Microbial remediation method for metal sulfide mine waste ore

Abstract

The invention discloses a microbial remediation method for metal sulfide mine waste ore. The microbial remediation method comprises the following steps: S1, screening indigenous sulfate reducing bacteria; s2, preparing a passivation material; s3, after the surface of the waste ore is flattened, a passivation material is laid; and S4, herbaceous plants and shrub plants are planted on the passivated material, and regular inspection is conducted till repairing is completed. According to the method, a microorganism and vegetation metal sulfide waste rock self-repairing system can be formed, acid production and heavy metal production of the waste rock can be inhibited, and long-acting stability of passivation of the waste rock in the metal sulfide mining area and ecological restoration is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal sulfide mine waste ore processing, in particular to a microbial remediation method for metal sulfide mine waste ore. BACKGROUND

[0002] Metal sulfide mines, such as pyrite (FeS2), chalcopyrite (CuFeS2), etc., will produce a large amount of waste ore during mining and ore dressing. These waste rocks are long-term exposed to the open air, and under the joint action of water and oxygen, a series of oxidation and decomposition reactions will occur, i.e. the formation process of "acid mine drainage (AMD)". This process not only produces high-concentration sulfuric acid, causing a sharp decrease in the pH value of the surrounding environment, but also activates and releases a large amount of heavy metal ions (such as Cu, Zn, Cd, Pb) and metalloids (such as As), causing serious and long-term pollution to the soil, surface water and groundwater in the mining area and downstream, seriously threatening the safety of the ecological system and human health.

[0003] At present, the remediation and treatment technologies for metal sulfide mine waste ore mainly include physical method, chemical method and biological method. The physical method (such as covering and landfill) has high cost and cannot fundamentally solve the problem of continuous acid production of pollution sources; the chemical method (such as adding lime and other neutralizing agents) can quickly neutralize the acid, but it is only a temporary solution and needs to be added repeatedly, which has high operating cost and is easy to produce a large amount of sludge that needs to be treated subsequently, posing a risk of secondary pollution.

[0004] In recent years, the biological remediation technology based on sulfate-reducing bacteria (SRB) has attracted widespread attention due to its environmental friendliness, low cost and sustainability. SRB can reduce sulfate (SO4 2- ) to sulfide (S 2- ) under anaerobic conditions, and the latter can react with heavy metal ions to form insoluble metal sulfide precipitates, thereby removing heavy metals from water; at the same time, this reduction reaction consumes H + , which can effectively neutralize the acidity. However, direct application of SRB to the remediation of waste ore stockpiles still faces many challenges: first, the exogenous SRB is difficult to colonize and maintain high activity in the harsh acidic, high heavy metal toxicity and nutrient-poor environment of waste ore; second, traditional SRB reactors or passive treatment systems mainly target the AMD wastewater that has been produced, and cannot effectively inhibit the acid production potential from the source (i.e. the waste ore itself); third, single microbial remediation technology often has a long remediation period, and the formed ecological system is relatively fragile and lacks stability.

[0005] Therefore, it is an urgent need in the field of mine environment management to develop a long-term and stable repair method that can inhibit the acid production and heavy metal fixation of metal sulfide waste ore from the source. A passivation material is prepared by combining high-efficiency domesticated SRB and suitable carrier materials, and is directly covered on the surface of waste ore, which can physically isolate oxygen and moisture and biologically create a local anaerobic reduction microenvironment to passivate the waste ore from the source. Further, the microbial passivation technology is combined with vegetation repair to construct a "microbe-vegetation" collaborative repair system. The plant root system can not only further stabilize the passivation material and improve the local microenvironment, but also improve the stability and sustainability of the entire repair system through ecological effects, so as to realize the in-situ self-repair of metal sulfide mine waste ore.

[0006] Based on this, the present application provides "a microbial repair method for metal sulfide mine waste ore", which aims to strengthen the indigenous SRB after screening, prepare high-efficiency passivation material, and couple with vegetation system to form a long-term and stable technology that can passivate and ecologically repair the waste ore in metal sulfide mine from the source. SUMMARY

[0007] The present application aims to solve the following key technical problems in view of the deficiencies in the existing repair technology for metal sulfide mine waste ore. 1. The traditional chemical neutralization method cannot persistently inhibit the acid production potential of waste ore from the source, and needs to repeatedly add reagents, which is high in cost and easy to cause secondary pollution.

[0008] 2. Exogenous microorganisms are difficult to colonize and maintain high activity in the harsh acid and high heavy metal environment of waste ore, resulting in unstable and long-period biological repair effect.

[0009] 3. Single repair technology (pure physical, chemical or biological) is difficult to realize long-term stability of the ecological system, and the repaired area is easy to degrade again.

[0010] The present application aims to provide a repair method based on sulfate-reducing bacteria passivation material, which can passivate metal sulfide waste ore from the source, inhibit its acid production and heavy metal release, and simultaneously realize ecological restoration.

[0011] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A microbial repair method for metal sulfide mine waste ore, comprising the following steps: S1, screening sulfate-reducing bacteria from a metal sulfide mine area; S2, preparing passivation material with 20~40g:80~120kg;320~480kg proportions of sulfate-reducing bacteria, carbon source and forest soil as raw materials; S3, surface leveling treatment is performed on the metal sulfide mine waste ore, and then the passivation material with a thickness of 40-60 cm is laid; S4, herbaceous plants and shrubs are planted on the passivation material, and the physicochemical properties of the metal sulfide mine waste ore are regularly checked until the restoration is completed.

[0012] Description: The above method can long-term and economically inhibit the oxidation and acid production process of the metal sulfide waste ore from the root cause by constructing a synergistic restoration system composed of functional microorganisms, slow-release nutrient substrates and higher plants, and can simultaneously fix the dissolved heavy metal ions; the laid passivation material layer can not only continuously neutralize the acidity and generate sulfide precipitates to efficiently immobilize heavy metals through the biological metabolism of sulfate-reducing bacteria, but also further stabilize the cover layer through the plant roots growing thereon, prevent soil erosion and strengthen the ecological restoration effect, ultimately realize the transformation from "passive treatment" of acid leachate to "active prevention" of pollution sources, and effectively promote the overall recovery and reconstruction of the ecological environment in the mining area.

[0013] Further, in S1, the sulfate-reducing bacteria are screened from the metal sulfide mine area, comprising: S1-1, collecting solid samples from the surrounding soil and river sediments of the metal sulfide mine area; S1-2, enriching and culturing the collected samples with sulfate as the substrate, and screening out sulfate-reducing bacteria and mixed microbial communities by applying low pH and / or high heavy metal concentration selection pressure; the low pH refers to pH 4-6, and the high heavy metal concentration refers to a heavy metal ion concentration of 10-100 mg / L; S1-3, preparing an acclimation medium according to the physicochemical properties of the metal sulfide mine waste ore, and obtaining sulfate-reducing bacteria by gradually increasing the concentration of target heavy metal ions in the medium and reducing the pH to acclimate the mixed microbial communities.

[0014] Description: The above method collects samples from the surrounding soil and river sediments of the metal sulfide mine, which can fully utilize local microbial resources and obtain a high adaptability of the mine environment; enriches and cultures with sulfate as the substrate and applies specific selection pressure to accurately screen out mixed microbial communities with sulfate reduction ability and tolerance to harsh conditions; and then prepares an acclimation medium according to the physicochemical properties of the mine waste ore, gradually increases the concentration of target heavy metal ions and reduces the pH for acclimation, which can directionally cultivate sulfate-reducing bacteria with strong adaptability to the mine environment, stable sulfate reduction performance and good heavy metal tolerance, providing strong strain support for subsequent efficient restoration of mine waste ore.

[0015] Further, the carbon source includes municipal sludge, pond sludge and / or organic feces with an organic matter content of more than 50%.

[0016] Description: The above-mentioned carbon source is widely available and low in cost, easy to obtain, and can reduce the cost of preparing the passivation material; high content of organic matter can be gradually decomposed under the action of microorganisms to provide sufficient and stable carbon elements and other nutrients for sulfate-reducing bacteria, ensuring their growth and metabolism activities, enhancing their activity and function, and thus more effectively participating in the repair process of metal sulfide mine waste ore; at the same time, the rational use of these carbon sources realizes the resource utilization of waste, reduces the potential pollution to the environment, and has both economic and environmental benefits.

[0017] Further, in S2, the passivation material is prepared from sulfate-reducing bacteria, carbon sources, and forest soil, comprising: The sulfate-reducing bacteria, carbon sources, and forest soil are mixed in a ratio of 20-40g:80-120kg;320-480kg to obtain the passivation material.

[0018] Description: The above-mentioned ratio can make the sulfate-reducing bacteria grow and reproduce well in the suitable environment constructed by the carbon source and the forest soil, fully exerting its biological activities of reducing sulfate and transforming heavy metals; the appropriate amount of carbon source provides sufficient energy and nutrients for the sulfate-reducing bacteria, ensuring their continuous and stable function; the forest soil not only provides a place for the microorganisms to attach, but also contains various beneficial ingredients, which can synergistically enhance the fixation and passivation effect of the passivation material on harmful substances in the metal sulfide mine waste ore, effectively improve the physicochemical properties of the ore, and improve the repair efficiency and quality.

[0019] Further, in S2, the passivation material is prepared from sulfate-reducing bacteria, carbon sources, and forest soil, comprising: S2-1, taking sulfate-reducing bacteria, carbon sources, and forest soil in a ratio of 20-40g:80-120kg;320-480kg; then mixing and fermenting the forest soil with one-third of the mass of the carbon source to obtain a pre-acidification slow-release carbon source complex particle; S2-2, pyrolyzing the remaining two-thirds of the mass of the carbon source to obtain a sludge charcoal; mixing the sludge charcoal with the sulfate-reducing bacteria agent to obtain a sludge charcoal composite bacteria paste; S2-3, wrapping the sludge charcoal composite bacteria paste on the outer surface of the pre-acidification slow-release carbon source complex particle to form a core-shell particle; curing the core-shell particle for 3-7 days to obtain the passivation material.

[0020] Description: The above preparation method can realize slow release of carbon source, provide nutrients for sulfate-reducing bacteria continuously, and prolong the action time; the residual carbon source is pyrolyzed into soil biochar, the porous structure of which can enhance the adsorption capacity, and the biochar composite bacteria paste made of the soil biochar and the sulfate-reducing bacteria can protect the bacteria agent and improve the activity and stability of the bacteria agent; the biochar composite bacteria paste is wrapped into core-shell particles, which further optimizes the synergistic effect environment of the bacteria agent and the carbon source; curing treatment makes the components fully fuse and react, and the final passivation material can more efficiently fix and transform harmful substances such as heavy metals in the mine waste rock, and significantly improve the repair effect.

[0021] Further, the curing conditions are: first, standing in a light-free sealed environment with a temperature of 20-30°C and a humidity of 90-110% for 24-30h; then, standing in a light-free sealed environment with a constant temperature and a humidity of 30-60% until the curing is completed.

[0022] Description: The above higher temperature and humidity provide a suitable and active environment for the growth and reproduction of microorganisms in the core-shell particles and the internal chemical reaction, promote the rapid adaptation of microorganisms to the new environment and the start of metabolic activity, and accelerate the preliminary fusion and reaction between the components; then, reducing the humidity can avoid the adverse effects of excessive moisture on microorganisms and material structure, and the constant temperature can maintain the stable activity of microorganisms, so that the entire passivation material is further matured and perfected in a mild and stable environment, and finally a passivation material with excellent performance and significant repair effect is obtained.

[0023] Further, in S3, the surface leveling treatment of the metal sulfide mine waste rock comprises: The metal sulfide mine waste rock is arranged to be flat, and 1-2cm of slaked lime is laid.

[0024] Description: The above surface leveling can ensure that the passivation material is in full contact with the ore and improve the repair effect; laying slaked lime can neutralize the acidic substances that may exist on the surface of the ore, adjust the local pH, improve the microorganism survival environment, and be beneficial to the growth and reproduction of beneficial microorganisms such as sulfate-reducing bacteria; on the other hand, the slaked lime can react with part of the heavy metal ions in the ore to generate insoluble precipitates, reduce the migration and bioavailability of heavy metals, and reduce the pollution risk of the surrounding environment.

[0025] Further, the regular checking of the physicochemical properties of the metal sulfide mine waste rock until the repair is completed comprises: Taking the leachate of the metal sulfide mine waste rock every month to test whether the leachate meets the index; When the leachate reaches the index, the remediation is completed; when the leachate still does not reach the index after three months, the planting density of the herbaceous plants and shrubs is increased; wherein, the judgment basis of whether the leachate reaches the index is that the leachate reaches the index when the pH is 6-8 and the removal rate of the metal ion concentration is greater than or equal to 80%, otherwise the index is not reached.

[0026] Description: The above method effectively improves the remediation efficiency and quality, and guarantees that the mine ecological remediation work steadily advances towards the expected goal.

[0027] Further, the metal sulfide mine is a lead-zinc mine, a chalcopyrite mine, a pyrite mine or a solid waste storage site.

[0028] Description: This scheme is particularly beneficial for typical metal sulfide mines such as lead-zinc, chalcopyrite and pyrite, and it can highly specifically target the strong acid, high concentration and multi-metal (such as Pb, Zn, Cu, Cd, etc.) and sulfate pollution generated in the weathering process of such ores; through the core role of sulfate-reducing bacteria, not only can the strong acidity brought by pyrite oxidation be neutralized persistently, but also the dissolved various toxic heavy metal ions can be converted into stable sulfide precipitates respectively, so as to realize the synchronous and efficient in-situ fixation of all characteristic pollutants, fundamentally curb the diffusion and migration of the pollution source to the surrounding water and soil, and provide key technical support for the ecological revival of such typical heavily polluted mines.

[0029] Advantages of the present application: Compared with the prior art, the present application has the following advantages: 1. Source control and long-term stability: The present application does not treat the generated acid wastewater, but constructs a "passivation layer" covering the waste rock to inhibit the oxidation of sulfide ore from the pollution source, and realizes long-term stability through the continuous metabolic action of SRB.

[0030] 2. Strong environmental adaptability: The use of enhanced indigenous microorganisms has natural affinity and adaptability to the local environment, avoiding the problem of "water and soil not suitable" of exogenous strains, greatly improving the success rate and stability of the remediation system.

[0031] 3. Multi-technology synergistic effect: The microbial passivation technology and vegetation restoration technology are innovatively combined. The microbial system creates a favorable rhizosphere environment for plant growth, and the plant root system provides a more stable habitat and part of the carbon source for the microorganisms, which complement each other and form a "microbe-vegetation" integrated self-repairing ecological system.

[0032] 4. Buffer design to protect microbial activity: A layer of quicklime is added as a buffer between the passivation material and waste rock, which ingeniously protects the upper layer of SRB from direct exposure to the strong acidic environment, ensuring the continuous and efficient activity of the microorganisms.

[0033] 5. Low cost and environmentally friendly: The components of the passivation material used (such as municipal sludge, pond sludge, etc.) are mostly waste resources, reducing costs, and the entire repair process does not introduce harmful chemicals, achieving green and sustainable repair.

[0034] 6. Clear quantitative indicators: The pH value of the leachate and the reduction amount of heavy metal ions are used as the criteria for determining the completion of the repair, making the repair effect measurable and assessable, ensuring the quality of the repair project. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram of the method process of an embodiment of the present application; Figure 2 is a leachate pH change trend graph during the microbial passivation process of Example 1 of the present application; Figure 3 is a leachate iron ion content change trend graph during the microbial passivation process of Example 1 of the present application; Figure 4 is a leachate manganese ion content change trend graph during the microbial passivation process of Example 1 of the present application; Figure 5 is a leachate pH change trend graph during the microbial passivation process of Example 2 of the present application; Figure 6 is a leachate copper ion content change trend graph during the microbial passivation process of Example 2 of the present application; Figure 7 is a leachate pH change trend graph during the microbial passivation process of Example 3 of the present application; Figure 8 is a leachate lead ion content change trend graph during the microbial passivation process of Example 3 of the present application; Figure 9 is a leachate zinc ion content change trend graph during the microbial passivation process of Example 3 of the present application; Figure 10 is a leachate pH change trend graph during the microbial passivation process of Example 4 of the present application; Figure 11 is a leachate iron ion content change trend graph during the microbial passivation process of Example 4 of the present application; Figure 12 is a leachate manganese ion content change trend graph during the microbial passivation process of Example 4 of the present application. DETAILED DESCRIPTION

[0036] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0037] Example 1: A microbial remediation method for waste ore from metal sulfide mines, comprising the following steps: S1. Sulfate-reducing bacteria were screened from a metal sulfide mine area; the metal sulfide mine is a pyrite mine in southern Shaanxi. like Figure 1 As shown, S1-1, solid samples were collected from the surrounding soil and river sediments of the metal sulfide mining area; S1-2. The collected samples were enriched and cultured using sulfate as a substrate, and sulfate-reducing bacteria and mixed microbial communities were screened by applying selection pressure of low pH and / or high heavy metal concentration. S1-3. Based on the physicochemical properties of the waste ore from metal sulfide mines, an acclimatization culture medium is prepared. By gradually increasing the concentration of the target heavy metal ions in the culture medium and decreasing the pH, the mixed microbial community is acclimatized to obtain sulfate-reducing bacteria.

[0038] Specifically, the methods for producing SRB solid microbial agents include: (1) Enrichment culture: SL medium was used for enrichment. The SL medium was prepared as follows: 4 mL of 60% C3H5O3Na (sodium lactate), 0.2 g / L of MgSO4·7H2O, 0.5 g / L of KH2PO4, 1 g / L of yeast extract, 10 g / L of NaCl, and 0.2 g / L of ferrous ammonium sulfate were dissolved in distilled water to a volume of 1 L and the pH was adjusted to 7.2. 47.5 mL of the solution was dispensed into 120 mL anaerobic bottles, the air was evacuated 7 times, and then sealed with butyl rubber stoppers and aluminum caps. The bottles were sterilized at 121 °C for 20 min and set aside. 2.5 g of soil or sediment samples were inoculated into the enrichment medium and cultured statically and in the dark at 30 °C.

[0039] (2) Hungate anaerobic roll tube method for strain isolation: Take 1 mL of the enriched sample and perform a 10-fold serial dilution in liquid culture medium. Use a sterile syringe to draw 0.2 mL of the serial dilution and slowly inject it along the tube wall into the solid culture medium to avoid generating air bubbles. After mixing, immediately place the tube in ice water and roll it at a uniform speed to solidify the culture medium and distribute it evenly on the tube wall. Incubate in a 30 ℃ incubator in the dark. Set up two replicates for each dilution gradient. When black colonies appear in the anaerobic tube, pick the colonies and transfer them to liquid culture medium. Incubate in a 30 ℃ incubator in the dark. After the culture medium in the anaerobic tube turns black, take 1 mL of the culture and perform another Hungate anaerobic roll tube method. Repeat the above steps at least 3 times. Transfer the strain to a new solid culture medium to obtain the original SRB strain.

[0040] (3) Enhanced domestication of SRB: The above-mentioned enriched bacterial solution was used as seed solution for gradient domestication to improve its tolerance to acidic environment and heavy metals.

[0041] Acid tolerance acclimatization: Dilute sulfuric acid was gradually added to the culture medium to lower the pH value from 7.0 to 6.5, 6.0, 5.5, 5.0 and 4.5 in sequence. After each generation of culture was stable, it was transferred to a culture medium with a lower pH.

[0042] Heavy metal tolerance acclimatization: Fe was gradually added to a culture medium at pH 4.5. 3+ Mn 2+ Pb 2+ Zn 2+ Cu 2+ A mixed solution, with concentrations ranging from low to high (e.g., Zn). 2+ (The concentration was gradually increased from 10 mg / L to 100 mg / L) for multiple generations of screening.

[0043] (4) Preparation method of solid SRB: The enhanced domesticated SRB bacterial solution was inoculated into a solid fermentation substrate with straw powder and clay minerals as the main carrier at an inoculation rate of 10%. Under suitable conditions, the culture was expanded to prepare a solid microbial agent with a water content of about 40% and an effective viable count ≥5×10⁻⁶. 8 CFU / g.

[0044] S2. Passivation materials are prepared using sulfate-reducing bacteria, carbon sources, and forest soil as raw materials; wherein the carbon source includes municipal sludge, pond mud, and / or organic feces with an organic matter content greater than 50%.

[0045] In some embodiments of the present invention, the passivation material is prepared by mixing sulfate-reducing bacteria, a carbon source, and forest soil thoroughly in a ratio of 40g:120kg:480kg to obtain the passivation material. The microbial solid inoculum is the aforementioned highly active and highly tolerant indigenous sulfate-reducing bacteria preparation that has undergone enhanced cultivation. The carbon source provides the energy and carbon necessary for microbial growth; preferably, it is a material with an organic matter content greater than 50%, such as municipal sludge, pond mud, or organic manure. The forest soil serves as a substrate to construct a suitable microbial growth environment and a foundation for plant growth.

[0046] Of the three components mentioned above, the carbon source is municipal sludge from a nearby wastewater treatment plant that has been stabilized and has an organic matter content of 55%; the forest soil is taken from the topsoil of unpolluted mountain forests around the mining area, and is sieved to remove stones and large roots.

[0047] S3. The surface of the waste ore from the metal sulfide mine is leveled, and then the passivation material with a thickness of 40-60cm is laid. Waste ore from metal sulfide mines is smoothed to a level surface and then covered with a 1-2 cm layer of slaked lime. This lime layer acts as a buffer barrier, initially neutralizing the seeping acidic water and creating a milder initial environment for the SRB in the upper passivation material. On top of the slaked lime layer, the prepared passivation material is laid to a thickness of 40-60 cm and the surface is leveled. This thickness is sufficient to form an effective physical barrier and a stable bioactive reaction layer.

[0048] S4. Plant herbaceous and shrubby plants on the passivation material, and regularly check the physicochemical properties of the waste ore from the metal sulfide mine until the remediation is completed. Take leachate from the waste ore from the metal sulfide mine monthly to test whether the leachate meets the standards; when the leachate meets the standards, the remediation is complete; if the leachate still does not meet the standards after three months, increase the planting density of herbaceous and shrubby plants; the criteria for determining whether the leachate meets the standards are: when the pH of the leachate is 6-8 and the metal ion removal rate is greater than or equal to 80%, the standards are met; otherwise, the standards are not met.

[0049] For example, after leveling the surface of the waste pyrite rock, a 2cm layer of quicklime is laid to neutralize the acidic environment of the waste rock surface, creating a milder initial environment for the SRB in the passivation material. Then, the passivation material is laid, with each square meter of waste rock surface containing 40g of microbial agent, 120kg of municipal sludge with an organic matter content of 55%, and 480kg of woodland soil. After thorough mixing, it is evenly spread on the waste rock surface. Herbaceous and shrub plants are planted on the leveled surface, and the physicochemical properties of the leachate are checked regularly until remediation is complete. Specifically, the above vegetation planting method uses locally prepared seeds, specifically: grass seed dosage 12g / m². 2 The grass species include ryegrass, broadleaf grass, sesbania, alfalfa, zoysia grass, and pig manure bean, and are covered with 2-5 cm of microbial inactivation material and rice straw to provide better conditions for growth.

[0050] Experimental Results: After vegetation growth, simulated rainfall conditions were used to analyze the physicochemical properties of the leachate to assess the remediation effect. Changes in pH, Fe, and Mn ion concentrations were selected as characteristic indicators. Figure 2 , Figure 3 as well as Figure 4 It can be seen that after 30 days of reaction, the pH of the leachate increased from 2.69 to 7.06, and the concentrations of Fe and Mn ions decreased from 189.00 mg / L and 27.62 mg / L to 1.01 mg / L and 0.77 mg / L, respectively. The metal ion removal rate was as high as 95%, achieving a very good remediation effect.

[0051] Example 2: The preparation of the microbial agent was the same as in Example 1, except that a chalcopyrite mine in Jiangxi Province was selected as a pilot site to analyze the effect of sulfate-reducing bacteria passivation material on the remediation of waste chalcopyrite ore. Specifically, after leveling the surface of the waste chalcopyrite ore, a 1.5cm layer of quicklime was laid to neutralize the acidic environment of the ore surface, creating a milder initial environment for the SRB in the passivation material. Then, a passivation agent was laid, containing 30g of the agent, 100kg of municipal sludge with an organic matter content of over 50%, and 400kg of forest soil per square meter of ore surface. After thorough mixing, the mixture was evenly spread on the ore surface. Herbaceous and shrub plants were planted on the leveled passivation layer, and the physicochemical properties of the leachate were checked regularly until remediation was completed. Specifically, the planting method involved sowing locally prepared, locally available seeds at a rate of 12g / m². 2 The grass species include centipede grass, pennisetum, bermudagrass, bahiagrass, tall fescue, white clover, etc., and are covered with 2-5 cm of microbial passivation material and rice straw to provide better conditions for growth.

[0052] Experimental Results: After vegetation growth, simulated rainfall conditions were used to analyze the physicochemical properties of the leachate to assess the remediation effect. Changes in pH and Cu ion concentration were selected as characteristic indicators. Figure 5 and Figure 6 It can be seen that after 30 days of reaction, the pH of the leachate increased from 2.50 to over 6.60, the concentration of Cu ions decreased from 33.46 mg / L to 0.88 mg / L, and the metal ion removal rate was as high as 85%, achieving a very good remediation effect.

[0053] Example 3: The preparation of the microbial agent was the same as in Example 1, except that a lead-zinc sulfide mine in Guangdong was selected as a pilot site to analyze the effect of sulfate-reducing bacteria passivation material on the remediation of waste lead-zinc ore. Specifically, after leveling the surface of the waste lead-zinc ore, a 1cm layer of quicklime was laid to neutralize the acidic environment on the surface of the waste rock, creating a milder initial environment for the SRB in the passivation material. Then, the passivation agent was laid, with each square meter of waste rock surface containing 20g of microbial agent, 80kg of municipal sludge with an organic matter content of 55%, and 320kg of forest soil. After being mixed evenly, the mixture was evenly spread on the surface of the waste rock.

[0054] Herbaceous and shrubby plants were planted on the leveled passivation layer, and the physicochemical properties of the leachate were checked regularly until the restoration was completed. Specifically, the planting method involved sowing locally prepared seeds at a rate of 12g / m². 2 The grass species include bermudagrass, bahiagrass, elephant grass, centipede grass, miscanthus, crabgrass, and edamame, and are covered with 2-5cm of microbial passivation material and rice straw to provide better conditions for growth.

[0055] Experimental Results: After vegetation growth, simulated rainfall conditions were used to analyze the physicochemical properties of the leachate to assess the remediation effect. Changes in pH, Pb, and Zn ion concentrations were selected as characteristic indicators. Figure 7 , Figure 8 as well as Figure 9 It can be seen that after 30 days of reaction, the pH of the leachate increased from 3.01 to over 6.89, and the concentrations of Pb and Zn ions decreased from 286.20 mg / L and 73.18 mg / L to 14.98 mg / L and 1.54 mg / L, respectively. The metal ion removal rate was over 90%, achieving a very good remediation effect.

[0056] Example 4: This embodiment follows the same steps as Embodiment 1, except that the application scenario is a pyrite waste rock storage site, and the specific preparation of the passivation material is as follows: S2-1. Take sulfate-reducing bacteria, carbon source, and forest soil in a ratio of 40g:120kg:480kg; then mix the forest soil with one-third of the carbon source by mass and ferment to obtain pre-acidified slow-release carbon source complex particles. The fermentation steps include: piling the mixture into a heap and carrying out anaerobic fermentation at a temperature of 55~65℃, with the pH stabilized between 6.0~7.5 for 15 days. The fermented material is then processed into uniform granules (e.g., 2cm in diameter) using a granulator to obtain pre-acidified slow-release carbon source composite granules. S2-2. The remaining two-thirds of the carbon source is pyrolyzed to obtain sludge char; sulfate-reducing bacteria agent is mixed with the sludge char to prepare biochar composite bacterial paste; the pyrolysis is specifically carried out under anaerobic conditions, heated to 500°C, pyrolyzed for 2 hours, and cooled to obtain conductive sludge char. S2-3. The biochar composite bacterial paste is coated onto the outer surface of the pre-acidified slow-release carbon source composite particles to form core-shell particles; the core-shell particles are cured for 5 days to obtain the passivated material. Specifically, a coating machine and a disc granulator are used to uniformly coat the biochar composite bacterial paste onto the outer surface of the pre-acidified slow-release carbon source composite particles.

[0057] Experimental Results: Pyrite leachate from the storage site was collected and analyzed for its physicochemical properties to assess the remediation effect. Changes in pH, Fe, and Mn ion concentrations were selected as characteristic indicators. Figure 10 , Figure 11 , Figure 12As shown, after 30 days of remediation, the pH of the leachate increased from 2.74 to 6.66, the Fe ion concentration decreased from 589.00 mg / L to 18.88 mg / L, with a Fe ion removal rate of over 96.8%, and the Mn ion concentration also decreased from 589.00 mg / L to 18.88 mg / L, with a Fe ion removal rate of over 96.8%.

[0058] Example 5: This embodiment has the same steps as embodiment 4, except that in S2-1, sulfate-reducing bacteria, carbon source, and forest soil are taken in a ratio of 20g:80kg:320kg.

[0059] Example 6: This embodiment has the same steps as embodiment 4, except that in S2-1, sulfate-reducing bacteria, carbon source, and forest soil are taken in a ratio of 30g:100kg:400kg.

Claims

1. A method for microbiological remediation of waste ore from a metal sulfide mine, characterized in that, The method comprises the following steps: S1, screening sulfate-reducing bacteria from a metal sulfide mine area; S2, preparing a passivation material from sulfate-reducing bacteria, a carbon source and forest soil in a proportion of 20-40g:80-120kg;320-480kg; S3, performing surface leveling treatment on the metal sulfide mine waste rock, and then laying the passivation material with a thickness of 40-60cm; S4, planting herbaceous plants and shrubs on the passivation material, and regularly checking the physicochemical properties of the metal sulfide mine waste rock until the repair is completed.

2. A method for the microbiological rehabilitation of waste ores from metal sulfide mines according to claim 1, characterized in that, In S1, the screening of sulfate-reducing bacteria from a metal sulfide mine area comprises: S1-1, collecting solid samples from the surrounding soil and river sediments of the metal sulfide mine area; S1-2, enriching the collected samples with sulfate as a substrate, and screening sulfate-reducing bacteria and mixed microbial communities by applying low pH and / or high heavy metal concentration selection pressure; S1-3, preparing a domestication culture medium according to the physicochemical properties of the metal sulfide mine waste rock, domesticating the mixed microbial communities by gradually increasing the concentration of target heavy metal ions in the culture medium and reducing the pH, and obtaining sulfate-reducing bacteria.

3. A method for microbiological rehabilitation of waste ore of a metal sulfide mine according to claim 1, characterized in that, The carbon source comprises municipal sludge, pond sludge and / or organic feces with an organic matter content of greater than 50%.

4. A method for microbiological rehabilitation of waste ore of a metal sulfide mine according to claim 1, characterized in that, In S2, the preparation of the passivation material from sulfate-reducing bacteria, a carbon source and forest soil comprises mixing the sulfate-reducing bacteria, the carbon source and the forest soil to obtain the passivation material.

5. A method for microbiological rehabilitation of waste ore of a metal sulfide mine according to claim 1, characterized in that, In S2, the preparation of the passivation material from sulfate-reducing bacteria, a carbon source and forest soil comprises: S2-1, taking sulfate-reducing bacteria, a carbon source and forest soil in a proportion of 20-40g:80-120kg;320-480kg, then mixing the forest soil with one-third of the mass of the carbon source and fermenting to obtain a pre-acidification slow-release carbon source composite particle; S2-2, pyrolyzing the remaining two-thirds of the mass of the carbon source to obtain a sludge charcoal, and mixing a sulfate-reducing bacteria agent with the sludge charcoal to obtain a sludge charcoal composite bacteria paste; S2-3, wrapping the sludge charcoal composite bacteria paste on the outer surface of the pre-acidification slow-release carbon source composite particle to form a core-shell particle, and curing the core-shell particle for 3-7 days to obtain the passivation material.

6. A method of microbiological rehabilitation of waste ore of a metal sulfide mine according to claim 5, characterized in that, The curing conditions are: first, standing in a light-free sealed environment with a temperature of 20-30℃ and a humidity of 90-110% for 24-30h; then, standing in a light-free sealed environment with a constant temperature and a humidity of 30-60% until the curing is completed.

7. A method for microbiological rehabilitation of waste ore of a metal sulfide mine according to claim 1, characterized in that, In S3, the surface leveling treatment on the metal sulfide mine waste rock comprises: arranging the metal sulfide mine waste rock to be flat, and laying 1-2cm of slaked lime.

8. A method for microbiological rehabilitation of waste ore of a metal sulfide mine according to claim 1, characterized in that, The regular checking of the physicochemical properties of the metal sulfide mine waste rock until the repair is completed comprises: taking the leachate of the metal sulfide mine waste rock every month, and testing whether the leachate meets the index; When the leachate reaches the index, the remediation is completed; when the leachate still does not reach the index after three months, the planting density of the herbaceous plants and the shrubs is increased; wherein, the judgment basis of whether the leachate reaches the index is that the leachate reaches the index when the pH is 6-8 and the removal rate of the metal ion concentration is greater than or equal to 80%, otherwise the leachate does not reach the index.

9. A method for microbiological rehabilitation of waste ore of a metal sulfide mine according to claim 1, characterized in that, The metal sulfide mine is a lead-zinc mine, a chalcopyrite mine, a pyrite mine or a solid waste storage site.

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