Composite ore leaching flora and application thereof in biological metallurgy

Abstract

According to the efficient composite ore leaching flora and the application thereof, by optimizing the specific proportion of thiobacillus ferrooxidans, thiobacillus acidophilus, thiobacillus thiooxidans and high-temperature-resistant leptospirillum and combining a directional domestication technology, the tolerance of the flora to ores with high toxicity and complex components is remarkably improved. Extracellular polymeric substances secreted by the flora strengthen mineral surface reaction through chelation, and the copper leaching rate is increased by 40% or above compared with that of a single strain in cooperation with a segmented temperature control process. The flora provided by the invention can realize efficient metal recovery under the condition of low energy consumption, is suitable for large-scale dump leaching and reactor leaching, and has dual advantages of environmental protection and economy.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial metallurgy, and in particular relates to a high-efficiency composite leaching bacterial community and application thereof in biological leaching of sulfide ores. Background Art

[0002] Traditional biometallurgical technology relies on the metabolic activity of a single functional strain (such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans, etc.), which has significant limitations:

[0003] Poor environmental adaptability: A single bacterial species has a narrow metabolic pathway and is difficult to cope with complex mineral components. 2+ When the concentration is >5g / L, the Fe 2+ The oxidase activity is inhibited by more than 70% (Reference: Rawlings et al., 2003), and As in arsenic-containing minerals (such as arsenopyrite) 3+ Concentrations > 1g / L can cause bacterial DNA damage, resulting in a 50%-80% decrease in leaching efficiency.

[0004] Long leaching cycle: Single bacteria system due to sulfur oxidation intermediates (such as elemental sulfur S 0 ) accumulates and easily forms a passivation layer on the mineral surface. Studies have shown that in chalcopyrite leaching, a single strain of bacteria takes 25-35 days to reach an 80% copper leaching rate, and the reaction rate in the later stage drops to less than 10% of the initial value (Reference: Pradhan et al., 2008).

[0005] Insufficient thermal stability: The optimum temperature for most leaching bacteria is 30-35°C. When the temperature of the ore pile is >45°C (such as deep ore bodies or tropical areas), the rate of bacterial protein denaturation accelerates and the ATP synthesis efficiency decreases by 60%-90%, causing the leaching process to stagnate.

[0006] Although the existing composite bacterial community technology attempts to break through the above limitations by combining multiple bacterial species (such as iron oxidizing bacteria + sulfur oxidizing bacteria), it still has the following bottlenecks:

[0007] Interbacterial competition inhibition: Different bacterial species in a mixed bacterial community have different 2+ , S 0 ) leads to metabolic imbalance. For example, when Thiobacillus ferrooxidans and Leptospirillum coexist, the two have a strong competition for Fe 2+ Competition from the bacteria makes the total oxidation rate lower than that of a single bacterial species. In addition, metabolic byproducts (such as H + , organic acids) further aggravates the community instability.

[0008] The function of extracellular polymeric substances (EPS) is not directionally regulated: Most of the existing technologies rely on the spontaneous secretion of EPS by the microbial community, with random components and single functions. For example, the density of metal chelating functional groups in wild-type microbial EPS is usually only 2 - 4 mmol / g, and when the polysaccharide proportion > 70%, it is easy to form a viscous barrier, hindering the contact between bacteria and minerals.

[0009] Lack of dynamic response: Traditional process parameters (temperature, pH, redox potential) are mostly statically controlled and cannot adapt to the phased requirements of mineral leaching. For example, in the initial stage of leaching, promoting microbial attachment (low temperature and high oxygen) is required, and in the middle stage, strengthening sulfur oxidation (high temperature and low oxygen) is needed. However, the existing technologies lack a real-time feedback mechanism, resulting in a 20% - 30% increase in energy consumption.

[0010] Aiming at the problems of poor adaptability of single strains, long leaching cycle, and low high-temperature activity in traditional biohydrometallurgy technologies, as well as the defects of inter-bacterial competition inhibition, non-directional regulation of the function of extracellular polymeric substances (EPS), and lack of dynamic response mechanism in existing composite microbial communities, the present invention provides a composite ore-leaching microbial community and its synergistic application system. By optimizing the strain ratio (Acidithiobacillus ferrooxidans 30 - 45%, Acidithiobacillus thiooxidans 20 - 35%, Sulfurimonas oxidans 15 - 25%, Leptospirillum ferriphilum 10 - 20%) and directional domestication strategies (gradient toxicity, potential switching, ultrasonic stress), combined with genetic engineering to enhance the stress resistance of strains (the arsenic efflux efficiency is increased by 5 times, and the sulfur oxidation rate is increased by 300%), decoupling of metabolic pathways (Fe 2+ / S 0 time-sharing oxidation) and intelligent control systems (Raman on-line monitoring, pulsed electric field assistance), the metal leaching efficiency of sulfide ores is significantly improved (copper leaching rate ≥ 92%, gold dissociation rate ≥ 85%), the leaching cycle is shortened to 5 - 15 days, and the adaptability of the microbial community to extreme environments of high temperature (35 - 65°C) and high toxicity (Cu 2+ ≤ 15 g / L, As 3+ ≤ 5 g / L) is expanded. At the same time, through synergistic solutions (containing nanohematite, photosensitive ATP activators, etc.) and EPS function regulation (chelating density ≥ 8 mmol / g), the problems of mineral passivation and maintenance of microbial activity are solved, providing an efficient and low-consumption solution for the resource utilization of complex ores. Summary of the Invention

[0011] The present application provides an invention of a composite ore-leaching microbial community and its application in biohydrometallurgy to solve the above problems.

[0012] A composite ore-leaching microbial community is composed of the following strains according to the cell number ratio:

[0013] Acidithiobacillus ferrooxidans 30 - 45%

[0014] Acidithiobacillus thiooxidans 20 - 35%

[0015] Sulfobacillus thermosulfidooxidans 15 - 25%

[0016] Leptospirillum ferriphilum 10 - 20%

[0017] The above microbial community realizes the efficient leaching of metals in sulfide ores through synergistic metabolism, and the applicable temperature range is 35 - 65°C, and the pH is 1.2 - 2.5.

[0018] On the other hand, further, the above microbial community is obtained through directional domestication and cultivation, and the domestication conditions include:

[0019] Gradually increasing the concentration of toxic metal ions in the ore (Cu 2+ ≤15 g / L, As 3+ ≤5 g / L)

[0020] Alternately switching the redox potential (+400 mV to +650 mV)

[0021] Periodically applying mechanical stress (ultrasonic frequency 20 kHz, power 50 W, intermittent action).

[0022] The extracellular polymeric substances (EPS) secreted by the microbial community include:

[0023] Polysaccharide component (40 - 55 wt%)

[0024] Protein component (30 - 45 wt%)

[0025] Nucleic acid fragment (5 - 10 wt%)

[0026] The functional group density of chelating metal ions in the above EPS ≥ 8 mmol / g.

[0027] The application of the composite ore - leaching microbial community described in any one of the above in bio - metallurgy includes the following steps:

[0028] (1) Microbial community expansion culture: In a 9K medium containing Fe 2+ (5 - 10 g / L), S 0 (2 - 5 g / L), introducing CO 2 (1 - 3 vvm), and culturing with shaking at 45°C until the cell concentration ≥ 10 8 cells / mL;

[0029] (2) Ore pretreatment: The ore is crushed to a particle size of ≤5 mm, mixed with the bacterial solution at a solid-liquid ratio of 1:3, and a surfactant polyethylene glycol (0.1 - 0.5 wt%) is added;

[0030] (3) Leaching reaction: In an air-lift reactor, control the dissolved oxygen ≥4 mg / L, maintain the oxidation-reduction potential above +580 mV, and the leaching cycle is 5 - 15 days;

[0031] (4) Metal recovery: The target metal is recovered from the leaching solution by displacement precipitation or solvent extraction.

[0032] Among them, in step (3) we mentioned adopting a segmented temperature control strategy:

[0033] Maintain at 45 - 50 °C for the first 3 days to promote the attachment of the bacterial community, raise the temperature to 55 - 60 °C in the middle 5 days to accelerate the oxidation of sulfides, and lower the temperature to 40 °C in the later stage to prolong the activity of the bacterial community.

[0034] The metal leaching rates of the following ores by the bacterial community:

[0035] For chalcopyrite (CuFeS 2 ), the copper leaching rate ≥92%;

[0036] For arsenopyrite (FeAsS), the gold dissociation rate ≥85%;

[0037] For printed circuit boards, the copper recovery rate ≥95%.

[0038] The Acidithiobacillus ferrooxidans carries an exogenous arsenic resistance operon (ars operon), and its arsenic efflux efficiency is 5 times higher than that of the wild type;

[0039] The Acidithiobacillus thiooxidans overexpresses sulfur oxidase (soxCDYZ), and the thiosulfate oxidation rate increases by 300%;

[0040] The Sulfurimonas oxidans knocks out the quorum sensing inhibitory gene (qslA), and the biofilm formation ability is enhanced by 2.3 times;

[0041] The Leptospirillum ferrooxidans imports the heat shock protein gene (groEL), and the survival rate at 65 °C increases by 80%.

[0042] Decoupling of iron oxidation and sulfur oxidation pathways: By adding an electron shuttle (sodium anthraquinone-2-sulfonate), the oxidation of Fe 2+ and S 0 are carried out at different times;

[0043] Control of population metabolic balance: When the Cu 2+ concentration > 8 g / L, the self-inducing promoter triggers the population suicide gene (hok / sok) to maintain the viable cell density at 10 7 -10 8cells / mL;

[0044] Energy redistribution mechanism: Using a photobioreactor to supplement 630 nm red light to activate bacterial phytochrome and increase the ATP production efficiency by 40%.

[0045] Real-time monitoring of the sulfur species change on the mineral surface by online Raman spectroscopy and automatically adjusting the ventilation rate (0.5 - 5 vvm);

[0046] Applying a pulsed electric field (0.5 V, 100 Hz) to promote the transmembrane transport of the bacterial community;

[0047] When pH > 2.5, microcapsules slowly release acidic precursor substances (thiosulfate / ferrous sulfate).

[0048] Containing the following components (by mass concentration):

[0049] Electron transfer activator:

[0050] 2,3 - dimethoxy - 5 - methyl - 1,4 - benzoquinone (coenzyme Q0 analogue) 0.05 - 0.2 mM

[0051] Nano - hematite (α - Fe 2 O 3 , with a particle size of 20 - 50 nm) 1 - 3 g / L

[0052] Stress resistance enhancer:

[0053] Selenomethionine (SeMet) 50 - 200 μM

[0054] Thermophilic bacterium extract (Thermus thermophilus HB27) 0.5 - 2% v / v

[0055] Interface reaction promoter:

[0056] Zwitterionic surfactant (sulfobetaine SB3 - 12) 0.01 - 0.1%

[0057] Polydopamine - coated silica microspheres (PDA@SiO 2 , with a diameter of 200 nm) 0.5 - 2 g / L

[0058] Metabolic balance buffer:

[0059] Phosphoenolpyruvate (PEP) - malate shuttle system 5 - 10 mM

[0060] pH - adaptive tri - acid buffer system (phthalic acid / citric acid / boric acid)

[0061] Beneficial effects

[0062] In the context of the bottlenecks faced by traditional bioleaching technologies, such as poor adaptability of strains, long leaching cycles, and a sharp decline in activity under high-temperature environments, the present invention creatively constructs a multi-dimensional collaborative bioleaching system. This system takes a composite microbial community in a specific proportion as the core (Acidithiobacillus ferrooxidans 30-45%, Acidithiobacillus thiooxidans 20-35%, Sulfurimonas thiooxydans 15-25%, Leptospirillum ferriphilum with high temperature tolerance 10-20%). Through a combined domestication strategy of gradient toxicity domestication (Cu 2+ ≤15 g / L, As 3+ ≤5 g / L), dynamic potential switching (+400 mV to +650 mV), and periodic ultrasonic stimulation (20 kHz, 50 W), the microbial community forms extracellular polymers (EPS) rich in sulfhydryl / carboxyl groups (chelating density ≥8 mmol / g) in an extremely acidic environment (pH 1.2-2.5), effectively neutralizing the toxicity of heavy metals. On this basis, combined with genetic engineering modification techniques - the arsenic efflux efficiency of Acidithiobacillus ferrooxidans is increased by 5 times, the sulfur oxidation rate of Acidithiobacillus thiooxidans is increased by 300%, the biofilm of Sulfurimonas thiooxydans is thickened by 2.3 times, and the high-temperature survival rate of Leptospirillum ferriphilum is increased to 80%, an engineered microbial community with both strong stress resistance and high metabolic capacity is constructed.

[0063] In practical applications, this microbial community, through the synergistic effect of a segmented temperature control strategy (45-50 °C in the first 3 days to promote attachment, 55-60 °C in the middle 5 days to strengthen oxidation, and 40 °C in the later stage to maintain activity) and a photobioreactor (630 nm red light increases the ATP efficiency by 40%), combined with the decoupling of the anthraquinone-2-sulfonate-mediated iron / sulfur oxidation pathway, realizes the efficient leaching of complex ores such as chalcopyrite (copper leaching rate ≥92%) and arsenopyrite (gold dissociation rate ≥85%). The intelligent control system monitors the change of sulfur morphology in real time through on-line Raman spectroscopy, and the pulsed electric field (0.5 V, 100 Hz) is coupled to promote transmembrane transport. When pH > 2.5, microcapsules are triggered to slowly release thiosulfate / ferrous sulfate, forming a dynamic closed-loop control. The innovative formula of the synergistic solution (containing nanohematite electron acceptor, sulfobetaine surfactant, and photosensitive ATP activator) combined with EPS functional regulation not only prevents the formation of a passivation layer on the mineral surface but also shortens the leaching cycle to 5-15 days, with the efficiency increased by 2-3 times compared with the traditional process. The entire system shows excellent stability in high-temperature (35-65 °C) and high-metal-concentration environments through a metabolic balance buffer system (PEP-malate shuttle) and triacid self-adaptive pH regulation, providing a solution with both high efficiency and environmental adaptability for the resource utilization of complex sulfide ores. Detailed implementation manners

[0064] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description in combination with examples and comparative examples:

[0065] Example 1

[0066] A certain copper smelter processes arsenical chalcopyrite (CuFeS 2 with a grade of 10.2% and an As content of 1.8%), and uses the composite ore-leaching bacterial community of the present invention for bioleaching. First, the ore is processed by a jaw crusher and a ball mill to a particle size ≤ 5 mm (D90 = 4.3 mm), and the initial copper content is measured to be 8.75 g / kg and the arsenic content is 1.2 g / kg. It is mixed with the bacterial solution at a solid-liquid ratio of 1:3 (bacterial concentration 1.2×10 8 cells / mL), and 0.3% polyethylene glycol is added to improve the wettability of the mineral surface. During the bacterial community expansion stage, a 9K medium containing Fe 2+ 8 g / L and sulfur powder 3 g / L is used, and CO 2 (2 vvm) is introduced to maintain the pH at 1.8, and it is shaken and cultured at 45 °C for 48 hours to obtain a highly active bacterial solution.

[0067] The leaching process is carried out in a 20 m 3 air-lift reactor. In the initial stage, the temperature is controlled at 48 °C and the dissolved oxygen is 5 mg / L for 3 days. The bacterial community quickly attaches to the mineral surface, and the biofilm coverage rate reaches 78% as observed by scanning electron microscopy (only 32% for the untreated ore in the control group). In the middle stage, the temperature is raised to 58 °C, and 630 nm red light irradiation is simultaneously turned on (8 hours per day, intensity 50 μmol / (m 2 ·s)). At this time, 0.1 mM anthraquinone-2-sulfonic acid sodium is added to increase the Fe 2+ oxidation rate to 1.8 g / (L·h), and the sulfur oxidation is started 12 hours later to avoid electron competition. On the 5th day, elemental sulfur (S 0 ) on the mineral surface is detected by in-situ Raman spectroscopy to account for 42%, triggering the automatic increase of the ventilation volume to 3 vvm, and a pulsed electric field (0.5 V, 100 Hz) is applied for 2 hours every day to promote the transmembrane transport efficiency of the bacterial cells to increase by 2.1 times.

[0068] By the 8th day, the Cu 2+ concentration in the leaching solution rises to 9.2 g / L, the self-inducible promoter triggers the hok / sok system, and the viable cell density stabilizes at 3.2×10 7 cells / mL. In the later stage, the temperature is lowered to 40 °C, and a synergistic solution containing nanohematite (2 g / L) and sulfobetaine SB3-12 (0.05%) is supplemented, and the leaching is finally completed on the 12th day. Metal recovery is carried out by the iron powder displacement method. After displacement, the copper purity reaches 99.3%, and the arsenic solidification rate of the leaching residue is ≥ 95% as shown by toxicity detection. The key data comparison is as follows in the table:

[0069]

[0070] During the process, the genetically engineered bacterial strains showed significant advantages: Acidithiobacillus ferrooxidans carrying the ars operon made the As in the leaching solution3+ The concentration is always lower than 2 g / L, while the wild-type bacterial community experiences large-scale death when the As 3+ > 1 g / L; the thiosulfate oxidation rate of Acidithiobacillus overexpressing soxCDYZ is increased to 14 mM / h, effectively avoiding the passivation of the sulfur layer. The intelligent control system dynamically adjusts the parameters through real-time Raman spectroscopy data. When the pH is detected to rise to 2.6, the microcapsules release 1.2 g / L of thiosulfate, stabilizing the system pH at 2.1 ± 0.2. Finally, XRD analysis of the leaching residue shows that the main components are unreacted SiO 2 (62%) and jarosite minerals (34%) that solidify arsenic, meeting the environmental protection discharge standards. This case verifies the high efficiency and stability of the present invention in the treatment of complex arsenic-containing copper ores, saving about 40% in cost compared to traditional processes, and providing an innovative solution for the resource utilization of highly toxic sulfide ores.

[0071] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concepts. Therefore, the appended claims are intended to be interpreted to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present application.

[0072] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these changes and modifications.

Claims

1. A composite leaching bacterial community, characterized in that: It is composed of the following bacterial species in proportion to the number of cells: Acidithiobacillus ferrooxidans 30-45%; Acidithiobacillus thiooxidans 20-35%; Sulfobacillus thermosulfidooxidans 15-25%; Thermotolerant Leptospirillum ferriphilum 10-20%; The bacterial community achieves efficient leaching of metals in sulfide ores through synergistic metabolism, and is adapted to a temperature range of 35-65° C. and a pH of 1.2-2.

5.

2. The composite leaching bacterial community according to claim 1, characterized in that: The bacterial colony is obtained by directed domestication culture, and the domestication conditions include: Gradient increase in ore toxic ion concentration (Cu 2+ ≤15g / L, As 3+ ≤5g / L); Alternately switch the redox potential (+400mV to +650mV); Mechanical stress was applied periodically (ultrasonic frequency 20 kHz, power 50 W, intermittent action).

3. The composite leaching bacterial community according to claim 1, characterized in that: Extracellular polymers (EPS) secreted by bacteria include: Polysaccharide component (40-55 wt %); Protein component (30-45 wt%); Nucleic acid fragments (5-10wt%); The functional group density of chelated metal ions in the EPS is ≥8mmol / g.

4. An application of the composite leaching bacterial community as claimed in any one of claims 1 to 3 in biometallurgy, characterized in that The following steps are involved: (1) Bacterial expansion: in the presence of Fe 2+ (5-10g / L), S 0 (2-5g / L) 9K medium, introduce CO2 (1-3vvm), shake culture at 45℃ until the bacterial concentration is ≥10 8 cells / mL; (2) Ore pretreatment: crush the ore to a particle size of ≤5 mm, mix it with the bacterial solution at a solid-liquid ratio of 1:3, and add the surfactant polyethylene glycol (0.1-0.5 wt%); (3) Leaching reaction: In the airlift reactor, the dissolved oxygen is controlled to be ≥4 mg / L, the redox potential is maintained above +580 mV, and the leaching period is 5-15 days; (4) Metal recovery: The target metal is recovered from the leachate by displacement precipitation or solvent extraction.

5. The use according to claim 4, characterized in that: In step (3), a segmented temperature control strategy is adopted: Maintain 45-50℃ for the first 3 days to promote bacterial attachment; In the middle 5 days, the temperature rises to 55-60℃ to accelerate sulfide oxidation; In the later stage, the temperature is lowered to 40℃ to prolong the activity of the bacterial flora.

6. The use according to claim 4, characterized in that: The metal leaching rate of the bacterial community on the following ores: The copper leaching rate in chalcopyrite (CuFeS2) is ≥92%; The gold dissociation rate in arsenopyrite (FeAsS) is ≥85%; The copper recovery rate in printed circuit boards is ≥95%.

7. The composite leaching bacterial community according to claim 1, characterized in that Contains at least one genetically engineered strain: The Thiobacillus ferrooxidans carries an exogenous arsenic resistance operon (ars operon), and its arsenic efflux efficiency is 5 times higher than that of the wild type; The Acidithiobacillus overexpresses sulfur oxidase (soxCDYZ), and the thiosulfate oxidation rate is increased by 300%; The quorum sensing inhibitor gene (qslA) of the sulfur-oxidizing bacterium was knocked out, and the biofilm formation ability was enhanced by 2.3 times; The heat shock protein gene (groEL) is introduced into the Leptospira, and the survival rate at 65°C is increased by 80%.

8. The composite leaching bacterial community according to claim 1, wherein the metabolic characteristics thereof include: Decoupling of iron oxidation from sulfur oxidation pathways: Fe 2+ Oxidation and S 0 Oxidation is carried out in time; Group metabolic balance control: When Cu 2+ When the concentration is >8g / L, the self-inducing promoter triggers the group suicide gene (hok / sok) to maintain the viable bacterial density at 10 7 -10 8 cells / mL; Energy redistribution mechanism: Use photobioreactor to supplement 630nm red light to activate bacterial photosensitive pigments and increase ATP production efficiency by 40%.

9. An intelligent leaching device based on the bacterial community of claim 1, characterized in that: The changes in sulfur forms on the mineral surface are monitored in real time through online Raman spectroscopy, and the ventilation volume (0.5-5vvm) is automatically adjusted; Applying a pulsed electric field (0.5 V, 100 Hz) promoted bacterial transport across the membrane; When pH>2.5, the microcapsules slowly release the acidic precursor (thiosulfate / ferrous sulfate).

10. A biometallurgical synergistic solution for the composite leaching bacterial community according to claim 1, characterized in that Contains the following components (by mass concentration): Electron Transport Activators: 2,3-Dimethoxy-5-methyl-1,4-benzoquinone (Coenzyme Q0 analogue) 0.05-0.2mM; Nano hematite (α-Fe2O3, particle size 20-50nm) 1-3g / L; Stress enhancer: Selenomethionine (SeMet) 50-200 μM; Extreme thermophilic bacteria extract (Thermus thermophilus HB27) 0.5-2% v / v; Interfacial reaction accelerator: Zwitterionic surfactant (sulfobetaine SB3-12) 0.01-0.1%; Polydopamine coated silica microspheres (PDA@SiO2, diameter 200nm) 0.5-2g / L; Metabolic Equilibration Buffer: Phosphoenolpyruvate (PEP)-malate shuttle system 5-10 mM; pH adaptive tri-acid buffer system (phthalic acid / citric acid / boric acid).

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