A complex polymetallic tailings resource utilization leaching method based on microbial in-situ activation

Abstract

The application is suitable for the technical field of bio-metallurgy and solid waste resource, and provides a complex multi-metal tailing resourceization leaching method based on microbial in-situ activation. The application constructs a sacrificial interface layer on the surface of sulfide ore through a double-response type silane coupling agent containing a disulfide bond, which is broken under the response of oxidation-reduction potential, and the released mercapto reacts with modified tannic acid and anthraquinone electron mediator to form covalent anchoring, thereby constructing a hierarchical electron transfer network of in-situ anchoring-solution phase efficient conduction-immobilized terminal receiving. 3+ Iron precipitation is inhibited; and the three form a synergistic mechanism of interface protection-iron complexation-electron conduction, so that the leaching system enters a self-sustaining and efficient state which is continuously inhibited, and the leaching rate of valuable metals such as copper and zinc is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of biometallurgy and solid waste resource utilization technology, and particularly relates to a leaching method for the resource utilization of complex polymetallic tailings based on in-situ activation of microorganisms. Background Technology

[0002] Complex polymetallic tailings often contain valuable metals such as copper, zinc, gold, and silver. However, due to their fine mineral distribution, complex symbiotic relationships, and the presence of a large number of sulfide minerals (such as chalcopyrite and pyrite), they face severe passivation problems when using traditional bioleaching.

[0003] During bioleaching, a dense elemental sulfur film and a precipitate layer of potassium sulfide alum are easily formed on the surface of sulfide minerals under oxidation. The formation of the elemental sulfur film is due to the obstructed electron transport pathways released during the oxidation of sulfide minerals, leading to the accumulation and crystallization of elemental sulfur on the surface. The precipitate of potassium sulfide alum originates from Fe in the solution. 3+ Hydrolytic deposition occurs on the mineral surface; these two passivation layers work together to hinder the leaching agent (Fe). 3+ Contact between the metal and the fresh mineral surface causes the reaction to terminate prematurely, and the target metal (copper, zinc, etc.) becomes trapped and difficult to leach, with the metal leaching rate generally below 50-60%. Even with microbial leaching, the passivation layer forms faster than the microbial repair rate, becoming the core bottleneck restricting the development of biometallurgical technology.

[0004] To address the passivation problem, existing technologies have explored various approaches: adding surfactants (such as sodium dodecyl sulfate) to alter mineral surface properties and attempt to prevent sulfur film spreading; introducing soluble electron mediators (such as anthraquinone compounds) to enhance electron transfer; and adding complexing agents (such as EDTA and citric acid) to complex iron ions and inhibit iron precipitation. However, these individual approaches have significant drawbacks: surfactants can only partially inhibit sulfur film formation and cannot solve the problems of iron precipitation and electron accumulation; soluble electron mediators are easily washed away by the solution, resulting in poor persistence; and complexing agents are costly and may complex the target metal, affecting subsequent recovery. Summary of the Invention

[0005] This invention provides a leaching method for complex polymetallic tailings based on in-situ microbial activation, aiming to solve the problem of low metal leaching rate caused by the continuous formation of passivation layer during the bioleaching process of complex polymetallic tailings.

[0006] This invention is implemented as follows: a method for resource leaching of complex polymetallic tailings based on in-situ microbial activation, comprising the following steps: S1. Tailings pretreatment and interface reconstruction: Tailings are mixed with a dual-responsive silane coupling agent containing disulfide bonds, so that the coupling agent forms coordination bonds with metal atoms on the surface of sulfide minerals through its mercapto groups, thereby forming a sacrificial interface layer on the surface of sulfide minerals. S2. Construction of immobilized electron mediator filler: Carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material was loaded onto a porous support and placed in a bioleaching reactor as an immobilized electron mediator filler; S3. Inoculation with microorganisms and leaching operation: Add Leptospirillum ferriphilum bacterial solution to the reactor and add modified tannic acid, and carry out bioleaching under stirring or circulating spray conditions; the modified tannic acid is obtained by reacting tannic acid with acryloyl chloride, and the carbon-carbon double bond contained in its molecule can chemically react with the thiol group exposed after the dual-responsive disulfide bond-containing silane coupling agent is broken to form a covalent bond; S4. Leachate treatment and recycling: After solid-liquid separation, the leachate is directly subjected to solvent extraction to recover the target metal. The raffinate is replenished with iron complexing agent and nutrients and then returned to the reactor for recycling.

[0007] Preferably, the preparation method of the dual-responsive disulfide-bonded silane coupling agent is as follows: (a) Dissolve γ-mercaptopropyltrimethoxysilane in anhydrous ethanol, add an oxidant to carry out an oxidative coupling reaction at a temperature of 20-40°C for 6-24 hours, remove the solvent by vacuum distillation to obtain the intermediate product. (b) Dissolve the intermediate product in an anhydrous organic solvent, add an acylation reagent and a base, react at 0-30°C for 2-8 hours, wash, dry, and concentrate under reduced pressure to obtain a dual-responsive silane coupling agent containing disulfide bonds.

[0008] A dual-responsive disulfide-bonded silane coupling agent forms a sacrificial interface layer on the surface of sulfide minerals. This interface layer exhibits microbial responsiveness: in the initial stage of leaching, the disulfide bonds are in a stable state, forming a dense sacrificial layer that alters the surface energy, preventing the elemental sulfur generated by oxidation from spreading and crystallizing, and causing it to detach as nanoparticles; simultaneously, the interface layer chelates Fe in the solution. 3+ This inhibits hydrolysis and precipitation. As the metabolic activity of Leptospira ironophila increases, the redox potential of the system rises, disulfide bonds break, and active thiol groups are released. The released active thiol groups can undergo nucleophilic addition reactions with the carbon-carbon double bonds on the modified tannic acid molecules (under acidic conditions (pH 1.8-2.2) and at room temperature (30-40℃)) to form stable thioether bonds. At the same time, anthraquinone-2-sulfonic acid or its oligomers in the solution can be adsorbed onto the mineral surface or modified tannic acid molecules through non-covalent interactions and participate in the electron transfer process.

[0009] Preferably, in step (a), the molar ratio of γ-mercaptopropyltrimethoxysilane to the oxidant is 1:0.3-1:0.8, and the oxidant is elemental iodine or hydrogen peroxide.

[0010] Preferably, in step (b), the molar ratio of the intermediate product to the acylation reagent is 1:0.8-1:1.5, and the molar ratio of the intermediate product to the base is 1:0.5-1:2; the acylation reagent is acetyl chloride or tert-butyl chloride, the base is triethylamine, pyridine or 4-dimethylaminopyridine, and the anhydrous organic solvent is dichloromethane, trichloromethane, acetonitrile or tetrahydrofuran.

[0011] Preferably, the preparation method of the carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material is as follows: (1) Carboxylated multi-walled carbon nanotubes were ultrasonically dispersed in water, and sodium anthraquinone-2-sulfonate was added and stirred to dissolve; (2) Under nitrogen protection, heat to 60-80℃, add oxidant, and react for 4-8 hours; (3) The product was centrifuged, washed and dried to obtain carbon nanotube grafted polyanthraquinone-2-sulfonic acid composite material.

[0012] The carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material is loaded on porous carbon felt to form an immobilized electron mediator filler. It has a high specific surface area and excellent conductivity, and can be used as an electron sink to efficiently receive electrons exported from the mineral surface through the solution phase, thereby reducing the electron density in the solution and providing a continuous driving force for electron export from the mineral surface.

[0013] Preferably, the mass ratio of the carboxylated multi-walled carbon nanotubes to sodium anthraquinone-2-sulfonate is 1:1 to 1:3, the oxidant is ammonium persulfate or ferric chloride, and the molar ratio of the oxidant to sodium anthraquinone-2-sulfonate is 1:1 to 2:1.

[0014] Preferably, the modified tannic acid is added at a concentration of 50-200 mg / L, and its preparation method is as follows: tannic acid is dissolved in anhydrous tetrahydrofuran, and triethylamine is added as an acid-binding agent, wherein the molar ratio of triethylamine to acryloyl chloride is 1.0:1~1.5:1. Acryloyl chloride is added dropwise in an ice bath at 0-5℃, and the reaction is carried out at room temperature for 4-6 hours. The mixture is then filtered, concentrated, precipitated, and dried to obtain modified tannic acid; wherein the mass ratio of acryloyl chloride to tannic acid is 1:3 to 1:1. Preferably, the temperature for bioleaching in step S3 is 30-40℃, the initial pH is 1.8-2.2, and the leaching cycle is 10-20 days.

[0015] Preferably, the porous carrier is a porous carbon felt, and the mass ratio of the carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material to the porous carbon felt is 1:5-1:20.

[0016] Preferably, the inoculum amount of *Leptospira ferrophila* culture is 2%-10% of the effective volume of the reactor, and the bacterial concentration is ≥1×10⁻⁶. 8 cells / mL.

[0017] Compared with the prior art, the embodiments of this application have the following main advantages: The leaching method for complex polymetallic tailings based on in-situ microbial activation provided by this invention forms a sacrificial interface layer on the surface of sulfide ore using a dual-responsive disulfide-bonded silane coupling agent to prevent sulfur film spreading. During leaching, the disulfide bonds break, releasing active thiol groups. The broken thiol groups react chemically with the carbon-carbon double bonds in the modified tannic acid molecules to form a stable covalent anchor. Simultaneously, the carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material can release trace amounts of anthraquinone-2-sulfonic acid oligomers during leaching. These oligomers adsorb onto the mineral surface or modified tannic acid molecules through non-covalent interactions, participating in electron transfer and fixing the electron mediator in situ on the mineral surface, constructing direct electron extraction sites. The carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material immobilized on porous carbon felt acts as an electron sink, efficiently receiving electrons extracted from the mineral surface through the solution phase, constructing a hierarchical electron transfer network, and eliminating electron accumulation on the mineral surface from the root. Simultaneously, the phenolic hydroxyl groups retained by the modified tannic acid in situ complex Fe... 3+ It inhibits iron precipitation; the three components complement each other, forming a synergistic mechanism of interface protection, iron complexation, and electron extraction, enabling the leaching system to enter a self-sustaining high-efficiency state in which passivation is continuously inhibited, and significantly improving the leaching rate of valuable metals such as copper and zinc. Attached Figure Description

[0018] Figure 1 This is a flowchart of a complex polymetallic tailings resource leaching method based on in-situ microbial activation provided by the present invention. Detailed Implementation

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] Example 1 This invention provides a method for the resource leaching of complex polymetallic tailings based on in-situ microbial activation, such as... Figure 1 As shown, it includes the following steps: S1. Preparation of dual-responsive disulfide-bonded silane coupling agents (1) Dissolve 0.1 mol γ-mercaptopropyltrimethoxysilane in 100 mL of anhydrous ethanol, add 0.05 mol iodine, stir at 30 °C for 12 hours to carry out oxidative coupling reaction, and remove the solvent by vacuum distillation after the reaction is completed to obtain the intermediate product bis(trimethoxysilylpropyl) disulfide.

[0022] (2) Dissolve 0.05 mol of the above intermediate product in 50 mL of anhydrous dichloromethane, add 0.06 mol of triethylamine, and slowly add 0.05 mol of acetyl chloride under ice bath conditions. After the addition is complete, raise the temperature to 25 °C and react for 4 hours. After the reaction is complete, wash with saturated sodium bicarbonate solution and deionized water in sequence, dry with anhydrous sodium sulfate, concentrate under reduced pressure to obtain a dual-response type disulfide bond silane coupling agent.

[0023] S2. Construction of Immobilized Electron Mediator Filler (1) Disperse 1g of carboxylated multi-walled carbon nanotubes ultrasonically in 200mL of deionized water, add 2g of anthraquinone-2-sulfonate sodium, and stir to dissolve.

[0024] (2) Under nitrogen protection, the temperature was raised to 70°C, 1.5g of ammonium persulfate was added, and the reaction was carried out for 6 hours.

[0025] (3) The reaction product was centrifuged, washed three times with deionized water, and vacuum dried at 60°C for 12 hours to obtain carbon nanotube grafted polyanthraquinone-2-sulfonic acid composite material.

[0026] (4) The above composite material and porous carbon felt are mixed at a mass ratio of 1:10. The carbon nanotube grafted polyanthraquinone-2-sulfonic acid composite material is ultrasonically dispersed in deionized water to prepare a dispersion of 2 g / L. The porous carbon felt is immersed in the dispersion, degassed under vacuum for 30 minutes, and then dried at 80°C for 12 hours. The immersion-drying process is repeated twice to ensure that the composite material is uniformly loaded on the surface of the carbon felt fiber to obtain an immobilized electron mediator filler, which is then placed in a bioleaching reactor.

[0027] S3. Preparation and Leaching Operation of Modified Tannic Acid (1) Preparation of modified tannic acid: Dissolve 10g of tannic acid in 100mL of anhydrous tetrahydrofuran, add 5mL of triethylamine, and slowly add 5mL of acryloyl chloride in an ice bath at 0-5℃. After the addition is complete, raise the temperature to room temperature and react for 5 hours. After the reaction is complete, filter to remove triethylamine hydrochloride, concentrate the filtrate and add deionized water to precipitate. The precipitate is dried under vacuum to obtain modified tannic acid.

[0028] (2) Bioleaching: Take a complex polymetallic tailings (containing 0.85% copper and 0.62% zinc) and add it to the reactor. Add leaching medium at a ratio of tailings mass to effective reactor volume of 1:5. Add 0.5% of the tailings mass of the dual-responsive disulfide bond-containing silane coupling agent prepared by S1 and mix evenly. Add Leptospira ironophilic bacterial solution to the reactor. The inoculum amount is 5% of the effective reactor volume, and the bacterial concentration is 1.5 × 10⁻⁶. 8 The concentration of modified tannic acid was increased to 100 mg / L and the leaching temperature was controlled at 35℃, the initial pH was 2.0, and the leaching cycle was 15 days, during which stirring was maintained.

[0029] S4. Leachate Treatment and Circulation After leaching, solid and liquid are separated. Copper is recovered from the leachate by solvent extraction. The raffinate is replenished with ferrous sulfate and ammonium sulfate and then returned to the reactor for recycling.

[0030] Leaching effect: The copper leaching rate reached 92.5% and the zinc leaching rate reached 90.1%, with the zinc leaching rate also significantly improved, indicating that the hierarchical electron transport network constructed in this invention also has a promoting effect on the oxidative dissolution of zinc sulfide minerals.

[0031] Example 2 This embodiment is basically the same as Embodiment 1, except that some key process parameters are used with boundary values ​​or different combinations to verify the stability and adaptability of the technical solution.

[0032] S1. Preparation of dual-responsive disulfide-bonded silane coupling agents (1) Dissolve 0.1 mol γ-mercaptopropyltrimethoxysilane in 100 mL of anhydrous ethanol, add 0.08 mol hydrogen peroxide (30% aqueous solution), and react at 25 °C for 20 hours to carry out oxidative coupling reaction; after the reaction is completed, remove the solvent by vacuum distillation to obtain the intermediate product.

[0033] (2) Dissolve 0.05 mol of the above intermediate product in 50 mL of anhydrous acetonitrile, add 0.08 mol of 4-dimethylaminopyridine, and slowly add 0.06 mol of tert-butyl chloride at 10 °C. After the addition is complete, raise the temperature to 25 °C and react for 6 hours. The post-treatment is the same as in Example 1 to obtain a dual-responsive silane coupling agent containing disulfide bonds.

[0034] S2. Construction of Immobilized Electron Mediator Filler (1) Disperse 1g of carboxylated multi-walled carbon nanotubes ultrasonically in 200mL of deionized water, add 1g of anthraquinone-2-sulfonate sodium, and stir to dissolve.

[0035] (2) Under nitrogen protection, the temperature was raised to 65°C, 1.2 g of ferric chloride was added, and the reaction was carried out for 8 hours.

[0036] (3) The post-treatment was the same as in Example 1 to obtain a carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material.

[0037] (4) The above composite material is mixed with porous carbon felt at a mass ratio of 1:5, loaded and placed in a reactor. The loading method is the same as in Example 1.

[0038] S3. Preparation and Leaching Operation of Modified Tannic Acid (1) Preparation of modified tannic acid: 10g of tannic acid was dissolved in 100mL of anhydrous tetrahydrofuran, 4mL of triethylamine was added, and 3mL of acryloyl chloride was slowly added dropwise in an ice bath at 0-5℃. After the addition was completed, the reaction was carried out at room temperature for 4 hours. The post-treatment was the same as in Example 1 to obtain modified tannic acid.

[0039] (2) Bioleaching: A dual-response disulfide-bonded silane coupling agent was added at 0.3% of the tailings mass. The inoculum amount of Leptospira ferrophila was 8% of the effective reactor volume, with a bacterial concentration of 1.2 × 10⁻⁶. 8 The modified tannic acid concentration was 180 mg / L; the leaching temperature was 32℃, the initial pH was 1.9, and the leaching period was 18 days.

[0040] S4. Leachate treatment and circulation are the same as in Example 1.

[0041] Leaching effect: The copper leaching rate reached 90.2% and the zinc leaching rate reached 87.0%. The passivation of the mineral surface was slight during the leaching process, and the immobilized electron mediator filler maintained good activity. The results show that under the parameter boundary conditions, the method of the present invention can still maintain excellent leaching performance and has good process adaptability.

[0042] Example 3 This embodiment is basically the same as Embodiment 1, except that several key process parameters adopt the boundary values ​​of the range defined in the claims to verify the feasibility of the technical solution under extreme conditions.

[0043] S1. Preparation of dual-responsive disulfide-bonded silane coupling agents (1) Dissolve 0.1 mol γ-mercaptopropyltrimethoxysilane in 100 mL of anhydrous ethanol, add 0.03 mol iodine, and react at 20 °C for 24 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain the intermediate product.

[0044] (2) Dissolve 0.05 mol of the above intermediate product in 50 mL of anhydrous chloroform, add 0.025 mol of triethylamine, and slowly add 0.04 mol of acetyl chloride at 0 °C. After the addition is complete, maintain the reaction at 0 °C for 8 hours. The post-treatment is the same as in Example 1 to obtain a dual-responsive silane coupling agent containing disulfide bonds.

[0045] S2. Construction of Immobilized Electron Mediator Filler (1) Disperse 1g of carboxylated multi-walled carbon nanotubes ultrasonically in 200mL of deionized water, add 1g of anthraquinone-2-sulfonate sodium, and stir to dissolve.

[0046] (2) Under nitrogen protection, the temperature was raised to 60°C, and ammonium persulfate was added in an equal molar amount to sodium anthraquinone-2-sulfonate. The reaction was carried out for 4 hours.

[0047] (3) The post-treatment was the same as in Example 1 to obtain a carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material.

[0048] (4) The above composite material is mixed with porous carbon felt at a mass ratio of 1:20, loaded and placed in a reactor. The loading method is the same as in Example 1.

[0049] S3. Preparation and Leaching Operation of Modified Tannic Acid (1) Preparation of modified tannic acid: 10g of tannic acid was dissolved in 100mL of anhydrous tetrahydrofuran, and triethylamine with a molar ratio of 1.0:1 to acryloyl chloride was added. Acryloyl chloride with a mass ratio of 1:3 to tannic acid was slowly added dropwise in an ice bath at 0-5℃. After the addition was completed, the reaction was carried out at room temperature for 6 hours. The post-treatment was the same as in Example 1 to obtain modified tannic acid.

[0050] (2) Bioleaching: A dual-response disulfide-bonded silane coupling agent was added at 0.5% of the tailings mass. The inoculum amount of Leptospira ferrophila was 2% of the effective reactor volume, with a bacterial concentration of 1.0 × 10⁻⁶. 8 The modified tannic acid concentration was 50 mg / L; the leaching temperature was 30℃, the initial pH was 1.8, and the leaching cycle was 20 days.

[0051] S4. Leachate treatment and circulation are the same as in Example 1.

[0052] Leaching effect: The copper leaching rate reached 87.0% and the zinc leaching rate reached 83.1%. Although the leaching rate was slightly lower than the preferred scheme of Example 1 under several boundary conditions, it was still significantly higher than that of traditional bioleaching methods (usually below 60%). Moreover, the formation of the passivation layer on the mineral surface was significantly suppressed during the leaching process, and the immobilized electron mediator filler remained intact. The results show that the technical solution of the present invention still has good leaching effect under various parameter boundary conditions, and the numerical range defined in the claims is technically reasonable.

[0053] Comparative Example 1 This comparative example is basically the same as Example 1, except that: no dual-responsive disulfide bond silane coupling agent is added in step S1, no immobilized electron mediator packing is placed in the reactor in step S2, no modified tannic acid is added in step S3, and the leaching process relies solely on the natural leaching action of Leptospira ironophila.

[0054] Leaching effect: The copper leaching rate was 52.1% and the zinc leaching rate was 55.3%. After leaching, the mineral surface was clearly covered with a yellowish-brown precipitate layer. Scanning electron microscopy revealed a dense sulfur film and iron alum crystal layer, indicating severe passivation.

[0055] Comparative Example 2 This comparative example is basically the same as Example 1, except that: no immobilized electron mediator packing is placed in the reactor in step S2; no modified tannic acid is added in step S3, and only a dual-responsive disulfide bond-containing silane coupling agent is added in step S1 (the amount added is the same as in Example 1).

[0056] Leaching effect: The copper leaching rate was 64.3% and the zinc leaching rate was 66.8%, which is an improvement compared with Comparative Example 1. The formation of sulfur film on the mineral surface was reduced, but local iron precipitation layers were still visible, indicating that the single coupling agent can partially inhibit the spread of sulfur film, but has limited effect on electron accumulation and iron precipitation.

[0057] Comparative Example 3 This comparative example is basically the same as Example 1, except that: no dual-responsive disulfide bond silane coupling agent is added in step S1; no modified tannic acid is added in step S3; and only immobilized electron mediator filler is set in step S2 (the preparation method is the same as in Example 1).

[0058] Leaching effect: The copper leaching rate was 58.7% and the zinc leaching rate was 60.1%. This is an improvement compared to Comparative Example 1, but there are still obvious sulfur films and iron precipitation layers on the mineral surface, indicating that although a single electron mediator can partially extract electrons, it cannot solve the problems of sulfur film spreading and iron ion hydrolysis precipitation.

[0059] Comparative Example 4 This comparative example is basically the same as Example 1, except that: no dual-responsive disulfide bond silane coupling agent is added in step S1; no immobilized electron mediator packing is placed in the reactor in step S2; and modified tannic acid is added only in step S3 (the amount added is the same as in Example 1).

[0060] Leaching effect: The copper leaching rate was 61.2% and the zinc leaching rate was 63.5%. This is an improvement over Comparative Example 1, and the iron precipitation on the mineral surface is significantly reduced. However, a sulfur film layer still exists, indicating that modified tannic acid alone can complex iron ions and inhibit iron precipitation, but its effect on the sulfur film problem is limited.

[0061] Comparative Example 5 This comparative example is basically the same as Example 1, except that: in step S1, unmodified γ-mercaptopropyltrimethoxysilane (KH-590) was used instead of the dual-responsive disulfide bond-containing silane coupling agent, and no disulfide bond construction or acylation modification was performed. The immobilized electron mediator filler in step S2 and the modified tannic acid in step S3 are the same as in Example 1.

[0062] Leaching effect: The copper leaching rate was 71.2% and the zinc leaching rate was 68.5%, which was significantly lower than that of Example 1 (copper 92.5%). This indicates that the ordinary silane coupling agent cannot release mercapto groups in response to changes in redox potential, and failed to react chemically with the modified tannic acid to build a functional network. The interface protection and anchoring functions are missing.

[0063] Comparative Example 6 This comparative example is basically the same as Example 1, except that: in step S2, multi-walled carbon nanotubes without grafted polyanthraquinone-2-sulfonic acid are used instead of carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material, and are directly loaded onto porous carbon felt as filler. The dual-responsive silane coupling agent in step S1 and the modified tannic acid in step S3 are the same as in Example 1.

[0064] Leaching effect: The copper leaching rate was 68.7% and the zinc leaching rate was 66.3%, which was significantly lower than that in Example 1. This indicates that ordinary carbon nanotubes lack polyanthraquinone-2-sulfonic acid electron mediators and cannot efficiently extract electrons released by the oxidation of sulfide minerals. The passivation phenomenon caused by electron accumulation still exists on the mineral surface.

[0065] Comparative Example 7 This comparative example is basically the same as Example 1, except that: in step S3, unmodified ordinary tannic acid is used instead of acryloyl-modified tannic acid, and the concentration is the same as in Example 1; the dual-responsive silane coupling agent in step S1 and the immobilized electron mediator filler in step S2 are the same as in Example 1.

[0066] Leaching effect: The copper leaching rate was 70.8% and the zinc leaching rate was 69.2%. This is significantly lower than that of Example 1, indicating that although ordinary tannic acid has a certain iron complexing ability, it lacks carbon-carbon double bonds and cannot react with the thiol groups released by the cleavage of the silane coupling agent to form a covalent anchor. As a result, the functional network construction fails and the synergistic effect cannot be exerted.

[0067] Comparative Example 8 This comparative example is basically the same as Example 1, except that modified tannic acid is not added in step S3, that is, only dual-responsive disulfide bond-containing silane coupling agent and immobilized electron mediator filler are used.

[0068] Leaching effect: The copper leaching rate was 76.8% and the zinc leaching rate was 73.5% according to the test results.

[0069] Results Analysis: Although the effect of this comparative example was better than that of using either component alone (Comparative Examples 2-4), it was still significantly lower than that of Example 1 (copper 92.5%), indicating that even with the simultaneous use of coupling agents and electron mediators, the passivation problem cannot be completely solved without the iron complexing function of modified tannic acid. Combined with the results of Comparative Examples 5-7, this further confirms the necessity of the synergistic effect of coupling agents, electron mediators, and modified tannic acid. To facilitate comparison of the technical effects of each embodiment and comparative example, the main results are summarized in Table 1 below: As shown in Table 1, the copper leaching rate of Example 1 of this invention reached 92.5%, which is significantly better than that of the comparative examples. After replacing the single component of comparative examples 5-7 with ordinary substances, the leaching rate dropped to about 70%, indicating that there is a significant synergistic effect among the dual-responsive disulfide bond-containing silane coupling agent, carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material, and modified tannic acid.

[0070] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0071] It should be understood that the disclosed apparatus can be implemented in other ways, as illustrated in the embodiments provided in this application. For example, the apparatus embodiments described above are merely illustrative; the division of units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or communication connections shown or discussed may be through some interfaces; the indirect coupling or communication connections between devices or units may be telecommunications or other forms.

[0072] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A method for resource leaching of complex polymetallic tailings based on in-situ microbial activation, characterized in that, Includes the following steps: S1. The tailings are mixed with a dual-responsive silane coupling agent containing disulfide bonds, so that the coupling agent forms coordination bonds with the metal atoms on the surface of the sulfide ore through its mercapto groups, thereby forming a sacrificial interface layer on the surface of the sulfide ore. S2. Carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material was loaded onto a porous support and placed in a bioleaching reactor as an immobilized electron mediator filler. S3. Add Leptospira ferrophila bacterial solution to the reactor, and add modified tannic acid containing carbon-carbon double bonds obtained by reacting tannic acid with acryloyl chloride, and carry out bioleaching; S4. Solid-liquid separation: the leaching solution recovers the target metal, and the raffinate is recycled.

2. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 1, characterized in that, The preparation method of the dual-responsive disulfide bond-containing silane coupling agent is as follows: (a) Dissolve γ-mercaptopropyltrimethoxysilane in anhydrous ethanol, add an oxidant to carry out an oxidative coupling reaction at a temperature of 20-40°C for 6-24 hours, remove the solvent by vacuum distillation to obtain the intermediate product. (b) Dissolve the intermediate product in an anhydrous organic solvent, add an acylation reagent and a base, react at 0-30°C for 2-8 hours, wash, dry, and concentrate under reduced pressure to obtain a dual-responsive silane coupling agent containing disulfide bonds.

3. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 2, characterized in that, In step (a), the molar ratio of γ-mercaptopropyltrimethoxysilane to the oxidant is 1:0.3-1:0.8, and the oxidant is elemental iodine or hydrogen peroxide.

4. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 2, characterized in that, In step (b), the molar ratio of the intermediate product to the acylation reagent is 1:0.8-1:1.5, and the molar ratio of the intermediate product to the base is 1:0.5-1:2; the acylation reagent is acetyl chloride or tert-butyl chloride, the base is triethylamine, pyridine or 4-dimethylaminopyridine, and the anhydrous organic solvent is dichloromethane, trichloromethane, acetonitrile or tetrahydrofuran.

5. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 1, characterized in that, The preparation method of the carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material is as follows: (1) Carboxylated multi-walled carbon nanotubes were ultrasonically dispersed in water, and sodium anthraquinone-2-sulfonate was added and stirred to dissolve; (2) Under nitrogen protection, heat to 60-80℃, add oxidant, and react for 4-8 hours; (3) The product was centrifuged, washed and dried to obtain carbon nanotube grafted polyanthraquinone-2-sulfonic acid composite material.

6. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 5, characterized in that, The mass ratio of the carboxylated multi-walled carbon nanotubes to sodium anthraquinone-2-sulfonate is 1:1 to 1:3, the oxidant is ammonium persulfate or ferric chloride, and the molar ratio of the oxidant to sodium anthraquinone-2-sulfonate is 1:1 to 2:

1.

7. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 1, characterized in that, The modified tannic acid is added at a concentration of 50-200 mg / L, and its preparation method is as follows: tannic acid is dissolved in anhydrous tetrahydrofuran, and triethylamine is added as an acid-binding agent, wherein the molar ratio of triethylamine to acryloyl chloride is 1.0:1~1.5:

1. Acryloyl chloride is added dropwise in an ice bath at 0-5℃, and the reaction is carried out at room temperature for 4-6 hours. The mixture is then filtered, concentrated, precipitated, and dried to obtain modified tannic acid; wherein the mass ratio of acryloyl chloride to tannic acid is 1:3 to 1:

1.

8. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 1, characterized in that, In step S3, the temperature for bioleaching is 30-40℃, the initial pH is 1.8-2.2, and the leaching cycle is 10-20 days.

9. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 1, characterized in that, The porous carrier is a porous carbon felt, and the mass ratio of the carbon nanotube-grafted polyanthraquinone-2-sulfonic acid composite material to the porous carbon felt is 1:5-1:

20.

10. The method for resource leaching of complex polymetallic tailings based on in-situ microbial activation as described in claim 1, characterized in that, The inoculation amount of the Leptospira ironophila bacterial suspension is 2%-10% of the effective volume of the reactor, and the bacterial concentration is ≥1×10⁻⁶. 8 cells / mL.

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