A method for promoting chalcopyrite bioleaching by in-situ depassivation

Abstract

The present invention belongs to the field of resources and environment, and discloses a method for promoting chalcopyrite bioleaching by in-situ depassivation: in an anaerobic environment, passivated chalcopyrite and reduced sulfur are added to a 9K culture medium, an acidophilic microbial strain is inoculated for culture, and the chalcopyrite is collected by centrifugation; the collected chalcopyrite is dried and added to a 9K culture medium, and the acidophilic microbial strain is inoculated for culture and leaching under an aerobic environment. The present invention introduces acidophilic microorganisms and sulfur into the anaerobic system, so that the dense passivation film of the chalcopyrite can be reduced and removed, allowing the copper ions in the mineral to be leached under aerobic conditions in the later stage. This not only overcomes the shortcomings of pure chemical reaction leaching, such as high energy consumption, high consumables, and environmental pollution, but also solves the problem of low utilization efficiency due to the passivation film hindering leaching during the bioleaching process, so that the chalcopyrite can be utilized to the greatest extent. This in-situ depassivation bioleaching technology has a wide range of applications, low site requirements, and can be used on a large scale industrially.

Description

Technical Field

[0001] The invention belongs to the field of resources and environment, and in particular relates to a method for promoting chalcopyrite bioleaching by in-situ depassivation. Background Art

[0002] my country is rich in chalcopyrite (CuFeS2), but small and medium-sized, low-grade deposits predominate. Previous pyrometallurgical processes have significant pollution risks, high reagent consumption, and relatively high energy consumption. Consequently, bioleaching technologies for low-grade ores, offering advantages such as simple operation, low energy consumption, low cost, and environmental friendliness, have become a research hotspot. Bioleaching extracts valuable metals through the interaction of acidophilic microorganisms with minerals. These microorganisms utilize minerals as energy sources through direct, indirect, and combined pathways, oxidizing and decomposing sulfide ores to ultimately yield copper products. Therefore, enhancing the interaction between microorganisms and minerals is an important approach to improving chalcopyrite bioleaching efficiency.

[0003] Researchers have used a variety of methods to directly or indirectly improve the efficiency of bacterial-mineral interactions in chalcopyrite bioleaching systems. The following mainstream approaches exist: adding associated minerals during leaching, or utilizing ions released by the minerals themselves to influence the system's redox potential; enhancing the galvanic cell effect between minerals; and optimizing the structure of acidophilic microbial communities—selecting and compounding communities with high leaching rates based on the oxidation capacity of different strains. However, microbial leaching has a bottleneck—passivation during the leaching process, resulting in low leaching rates, which has long limited the application and development of bacterial copper leaching. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a method for promoting chalcopyrite bioleaching by in-situ depassivation.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A method for promoting chalcopyrite bioleaching by in-situ depassivation comprises the following steps:

[0007] (1) In an anaerobic environment, passivated chalcopyrite and reduced sulfur were added to 9K culture medium, acidophilic microbial strains were inoculated for cultivation, and the chalcopyrite was collected by centrifugation;

[0008] (2) The collected chalcopyrite was dried and added to 9K culture medium, inoculated with acidophilic microbial strains under an aerobic environment, cultured and leached.

[0009] In the above-mentioned in-situ depassivation method for promoting chalcopyrite bioleaching, preferably, in step (1), the amount of passivated chalcopyrite added is 1wt%-20wt% of the culture medium, and the reduced sulfur is calculated as elemental sulfur, and the sulfur element is added to make its concentration in the culture medium reach 0.5g-10g / L; the inoculum size of the acidophilic microbial strain is 1.0×10 6 -1×10 9 pieces / mL.

[0010] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (1), the initial pH of the 9K culture medium is 1.5-3.0, the culture temperature is 25-35°C, the shaker speed during the culture process is 100-250 rpm, and the culture time is 6-25 days.

[0011] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (1), when the concentration of copper ions in the culture medium is measured to reach 800-1200 mg / L, the culture is stopped.

[0012] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (1), the reduced sulfur is at least one of elemental sulfur, sodium sulfide, sodium sulfite, and sodium thiosulfate;

[0013] The acidophilic microbial strain is selected from Thiobacillus ferrooxidans (Acidithiobacillus ferrooxidans) , Leptospirillum ferrooxidans (Leptospirillum ferrooxidans) , Leptospirillum ferroferatum (Leptospirillum ferriphilum) , Thiobacillus thiooxidans (Acidithiobacillus thiooxidans) , Bacillus thermooxidans (Sulfobacillus thermosulfidooxidans) , Thermophilic Acidithiobacillus (Acidithiobacillus caldus) , Sulfolobus metallurgica (sulfolobus metallicus) One of them.

[0014] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (1), during the cultivation process, a non-oxygen stable gas is regularly added to the anaerobic environment system to maintain the anaerobic environment.

[0015] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (2), the initial pH of the 9K culture medium is 1.5-3.0, the culture temperature is 25-35°C, the shaker speed during the culture process is 100-250 rpm, and the culture time is 5-25 days.

[0016] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (2), the amount of the collected chalcopyrite added is 1wt%-20wt% of the culture medium; the inoculation amount of the acidophilic microbial strain is 1×10 6 -1×10 9pieces / mL.

[0017] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (1), the acidophilic microbial strain is first cultured to the logarithmic growth phase and then collected and added to an anaerobic environment.

[0018] In the above-mentioned method for promoting chalcopyrite bioleaching by in-situ depassivation, preferably, in step (2), the aerobic environment refers to an oxygen concentration not lower than the oxygen concentration in the atmosphere.

[0019] The surface passivation of chalcopyrite contains substances such as jarosite, elemental sulfur, and polysulfides. The generation of mineral surface passivation during the leaching process is a key factor in inhibiting the bioleaching rate. The present invention adjusts the dissolved oxygen concentration in the chalcopyrite bioleaching system with a low copper leaching rate, switches to anaerobic conditions, and then adds low-valent sulfur substances to the system. Under these conditions, the large iron-sulfur oxidation function of the acidophilic leaching microorganisms is converted into iron reduction and sulfur oxidation functions, and the Fe in the mineral surface passivation is reduced. 3+ Reduction to Fe 2 + , dissolving and destroying the passivation film, the depassivated chalcopyrite is returned to the leaching stage in an aerobic environment, and efficient copper leaching can be achieved again.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention introduces acidophilic microorganisms and sulfur into an anaerobic system, enabling the reduction and removal of the dense passivation film on chalcopyrite, allowing copper ions in the mineral to continue leaching under later aerobic conditions. This not only overcomes the shortcomings of purely chemical reaction leaching, which are energy-intensive, material-intensive, and environmentally polluting, but also addresses the low utilization efficiency of the bioleaching process due to the passivation film hindering leaching, thereby maximizing the utilization of chalcopyrite. This in-situ depassivation bioleaching technology has a wide range of applications, requires minimal site requirements, and is suitable for large-scale industrial application.

[0022] In summary, the present invention regulates key metabolic pathways such as Fe / S / Cu in the bacteria-mineral interaction system by controlling the dissolved oxygen content in the leaching system, thereby affecting the growth and ablation process of the passivation layer on the mineral surface, and utilizes anaerobic iron-reducing acidophilic microorganisms to achieve in situ removal of the passivation layer on the mineral surface during chalcopyrite bioleaching, providing new ideas for the development of low-cost, pollution-free copper leaching enhancement technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1These are the EDS surface scans of the passivated chalcopyrite used in the embodiments of the present invention: a is an image of the passivated chalcopyrite, b is a surface scan of the O element in the passivated chalcopyrite, c is a surface scan of the K element in the passivated chalcopyrite, d is a surface scan of the S element in the passivated chalcopyrite, e is a surface scan of the Fe element in the passivated chalcopyrite, and f is a surface scan of the Cu element in the passivated chalcopyrite.

[0024] Figure 2 This is a diagram of ferrous ion generation in the depassivation experimental system using elemental sulfur in Example 1 of the present invention.

[0025] Figure 3 This is a diagram of ferrous ion generation in the sodium thiosulfate depassivation experimental system in Example 2 of the present invention.

[0026] Figure 4 This is a diagram of ferrous ion generation in the sodium thiosulfate depassivation experimental system in Example 3 of the present invention.

[0027] Figure 5 This is a comparison chart of leaching of passivated copper ore and leaching of depassivated copper in Example 1 of the present invention.

[0028] Figure 6 This is a comparison chart of leaching with passivated copper ore and leaching with depassivated copper in Example 2 of the present invention.

[0029] Figure 7 is the potassium ion concentration in the system during the anaerobic experiment in Example 2 of the present invention.

[0030] Figure 8 These are three ion concentrations at different stages in Example 2 of the present invention: A is the first stage passivation experiment, B is the second stage anaerobic depassivation experiment, and C is the third stage aerobic bioleaching experiment. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0032] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0033] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0034] The EDS scans of the passivated chalcopyrite used in Examples 1, 2, and 3 below are shown in FIG. Figure 1As shown in the figure, it can be seen that there is a layer on the surface of chalcopyrite that is rich in K, O, and S elements, namely the passivation layer jarosite.

[0035] Example 1:

[0036] A method for promoting chalcopyrite bioleaching by in-situ depassivation comprises the following steps:

[0037] (1) Acidithiobacillus ferrooxidans (Acidithiobacillus ferrooxidans) Expand the culture: Acidithiobacillus ferrooxidans (Acidithiobacillus ferrooxidans) The culture was expanded in 9K medium with an initial pH of 2.0, a culture temperature of 30°C, and a shaker speed of 170 rpm. The culture was filtered to separate the solid and liquid, and the bacterial liquid was collected by centrifugation at a speed of 9000 rpm for 20 min.

[0038] (2) Chalcopyrite biopassivation experiment: The experiment was carried out in a 500 mL conical flask containing 198 mL of sterile deionized water, 2 mL of concentrated Acidithiobacillus ferrooxidans culture without metabolites, and 4 g of chalcopyrite sample. The initial pH was adjusted to 2.0 with 0.1 mol / L sulfuric acid, and the initial bacterial concentration was 4 × 10 8 To promote surface passivation, namely the formation of jarosite (KFe3(SO4)2(OH)6), 2.224g FeSO4·7H2O and 0.23g K2SO4 were added, based on the ratio of iron to potassium in jarosite. The incubation temperature was 30°C, with a shaker speed of 170 rpm, for 3 days. The passivated chalcopyrite was collected by wet sieving and dried in a vacuum oven.

[0039] (3) Anaerobic experiment: Prepare an anaerobic bottle, fill it with 100 mL of 9K culture medium, add passivated chalcopyrite and S powder, and inoculate the Acidithiobacillus ferrooxidans cultured in step (1). (Acidithiobacillus ferrooxidans) The inoculum size was 4×10 8 / mL, where the concentration of passivated chalcopyrite is 1wt%, and the amount of S powder added is 0.2g, that is, the sulfur concentration in the culture medium is 2g / L; N2 / CO2 gas is regularly added to the system during the anaerobic process to maintain the anaerobic environment, and the culture is carried out for 25 days; the copper ion, ferrous ion, and total iron content are monitored every 24h. The ion parameter monitoring results are shown in Tables 1-3, and the ferrous ion generation results are shown in Figure 2Tables 1-3 show the ion parameters in the liquid measured in three parallel groups. Under anaerobic conditions, Acidithiobacillus ferrooxidans uses elemental sulfur as an electron donor to reduce the ferric iron in jarosite to ferrous iron, resulting in a gradual increase in the concentration of ferrous iron ions over time. Jarosite gradually dissolves over time, converting the solid-phase iron therein to ferrous iron ions, leading to an increase in the total iron concentration in the solution. As the jarosite passivation layer gradually dissolves, exposing chalcopyrite, the microorganisms continue to react with the chalcopyrite, dissolving metallic copper, leading to a gradual increase in the copper ion concentration. Figure 2 The figure shows the change of ferrous ion concentration in the anaerobic system solution over time, which shows a continuous increasing trend, indicating that the jarosite on the surface of chalcopyrite gradually dissolves and the trivalent iron in the jarosite is reduced to ferrous ions and enters the solution.

[0040] Table 1 Ferrous iron concentration in the system (mg / L)

[0041]

[0042] Table 2 Total iron concentration in the system (mg / L)

[0043]

[0044] Table 3 Copper ion concentration in the system (mg / L)

[0045]

[0046] (4) Collecting chalcopyrite after the passivation layer is ablated: When the concentration of copper ions in the culture medium reaches 250 mg / L, collect the chalcopyrite by centrifugation and place it in a vacuum freeze-drying box for drying.

[0047] (5) Aerobic leaching of the passivation group: The passivated chalcopyrite collected after drying in step (2) was added to 100 mL of 9K culture medium at a concentration of 1 wt %, the leaching gas environment was atmospheric environment, and the Acidithiobacillus ferrooxidans was inoculated. (Acidithiobacillus ferrooxidans) The inoculum size was 4×10 7 The initial pH of the 9K medium was 2.0, the culture temperature was 30°C, the shaker speed was 170 rpm, and the culture was carried out for 25 days. Samples were taken every three days to determine the copper ion concentration.

[0048] Aerobic leaching of the depassivation group: the depassivated chalcopyrite collected after drying in step (4) was added to 100 mL of 9K culture medium at a concentration of 1 wt %, the leaching gas environment was atmospheric environment, and the Acidithiobacillus ferrooxidans was inoculated. (Acidithiobacillus ferrooxidans) The inoculum size was 4×10 7The initial pH of the 9K culture medium was 2.0, the culture temperature was 30°C, the shaker speed was 170 rpm, and samples were taken every three days to measure the copper ion concentration. After 15 days of culture, the copper ion concentration increased significantly. The copper ion monitoring data are shown in Table 4. Because the passivation layer formed on the surface of the chalcopyrite in the passivation group hindered the leaching of copper, the copper ion leaching of the three parallel groups of the passivation group was very slow and the leaching rate was very low. In the depassivation group, the leaching rate gradually increased with time, and the leaching rate was 6 times that of the passivated chalcopyrite, indicating that the passivation layer on the chalcopyrite surface was gradually dissolved.

[0049] The comparison chart of passivated copper leaching and depassivated copper leaching is as follows: Figure 5 As shown in the figure, the copper ion concentration curve of the passivation group is flat and there is no significant increase. The copper ion concentration curve of the depassivation group shows an upward trend and reaches the highest leaching rate at about 15 days.

[0050] Table 4 Copper ion leaching concentration of passivated ore and depassivated ore in aerobic experiment

[0051]

[0052] Example 2:

[0053] A method for promoting chalcopyrite bioleaching by in-situ depassivation comprises the following steps:

[0054] (1) Acidithiobacillus ferrooxidans (Acidithiobacillus ferrooxidans) Expand the culture: Acidithiobacillus ferrooxidans (Acidithiobacillus ferrooxidans) The culture was expanded in 9K medium with an initial pH of 2.0, a culture temperature of 30°C, and a shaker speed of 170 rpm. The culture was filtered to separate the solid and liquid, and the bacterial liquid was collected by centrifugation at a speed of 9000 rpm for 20 min.

[0055] (2) Chalcopyrite biopassivation experiment: The experiment was carried out in a 500 mL conical flask containing 198 mL of sterile deionized water, 2 mL of concentrated Acidithiobacillus ferrooxidans culture without metabolites, and 4 g of chalcopyrite sample. The initial pH was adjusted to 2.0 with 0.1 mol / L sulfuric acid, and the initial bacterial concentration was 4 × 10 8 To promote the formation of jarosite (KFe3(SO4)2(OH)6), 2.224g FeSO4·7H2O and 0.23g K2SO4 were added, based on the ratio of iron to potassium in jarosite. The incubation temperature was 30°C, with a shaker speed of 170 rpm, for 3 days. The passivated chalcopyrite was collected by wet sieving and dried in a vacuum oven.

[0056] (3) Anaerobic experiment: Prepare an anaerobic bottle, fill it with 100 mL of 9K culture medium, add passivated chalcopyrite and Na2SO3, and inoculate the Acidithiobacillus ferrooxidans cultured in step (1). (Acidithiobacillus ferrooxidans) The inoculum size was 4×10 8 The concentration of chalcopyrite was 1 wt%, the dosage of Na2SO3 was 0.7875 g, and N2 / CO2 gas was added to the system regularly to maintain the anaerobic environment during the anaerobic process. The culture was carried out for 25 days. The contents of copper ions, ferrous ions, and total iron were monitored every 24 hours. The results of ion parameter monitoring are shown in Tables 5 to 7. The results of ferrous ion generation are shown in Table 7. Figure 3 Tables 5-7 show the ion parameters in the liquid measured in three parallel groups. Under anaerobic conditions, Acidithiobacillus ferrooxidans uses Na2SO3 as an electron donor to reduce the ferric iron in jarosite to ferrous iron, so the ferrous ion concentration gradually increases over time. Jarosite gradually dissolves over time, and the solid-phase iron therein is converted to ferrous ions, so the total iron concentration in the solution also increases over time. As the jarosite passivation layer gradually dissolves, exposing chalcopyrite, the microorganisms continue to react with the chalcopyrite, dissolving metallic copper, so the copper ion concentration also gradually increases. Figure 3 The figure shows the change of ferrous ion concentration in the anaerobic system solution over time, which shows a continuous increasing trend, indicating that the jarosite on the surface of chalcopyrite gradually dissolves and the trivalent iron in the jarosite is reduced to ferrous ions and enters the solution.

[0057] Table 5 Ferrous iron concentration in the system (mg / L)

[0058]

[0059] Table 6 Total iron concentration in the system (mg / L)

[0060]

[0061] Table 7 Copper ion concentration in the system (mg / L)

[0062]

[0063] (4) Collecting chalcopyrite after the passivation layer is ablated: When the concentration of copper ions in the culture medium reaches 250 mg / L, collect the chalcopyrite by centrifugation and place it in a vacuum freeze-drying box for drying.

[0064] (5) Aerobic leaching of the passivation group: The passivated chalcopyrite collected after drying in step (2) was added to 300 mL of 9K culture medium at a concentration of 1 wt %, the leaching gas environment was atmospheric environment, and the acidophilic thiobacillus ferrooxidans was inoculated. (Acidithiobacillus Ferrooxidans) The inoculum size was 4×10 8The initial pH of the 9K medium was 2.0, the culture temperature was 30°C, and the shaker speed was 170 rpm. The culture was continued for 25 days. Samples were taken every three days to determine the copper ion concentration.

[0065] Aerobic leaching of the depassivation group: the chalcopyrite collected after drying in step (4) was added to 300 mL of 9K medium at a concentration of 1 wt %, the leaching gas environment was atmospheric environment, and the acidophilic thiobacillus ferrooxidans was inoculated. (Acidithiobacillus Ferrooxidans) The inoculum size was 4×10 8 The initial pH of the 9K medium was 2.0, the culture temperature was 30°C, and the shaker speed was 170 rpm. After 15 days of culture, the copper ion concentration increased significantly, as shown in Table 8.

[0066] Table 8 Copper ion leaching concentration

[0067]

[0068] In this example, the leaching of passivated copper ore and the leaching of depassivated copper were compared. Figure 6 As shown in the figure, compared with the passivated ore copper leaching, the depassivated copper leaching effect is more significant and can increase the copper leaching efficiency by 25%.

[0069] Figure 7 This is the potassium ion concentration in the system detected by the solution every three days in the anaerobic experiment of this embodiment. The dissolution rate of jarosite can reach 80.12%.

[0070] Figure 8 are three key ions (Cu 2+ 、Fe 2+ 、SO4 2- ) concentration test results, the first stage of the passivation experiment (the concentration of dissolved oxygen is 3-9mg / L) SO4 2- Continuously reducing, and SO4 2- Participate in the synthesis of jarosite corresponding to the second stage of anaerobic depassivation test (dissolved oxygen concentration is 0.1-0.3mg / L) SO4 2- As time goes by, the amount of jarosite on the surface of chalcopyrite gradually increases, which corresponds to the dissolution of jarosite on the surface of chalcopyrite, releasing sulfate into the solution and passivating the initial SO4 2- The concentration is almost the same as the SO4 released at the end of anaerobic 2- The concentration remains constant, proving that jarosite is almost completely dissolved. 2+ and Fe 2+ In the first two stages of the experimental system, the concentration was low, and in the third stage, the aerobic bioleaching (the concentration of dissolved oxygen was 3-9 mg / L) increased significantly, indicating that the leaching rate was improved. 2-In the first stage of the passivation experiment, the concentration of SO4 gradually decreased because it participated in the synthesis of the chalcopyrite surface passivation layer. In the second stage of the anaerobic depassivation experiment, the chalcopyrite surface passivation layer gradually dissolved, so SO4 2- The concentration gradually increases. In the third stage of aerobic bioleaching, the negative divalent sulfur in chalcopyrite will be oxidized to SO4 during the bioleaching process. 2- , so the concentration gradually increases. It can be seen from the figure that compared with the passivation stage and the depassivation stage, the Cu 2+ concentration and Fe 2+ The significant increase in concentration proves that the chalcopyrite leaching rate has been significantly enhanced.

[0071] Example 3:

[0072] A method for promoting chalcopyrite bioleaching by in-situ depassivation comprises the following steps:

[0073] (1) Acidithiobacillus ferrooxidans (Acidithiobacillus ferrooxidans) Expand the culture: Acidithiobacillus ferrooxidans (Acidithiobacillus ferrooxidans) The culture was expanded in 9K medium with an initial pH of 2.0, a culture temperature of 30°C, and a shaker speed of 170 rpm. The culture was filtered to separate the solid and liquid, and the bacterial liquid was collected by centrifugation at a speed of 9000 rpm for 20 min.

[0074] (2) Chalcopyrite biopassivation experiment: The experiment was carried out in a 500 mL conical flask containing 198 mL of sterile deionized water, 2 mL of concentrated Acidithiobacillus ferrooxidans culture without metabolites, and 4 g of chalcopyrite sample. The initial pH was adjusted to 2.0 with 0.1 mol / L sulfuric acid, and the initial bacterial concentration was 4 × 10 8 To promote the formation of jarosite (KFe3(SO4)2(OH)6), 2.224g FeSO4·7H2O and 0.23g K2SO4 were added, based on the ratio of iron to potassium in jarosite. The incubation temperature was 30°C, with a shaker speed of 170 rpm, for 3 days. The passivated chalcopyrite was collected by wet sieving and dried in a vacuum oven.

[0075] (3) Anaerobic experiment: Prepare an anaerobic bottle, fill it with 100 mL of 9K culture medium, add passivated chalcopyrite and Na2SO3, and inoculate the Acidithiobacillus ferrooxidans cultured in step (1). (Acidithiobacillus ferrooxidans) The inoculum size was 4×10 8 / mL, where the concentration of passivated chalcopyrite was 1wt% and the dosage of Na2S2O3 was 0.4938g; during the anaerobic process, N2 / CO2 gas was regularly added to the system to maintain the anaerobic environment, and the culture was carried out for 25 days; the content of copper ions, ferrous ions, and total iron was monitored every 24 hours. The results of ion parameter monitoring are shown in Tables 9-11, and the results of ferrous ion generation are shown in Tables 9-11. Figure 4 Tables 9-11 show the ion parameters in the liquid measured by three parallel groups. Under anaerobic conditions, Acidithiobacillus ferrooxidans uses Na2S2O3 as an electron donor to reduce the ferric iron in jarosite to ferrous iron, so the ferrous ion concentration gradually increases over time. Jarosite gradually dissolves over time, and the solid-phase iron therein is converted to ferrous ions, so the total iron concentration in the solution also increases over time. As the jarosite passivation layer gradually dissolves, exposing chalcopyrite, the microorganisms continue to react with the chalcopyrite, dissolving metallic copper, so the copper ion concentration also gradually increases. Figure 4 The figure shows the change of ferrous ion concentration in the anaerobic system solution over time, which shows a continuous increasing trend, indicating that the jarosite on the surface of chalcopyrite gradually dissolves and the trivalent iron in the jarosite is reduced to ferrous ions and enters the solution.

[0076] Table 9 Ferrous iron concentration in the system (mg / L)

[0077]

[0078] Table 10 Total iron concentration in the system (mg / L)

[0079]

[0080] Table 11 Copper concentration in the system (mg / L)

[0081]

[0082] (4) Collecting chalcopyrite after the passivation layer is ablated: When the concentration of copper ions in the system reaches 250 mg / L, collect the chalcopyrite by centrifugation and place it in a vacuum freeze-drying box for drying.

[0083] (5) Aerobic leaching: The chalcopyrite collected after drying in step (4) was added to 100 mL of 9K culture medium at a concentration of 1 wt %, the leaching gas environment was atmospheric environment, and the chalcopyrite was inoculated with Acidithiobacillus ferrooxidans. (Acidithiobacillus ferrooxidans) The inoculum size was 4×10 7 / mL, the initial pH of 9K culture medium was 2.0, the culture temperature was 30°C, the shaker speed was 170 rpm, and after 15 days of culture, the copper ion concentration increased significantly, as shown in Table 12.

[0084] Table 12 Copper ion leaching concentration

[0085]

[0086] The above is only a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiment. For those skilled in the art, improvements and modifications obtained without departing from the technical concept of the present invention should also be considered as the scope of protection of the present invention.

Claims

1. A method for promoting chalcopyrite bioleaching by in-situ depassivation, characterized in that: The following steps are involved: (1) In an anaerobic environment, passivated chalcopyrite and reduced sulfur were added to 9K culture medium, and acidophilic microbial strains were inoculated for cultivation. When the copper ion concentration in the culture medium reached 250 mg / L, the chalcopyrite was collected by centrifugation. The amount of passivated chalcopyrite added was 1 wt%-20 wt% of the culture medium, and the reduced sulfur was calculated as elemental sulfur. The sulfur element was added to make its concentration in the culture medium reach 0.5 g-10 g / L. The inoculation amount of the acidophilic microbial strain was 1.0 × 10 6 -1×10 9 / mL; the acidophilic microbial strain is selected from Thiobacillus ferrooxidans (Acidithiobacillus ferrooxidans); (2) The collected chalcopyrite is dried and added to 9K culture medium, and acidophilic microbial strains are inoculated under an aerobic environment for cultivation and leaching. The acidophilic microbial strains are selected from Thiobacillus ferrooxidans. (Acidithiobacillus ferrooxidans) .

2. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, characterized in that: In step (1), the initial pH of the 9K culture medium is 1.5-3.0, the culture temperature is 25-35°C, the shaker speed during the culture process is 100-250 rpm, and the culture time is 6-25 days.

3. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, characterized in that: In step (2), when the concentration of copper ions in the culture medium is measured to be 800-1200 mg / L, the culture is stopped.

4. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, wherein: In step (1), the reduced sulfur is at least one of elemental sulfur, sodium sulfide, sodium sulfite, and sodium thiosulfate.

5. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, wherein: In step (1), during the culture process, a non-oxygen stable gas is regularly added to the anaerobic environment system to maintain the anaerobic environment.

6. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, characterized in that: In step (2), the initial pH of the 9K culture medium is 1.5-3.0, the culture temperature is 25-35°C, the shaker speed during the culture process is 100-250 rpm, and the culture time is 5-25 days.

7. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, wherein: In step (2), the amount of chalcopyrite collected is 1wt%-20wt% of the culture medium; the amount of acidophilic microbial strain inoculated is 1×10 6 -1×10 9 pieces / mL.

8. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, characterized in that: In step (1), the acidophilic microbial strain is first cultured to the logarithmic growth phase and then collected and added to an anaerobic environment.

9. The method for promoting chalcopyrite bioleaching by in-situ depassivation according to claim 1, wherein: In step (2), the aerobic environment refers to an oxygen concentration not lower than the oxygen concentration in the atmosphere.

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