shaking incubator at 30±5℃ until it turned reddish-brown. After seven repeated subculturings, a bacterial solution that turned reddish-brown within 3 days and had an oxidation-reduction potential (Eh) of 400 was isolated. This solution was further expanded in a microbial fermenter for spraying. High-sulfur coal gangue coarse aggregate (10-30 mm) was loosely piled in a reaction tank, and the oxidation-inducing bacterial solution was sprayed from top to bottom at a frequency of 6 times / day. Simultaneously, the acidic recovery liquid from the reaction substrate was continuously sprayed onto the coal gangue. After 3 days of spray modification, the total sulfur content of the high-sulfur coal gangue decreased by 70%, and the pyrite (FeS2) content decreased by 95.3%. After spraying, the coal gangue aggregate was dried in a ventilated area until it reached a saturated surface-dry state.

[0026] Mineralization-induced mixed bacteria were acclimatized and cultured using a 5% solid-liquid ratio of coal gangue powder and 9K medium. The culture was then incubated in a constant temperature shaking incubator at 30±5 ℃ for 3 days. After 5 repeated subcultures, the bacterial concentration reached 8×10⁻⁶. 10 The concentration of CFU / mL was high, and the mineralization deposition rate reached 96%. The expanded culture of the mineralization-inducing mixed bacterial solution was adsorbed onto 200-mesh multi-component solid waste powder under negative pressure at -0.2 MPa. The multi-component solid waste powder consisted of calcium carbide slag powder, aluminosilicate tailings powder, expanded perlite powder, and CFB fly ash in a ratio of 5:3:1:1. Finally, the powder was dried and dispersed at 35 ℃, and the spore survival rate reached 79%.

[0027] Desulfurized and modified high-sulfur coal gangue aggregate and fine powder of multi-component solid waste containing mineralization-induced mixed bacteria were placed in a mixing device at a ratio of 1 kg: 0.6 kg. The mixture was first dry-mixed for 30 seconds to ensure the solid waste powder was evenly distributed throughout the pores and defects of the aggregate. Then, wet mixing was performed, spraying the acidic recovery liquid from the desulfurization modification process 5 times / day during the mixing process. After 3 days of continuous mixing, the crushing index of the microbially desulfurized and enhanced coal gangue aggregate decreased from 35% to 15%, a reduction of 50-70%, upgrading it from Class III crushed stone to Class II crushed stone (referencing standard GB / T14685-2022 "Construction Gravel and Crushed Stone"). Water absorption decreased by 40-65%.

[0028] The microbial desulfurization-enhanced modified coal gangue coarse aggregate prepared in this embodiment can be used in the preparation of subbase, filler and concrete materials. Example 3

[0029] Oxidative desulfurization mixed bacteria were isolated from acidic mine wastewater in a coal mine in Gaoping City, China. High-sulfur coal gangue powder was used as the substrate, and 9K medium was used as the liquid medium with a solid-liquid ratio of 8%. The culture was incubated in a constant temperature shaking incubator at 30±5℃ until it turned reddish-brown. After seven repeated subculturings, a bacterial solution that turned reddish-brown within 3 days and had an oxidation-reduction potential (Eh) of 420 was isolated. This solution was further expanded in a microbial fermenter for spraying. A uniformly mixed high-sulfur coal gangue mixture with a specific gradation (10~30 mm: 5~10 mm: 0~5 mm = 5: 2: 3) was loosely piled in the reaction tank. The gradation of the mixture was 10~30 mm: 5~10 mm: 0~5 mm = 5: 2: 3. The oxidation-inducing bacterial solution was sprayed from top to bottom at a frequency of 8 times / day, while the acidic recovery liquid from the reaction substrate was continuously sprayed onto the coal gangue. After 3 days of spray modification, the total sulfur content of high-sulfur coal gangue decreased by 80%, and the pyrite (FeS2) content decreased by 93.9%. After spraying, the coal gangue aggregate was dried in a ventilated area until it reached a saturated surface-dry state.

[0030] Mineralization-induced mixed bacteria were acclimatized and cultured using a culture medium containing coal gangue powder and liquid 9K medium with a solid-liquid ratio of 15%. The culture was then incubated in a constant temperature shaking incubator at 30±5 ℃ for 3 days. After 10 repeated subcultures, the bacterial concentration reached 9.2×10⁻⁶. 10 The concentration of CFU / mL was high, and the mineralization deposition rate reached 95%. The expanded culture of the mineralization-inducing mixed bacterial solution was adsorbed onto 200-mesh multi-component solid waste powder under negative pressure at -0.2 MPa. The multi-component solid waste powder consisted of calcium carbide slag powder, aluminosilicate tailings powder, expanded perlite powder, and CFB fly ash in a ratio of 4:2:2:2. Finally, the powder was dried and dispersed at 35 ℃, and the spore survival rate reached 83%.

[0031] Desulfurized and modified high-sulfur coal gangue aggregate and fine powder of multi-component solid waste containing mineralization-induced mixed bacteria were placed in a mixing device at a ratio of 1 kg: 0.5 kg. The mixture was first dry-mixed for 30 seconds to ensure the solid waste powder was evenly distributed throughout the pores and defects of the aggregate. Then, wet mixing was performed, spraying the acidic recovery liquid from the desulfurization modification process 4 times / day during the mixing process. After 3 days of continuous mixing, the crushing index of the microbially desulfurized and enhanced coal gangue aggregate decreased from 30% to 21%, upgrading it from Class III aggregate to Class II aggregate (referencing standard "Technical Specifications for Construction of Highway Pavement Base Course" TG / TF20-2015). Water absorption decreased by 55-65%.

[0032] The microbial desulfurization enhanced and modified coal gangue mixed aggregate prepared in this embodiment can be applied to the preparation of highway subgrade filling materials and pavement subbase and base water-stabilized materials.

[0033] The coal gangue aggregate obtained by the method of desulfurization enhancement and modification of coal gangue aggregate using multiple microorganisms according to this invention is used to prepare coal gangue subbase, coal gangue water-stabilized material, and coal gangue concrete curbstone, etc. It is a green and low-carbon road engineering material made entirely of coal gangue, replacing ordinary sand and gravel aggregates in traditional road subbase, cement-stabilized crushed stone layer and concrete curbstone. The selection of raw materials for coal gangue road engineering materials, the production, design, construction and inspection of coal gangue water-stabilized material are based on the group standard "Technical Specification for Application of Base Materials for Tunneling Coal Gangue Road" (T / CBCA 006-2020) issued by the China Bulk Cement Promotion and Development Association.

[0034] The Liduo Line Gaoping section road reconstruction project is 13.634km long. The entire reconstruction project utilizes coal gangue as the subbase, base course, and curb stones on both sides of the road. Currently, a 1km test section of the coal gangue road material has been completed. Authoritative institutions have inspected the coal gangue raw materials, coal gangue water-stabilized materials, and coal gangue concrete curb stones. On-site construction monitoring has also confirmed that the performance indicators of the coal gangue raw materials, subbase, and mixture all meet the relevant specifications and design requirements of the "Technical Specifications for Construction of Highway Pavement Base Course" (JTG / T F20-2015) and the "Technical Specifications for Application of Coal Gangue Pavement Base Course Materials in Tunneling" (T / CBCA 006-2020). The implementation of this project will be the first large-scale demonstration project in China to use all coal gangue as the road subbase, base course, and curb stones.

Claims

1. A method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization, characterized in that, Includes the following steps: 1) The domestication of strains: one method is to separate high-oxidation-activity oxidative desulfurization mixed bacteria from coal mine wastewater in Gaoping City and domesticate them in high-sulfur coal gangue powder suspension; the other method is to domesticate and screen high-mineralization-inducing mixed bacteria in high-sulfur coal gangue powder suspension. 2) Industrial-scale cultivation of oxidative desulfurization mixed bacteria and application to high-sulfur coal gangue aggregate for sulfur removal, and recovery of substrate to obtain desulfurized and modified coal gangue aggregate; 3) Industrial-scale cultivation of mineralization-induced mixed bacteria, with bacterial solution immobilized on multi-component solid waste fine powder to obtain mineralization-induced mixed bacteria fine powder; 4) The desulfurized and modified coal gangue aggregate is mixed and stirred with mineralization-induced mixed bacteria fine powder. During the stirring process, the desulfurization recovery liquid is sprayed in a circulating manner to finally obtain coal gangue aggregate with desulfurization and enhanced strength.

2. The method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization according to claim 1, characterized in that, In step 1), the oxidative desulfurization mixed bacteria are acid- and heavy metal-resistant bacteria, including at least two of the following: ferrooxidizing thiobacillus, thiosulfate thiobacillus, ferrooxidizing Leptospira, acidophilic thiobacillus, and metal sulfide leaf bacteria.

3. The method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization according to claim 2, characterized in that, The oxidative desulfurization mixed bacteria were isolated from coal mine wastewater in Gaoping City, Shanxi Province. The specific separation and acclimatization steps are as follows: ① Wastewater from coal mines in Gaoping City was sampled multiple times from different regions and inoculated into 9K liquid culture medium. High-sulfur coal gangue powder was used as the substrate, with a solid-liquid ratio of 5% to 10%. The samples were placed in a constant temperature shaking incubator and cultured at 30±5 ℃ until the culture medium turned reddish-brown. ② After repeating the above inoculation and passage process 5 to 7 times, highly active bacterial strains that turn reddish-brown in culture medium and have an oxidation-reduction potential Eh ≥ 300 within 3 days are isolated and frozen at -20℃.

4. The method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization according to claim 1, characterized in that, In step 1), the mineralization induction mixed bacteria consist of Bacillus coli and Bacillus pasteurellosis.

5. The method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization according to claim 4, characterized in that, The mineralization-induced mixed bacteria were obtained by separation and domestication using high-sulfur coal gangue powder. The specific separation and domestication steps are as follows: ① The mineralization-inducing mixed bacteria were inoculated into 9K liquid medium containing high-sulfur coal gangue powder. The solid-liquid ratio of high-sulfur coal gangue powder to 9K liquid medium was 5%~20%. Then, the mixture was cultured in a constant temperature shaking incubator at 30±5 ℃ for 3 days. ② Repeat the above inoculation procedure, and periodically monitor the bacterial concentration and mineralization capacity of the strain using EDTA titration. After 3-10 repeated subculturings, strains that grow abundantly in high-sulfur coal gangue environments and exhibit strong mineralization capacity are isolated, with a bacterial concentration of 1-10 × 10⁻⁶. 10 CFU / mL, the calcium deposition rate after mineralization reaches 92%~98%.

6. The method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization according to claim 1, characterized in that, Step 2) involves the industrial-scale cultivation of oxidative desulfurization mixed bacteria and its application in the desulfurization of high-sulfur coal gangue aggregate. This is achieved by combining bacterial solution spraying with high-sulfur coal gangue stockpiling. Specifically, after being crushed, the high-sulfur coal gangue is stockpiled in the reaction tank. The particle sizes are 0-5 mm, 5-10 mm, and 10-30 mm. Oxidative desulfurization mixed bacteria solution is sprayed periodically at a frequency of 1-8 times / day and a cycle of 1-3 days. The substrate recovery liquid is collected and recycled for further spraying. The spraying is done from top to bottom.

7. The method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization according to claim 1, characterized in that, Step 3) Cultivate mineralization-induced mixed bacteria in an industrial microbial fermenter, and then immobilize the bacterial solution in a solid waste fine powder with a mass ratio of 5:3:1:1 or 4:2:2:2, consisting of calcium carbide slag powder, aluminosilicate tailings powder, expanded perlite fine powder, and CFB fly ash. Before use, the solid waste fine powder is ground to 200-300 mesh, and the immobilization method is negative pressure adsorption with a pressure of -0.1 to -0.3 MPa. The solid waste fine powder immobilized with mineralization-induced mixed bacteria is dried and dispersed at 35 ℃ to 45 ℃, so that the mixed bacteria in the fine powder can form spores that are more adaptable to the acidic environment of desulfurized coal gangue, with a spore survival rate as high as 75% to 80%.

8. The method for enhancing and modifying coal gangue aggregate using multi-microbial desulfurization according to claim 1, characterized in that, In step 4), the desulfurized and modified high-sulfur coal gangue aggregate and the mineralization-induced mixed bacteria fine powder are put into the mixing equipment. The ratio of aggregate to fine powder is 1 kg: 0.3~0.8 kg. First, dry mix for 30 seconds to ensure that the solid waste powder is evenly distributed in the pores and defects of the aggregate. Then, wet mixing is carried out, and the acidic recovery liquid from the desulfurization modification process is sprayed during the stirring process. The spraying frequency is 1~5 times / day, and the spraying cycle is 1~3 days.

9. The application of modified coal gangue aggregate obtained by the method according to any one of claims 1-8 in the preparation of mortar and concrete materials.

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