A method for improving carbon fixation and leaching efficiency of sulfide ore leaching microorganisms

Abstract

The application discloses a method for improving carbon fixation and leaching efficiency of sulfide ore leaching microorganisms, and belongs to the technical field of bio-metallurgy, and mainly comprises the following steps: inoculating three strains of acidophilic bacteria S. thermosulfidooxidans, A. ferrooxidans and L. ferrooxidan with high sulfide ore leaching efficiency in a 9K basic culture medium for culture, adding high-concentration non-ferrous metal smelting flue gas for culture and domestication, and then improving the carbon fixation efficiency and leaching efficiency of the sulfide ore leaching microorganisms through microbial community compounding and response surface analysis. The method can make the carbon fixation rate of the sulfide ore leaching microorganisms reach 10.52 mg / L / d, and the leaching rate of copper in the copper sulfide is 85.03% higher than that of the flue gas-free group, and the time is shortened by 3-5 days. In addition, after leaching for 14 days, the concentration of the leaching microorganisms reaches 3.45x10 9 cells / mL. The application has the advantages of rapidness, convenience, high-efficiency carbon fixation and high leaching rate, and has a good application prospect in the technical field of bio-metallurgy.

Description

Technical Field

[0001] This invention belongs to the field of biometallurgical technology, specifically relating to a method for improving the carbon fixation and leaching efficiency of microorganisms in sulfide ore leaching. Background Technology

[0002] Currently, the main methods for treating non-ferrous metal smelting flue gas include physical, chemical, and biological methods. Among these, biological carbon fixation, utilizing microalgae for photosynthesis to fix CO2, has advantages such as environmental friendliness, high carbon fixation performance, and high biomass added value. However, acidic gases such as CO2, SO2, and NOx in smelting flue gas can easily acidify the algal solution, hindering the carbon fixation function of microalgae. Leaching microorganisms, on the other hand, are autotrophic microorganisms capable of utilizing various energy sources, exhibiting acidophilic and heavy metal resistance characteristics. Therefore, elements such as C, N, and S in smelting flue gas can be utilized by leaching microorganisms to fix CO2 while effectively absorbing acidic gases. Thus, utilizing the characteristics of leaching microorganisms can not only improve the leaching rate of sulfide ores but also achieve waste gas resource utilization, thereby achieving flue gas purification. However, in actual cultivation, leaching microorganisms are small in size, resulting in relatively low overall carbon fixation performance, and the leaching cycle of sulfide ores is relatively long. Therefore, exploring a method to improve the carbon fixation efficiency of microorganisms in sulfide leaching is of great significance for achieving "carbon peak" and "carbon neutrality". Summary of the Invention

[0003] The purpose of this invention is to provide a method for improving the carbon fixation and leaching efficiency of microorganisms in sulfide ore leaching. This invention not only provides a highly efficient leaching method for sulfide ore, but also effectively avoids the environmental pollution caused by metal smelting fumes.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for improving the efficiency of microbial carbon fixation and leaching of sulfide ores involves introducing flue gas into a microbial leaching system; further, the flue gas includes non-ferrous metal smelting flue gas containing CO2, SO2, and NO. X gas.

[0006] NO X The gas refers to nitrogen oxides, including a mixture of NO and NO2.

[0007] The flue gas contains 4%–6% CO2, 150–300 ppm SO2, and NO2. X The concentration is 100–200 ppm, and the gas flow rate is 0.25–0.35 vvm.

[0008] The leaching microorganisms include: Sulfobacillus thermosulfidooxidans, Acidithiobacillus ferrooxidans, and Leptospirillum ferrooxidan.

[0009] The total cell inoculation concentration of the mineral-leaching microorganisms was 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 cells / mL. Preferably, the concentration ratio of each strain is 1:1:1.

[0010] The system temperature is 30℃~50℃, the rpm is 160rpm~190rpm, and the pH value is 1~2.5.

[0011] The leaching microorganisms, after being domesticated, are used for leaching, specifically including:

[0012] (1) The leaching microorganisms were inoculated into a culture medium containing sulfide minerals and subjected to at least three cycles of acclimatization culture under the condition of adding flue gas, with each cycle lasting 18 to 26 days.

[0013] (2) The leaching microorganisms obtained in step (1) are inoculated into a culture medium containing sulfide minerals after strain compounding, and leached for 18 to 24 days under the condition of adding flue gas.

[0014] Step (1) The acclimatization and cultivation method is as follows: During the acclimatization process, for the first two cycles, CO2 containing 4%–6% v / v, SO2 containing 150–300 ppm, and NO2 containing 100–200 ppm are added. X The flue gas is then acclimated by adding 3% to 10% v / v CO2 gas during the next cycle.

[0015] The leaching method for step (2) is as follows: The leaching solution contains 4%–6% v / v CO2, 150–300 ppm SO2, and 100–200 ppm NO. X Leaching from the flue gas;

[0016] Furthermore, during the domestication and cultivation of leaching microorganisms or during leaching, the culture medium used is basal 9K medium with a gas flow rate of 0.25–0.35 vvm; the sulfide ore slurry concentration is 4–6%; the culture temperature is 30℃–50℃; the pH value is 1–2.5; and the rotation speed is 160 rpm–190 rpm.

[0017] Furthermore, the bacterial inoculation concentration in steps (1) and (2) is 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 cells / mL.

[0018] The leaching rate of sulfide ore by the method of the present invention is 76.89-83.44%, and the average carbon fixation rate is 9.68-10.26 mg / L / d.

[0019] Currently, there are few methods for improving the carbon fixation efficiency of microorganisms in sulfide leaching. This invention has the following beneficial effects:

[0020] (1) Through the domestication and condition optimization of the present invention, the system can improve the carbon fixation efficiency of leaching microorganisms and further improve the extraction rate of metal ions in sulfide ores.

[0021] (2) This invention helps to remove acidic gases, such as SO2 and NOx, from flue gas in non-ferrous metal smelting.

[0022] (3) Through domestication and condition optimization, this invention found that the carbon fixation rate reached 10.52 mg / L / d, and the concentration of leaching microorganisms reached 3.45 × 10⁻⁶ after leaching for 14 days. 9 The copper leaching rate reached 85.03% within a shortened time of 3–5 days. Compared with other methods, this method has the advantages of being fast, convenient, highly efficient in carbon fixation, and having a high leaching rate. Attached Figure Description

[0023] Figure 1 To add 3% flue gas (3% CO2 + 250ppm SO2 + 150ppm NO) X Growth curves of microorganisms leaching sulfide minerals under certain conditions.

[0024] Figure 2 To add 3% flue gas (3% CO2 + 250ppm SO2 + 150ppm NO) X Leaching rate of sulfide ore under the following conditions.

[0025] Figure 3 The growth curves of leaching microorganisms in sulfide minerals under different concentrations of flue gas were obtained.

[0026] Figure 4 The carbon fixation rate of sulfide ore leaching microorganisms under different concentrations of flue gas was determined.

[0027] Figure 5 Growth curves of microorganisms in sulfide ore leaching under different gas rate conditions with 5% flue gas added.

[0028] Figure 6 The carbon fixation rate of sulfide mineral leaching microorganisms under different gas rate conditions was determined by adding 5% flue gas.

[0029] Figure 7The growth curves of leaching microorganisms from sulfide minerals under different initial pH conditions at an optimal gas flow rate of 0.3 vvm are shown.

[0030] Figure 8 The carbon fixation rate of microorganisms in sulfide mineral leaching under different initial pH conditions at an optimal gas flow rate of 0.3 vvm is given.

[0031] Figure 9 Response surface interaction analysis for flue gas concentration and gas flow rate.

[0032] Figure 10 Response surface interaction analysis was performed on flue gas concentration and initial pH value.

[0033] Figure 11 Response surface interaction analysis was performed on gas flow rate and initial pH value.

[0034] Figure 12 The growth curves of microorganisms leaching sulfide minerals are shown under flue gas and non-flue gas conditions.

[0035] Figure 13 The leaching rate of sulfide ore under flue gas conditions.

[0036] Figure 14 The growth curves of leaching microorganisms from sulfide minerals before and after domestication under optimal flue gas conditions.

[0037] Figure 15 The leaching rate of sulfide ore before and after domestication under the optimal conditions of adding flue gas.

[0038] Figure 16 The carbon fixation rate of sulfide ore leaching microorganisms before and after domestication under optimal flue gas conditions was determined.

[0039] Figure 17 The growth curves of microorganisms leaching sulfide minerals under conditions of adding 5% pure CO2 and 5% flue gas are shown.

[0040] Figure 18 The carbon fixation rate of sulfide ore leaching microorganisms under conditions of 5% pure CO2 and 5% flue gas addition.

[0041] Figure 19 The leaching rate of sulfide ore under conditions of adding 5% pure CO2 and 5% flue gas. Detailed Implementation

[0042] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below. The technical solutions of the present invention will now be described in detail with reference to the accompanying drawings. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0043] This invention provides, for example Figure 1-11The method shown here for improving the carbon fixation efficiency of microorganisms in sulfide leaching specifically includes the following steps:

[0044] (1) Three autotrophic bacteria, S. thermosulfidooxidans, A. ferrooxidans and L. ferrooxidans, which showed high leaching efficiency of sulfide minerals under medium and high temperature conditions, were selected and cultured in 9K basal medium (inoculation concentration of each bacterium: 1.5 × 10⁻⁶). 7 cells / mL ~2.5×10 7 The cultivation conditions were as follows: sulfide ore slurry concentration of 5%, cultivation temperature of 45℃, initial pH of 1.5, stirring speed of 180 rpm, and aeration rate of 0.3 vvm (intermittent aeration). For the first two cycles, flue gas containing 5% v / v CO2, 250 ppm SO2, and 150 ppm NOx was introduced. For the subsequent cycle, 10% v / v CO2 was added. Three cycles of acclimatization cultivation were carried out, each lasting 25 days, until the leaching microorganisms could grow rapidly and stably for three cycles, after which the acclimatization was stopped.

[0045] (2) The leaching microorganisms obtained in step (1) were mixed with strains in a ratio of 1:1:1, and the total inoculum concentration was 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 cells / mL, selected at 5% v / v CO2, 250 ppm SO2 and 150 ppm NO. X Leach for 25 days under gaseous conditions, with other leaching conditions the same as in step (1).

[0046] During the cultivation process, 10 mL samples were taken at the same time every day, and the cell concentration and copper ion concentration in the culture medium were determined by methods such as optical microscopy counting and inductively coupled atomic emission spectrometry. The concentrations of relevant gases at the inlet and outlet were measured by a flue gas analyzer, and the fixed percentages of CO2, SO2 and NOx were calculated.

[0047] (3) Single-factor optimization of the leaching microbial system with high carbon fixation effect and high sulfide leaching rate in step (2) was performed to obtain the best carbon fixation effect. During the logarithmic growth phase of its culture, it was inoculated into the control group (CK), 3% (3% CO2, 250 ppm SO2 and 150 ppm NO2) X ), 5% (5% CO2, 250ppm SO2 and 150ppm NO) X ), 7% (7% CO2, 250ppm SO2 and 150ppm NO) X ) and 10% (10% CO2, 250ppm SO2 and 150ppm NO)X Five flue gas concentrations in sulfide mineral culture medium.

[0048] During the culture process, 10 mL samples were taken at the same time every day, and the cell concentration, copper ion concentration and total carbon (TC) in the culture medium were determined by optical microscopy counting method, inductively coupled atomic emission spectrometry, and total organic carbon analyzer, and the average daily carbon fixation rate was calculated.

[0049] (4) Take the leaching microorganisms with the optimal flue gas concentration obtained from the logarithmic phase in step (3) and inoculate them into a new sulfide leaching microorganism culture medium. Then, culture them at four gas flow rates of 0.1 vvm, 0.2 vvm, 0.3 vvm and 0.4 vvm respectively. Other steps are the same as in step (3).

[0050] (5) Take the leaching microorganisms with the optimal gas flow rate obtained from the logarithmic phase culture in step (4) and inoculate them into culture media with initial pH values ​​of 1, 1.5, 2 and 2.5. Other steps are the same as in step (3).

[0051] (6) The single-factor experiments in steps (3), (4), and (5) were analyzed using Design-Expert 8 software to obtain the optimal conditions for carbon fixation and sulfide leaching culture: CO2 concentration in flue gas was 5%, gas flow rate was 0.3 vvm, and pH was 1.5.

[0052] As shown in Table 1, after multiple acclimatizations, strain combinations, and condition optimizations, the carbon fixation efficiency and sulfide leaching efficiency of the leaching microorganisms were significantly improved. Under optimal culture conditions, the carbon fixation rate reached 10.52 mg / L / d, and the copper leaching rate reached 85.03% within a 3–5 day timeframe. Furthermore, after 14 days of leaching, the concentration of the leaching microorganisms reached 3.45 × 10⁻⁶. 9 cells / mL.

[0053] Table 1. Microbial carbon fixation and bioleaching rate of sulfide minerals under optimal conditions (experimental groups 1, 2, and 3 are parallel experiments).

[0054]

[0055]

[0056] Implementation Case 1

[0057] Figure 12-13 The image shows the above mixed bacteria inoculated into the control group (CK) without flue gas and with flue gas containing 5% concentration (Gas: 5% CO2, 250ppm SO2, and 150ppm NO2). XUnder optimal culture conditions (gas flow rate of 0.3 vvm, pH of 1.5), the sample was cultured in a 5% slurry concentration with an initial inoculum concentration of 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 The inoculum concentration was kept constant, and other culture conditions were as described above (temperature 45℃, rotation speed 180 rpm). Results showed that after the addition of flue gas, the leaching microorganisms in sulfide minerals reached a maximum of 2.97 × 10⁻⁶ cells / mL during bioleaching. 9 The concentration of copper ions reached 11.71 mg / L in the cell / mL group. In contrast, the smokeless group reached its maximum concentration of 1.39 × 10⁻⁶ cells / mL around day 22 of bioleaching. 9 The concentration of copper ions was 7.29 mg / L. Compared with the group without flue gas, the biomass of leaching microorganisms increased significantly by 113.67% after the addition of flue gas, the leaching rate of sulfide ore increased by approximately 60.63%, and the leaching cycle was shortened by about 5 days. This experiment demonstrates that the introduction of flue gas significantly improves the biomass and leaching rate of sulfide ore, and the increase in biomass indicates an increase in the carbon fixation capacity of leaching microorganisms.

[0058] Implementation Case 2

[0059] Figure 14-16 The image shows the above mixed bacteria inoculated with flue gas containing 5% CO2, 250 ppm SO2, and 150 ppm NO2 before and after acclimatization. X Under optimal culture conditions (gas flow rate of 0.3 vvm, pH of 1.5), the sample was cultured in a 5% slurry concentration with an initial inoculum concentration of 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 The inoculum concentration was kept constant, and other culture conditions were as described above. Results showed that after flue gas acclimatization, the leaching microorganisms for sulfide minerals reached their maximum value of 3.51 × 10⁻⁶ cells / mL during bioleaching on day 16. 9 The bioleaching microorganisms at a concentration of [number of cells / mL] achieved a carbon fixation rate of 10.47 mg / L / d, a copper ion concentration of 12.03 mg / L, and a leaching rate of 90.23%. In contrast, the leaching microorganisms for untamed sulfide minerals reached their maximum value of 2.07 × 10⁻⁶ cells / mL around day 20 of bioleaching. 9The leaching rate was 57.31%, with a carbon fixation rate of 3.76 mg / L / d and a copper ion concentration of 7.64 mg / L. Compared to the unacclimated group, the addition of flue gas increased the biomass of leaching microorganisms by 69.57%, the carbon fixation rate by approximately 178.46%, and the leaching rate of sulfide ore by approximately 57.46%, while shortening the leaching cycle by about 4 days. This experiment demonstrates that acclimation effectively improves the carbon fixation rate of sulfide ore microorganisms and enhances the leaching efficiency of sulfide ore.

[0060] Implementation Case 3

[0061] Figure 17-19 The above-mentioned mixed bacteria were observed in 5% pure CO2 and 5% flue gas (5% Gas: 5% CO2, 250 ppm SO2 and 150 ppm NO). X Under optimal culture conditions (gas flow rate of 0.3 vvm, pH of 1.5), the sample was cultured in a 5% slurry concentration with an initial inoculum concentration of 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 The cell / mL concentration was kept consistent, and other culture conditions were as described above. Results showed that after adding 5% flue gas, the bacterial concentration reached its maximum of 3.22 × 10⁻⁶ cells / mL on day 16 of bioleaching. 9 The carbon fixation rate was 9.87 mg / L / d, and the copper ion concentration was 10.31 mg / L. The leaching system with added 5% pure CO2 reached its maximum value of 2.56 × 10⁻⁶ cells / mL around day 18. 9 The biomass of the leaching microorganisms was 7.56 mg / L / d, and the carbon fixation rate was 7.56 mg / L / d. The copper ion concentration was 8.99 mg / L. Compared with the addition of pure CO2 gas, the addition of flue gas increased the biomass of the leaching microorganisms by 25.41%, the carbon fixation rate by approximately 30.56%, the leaching rate of sulfide ore by approximately 14.68%, and shortened the leaching cycle by about 2 days. This experiment demonstrates that, compared with the addition of pure CO2 gas, the addition of flue gas effectively improved the carbon fixation rate of the leaching microorganisms of sulfide ore.

Claims

1. A method for improving the efficiency of microbial carbon fixation and leaching in sulfide ores, characterized in that, Non-ferrous metal smelting flue gas containing CO2, SO2, and NO is introduced into a microbial leaching system. x The flue gas contains CO2 at a concentration of 4%–6% v / v, SO2 at a concentration of 150–300 ppm, and NO at a concentration of [missing information]. x The concentration was 100–200 ppm, and the gas flow rate was 0.25–0.35 vvm; the leaching microorganisms included Sulfobacillus thermosulfidooxidans, Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans The leaching microorganisms, after being domesticated, are used for leaching, specifically including: (1) The leaching microorganisms were inoculated into a culture medium containing sulfide ore and subjected to three cycles of acclimatization culture under the condition of adding flue gas, each cycle lasting 18 to 26 days; among them, the first two cycles were supplemented with CO2 containing 4% to 6% v / v, SO2 containing 150 to 300 ppm, and NO containing 100 to 200 ppm. x The flue gas is then acclimated by adding 3% to 10% v / v CO2 gas during the next cycle. (2) The leaching microorganisms obtained in step (1) are inoculated into a culture medium containing sulfide minerals after strain compounding. The medium contains 4%–6% v / v CO2, 150–300 ppm SO2, and 100–200 ppm NO. x The gas was leached into the flue gas for 18–24 days.

2. The method according to claim 1, characterized in that, Step (2): The total cell inoculation concentration of the leaching microorganisms is 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 cells / mL; the concentration ratio of each strain was 1:1:

1.

3. The method according to claim 1 or 2, characterized in that, The system temperature is 30℃~50℃, the rotation speed is 160rpm~190rpm, and the system pH value is 1~2.

5.

4. The method according to claim 1 or 2, characterized in that, When leaching ore microorganisms are domesticated and cultured or when leaching ore, the culture medium used is basal 9K medium, and the concentration of sulfide ore pulp is 4-6%.

5. The method according to claim 1 or 2, characterized in that, The bacterial inoculation concentration in step (1) is 1.5 × 10⁻⁶. 7 cells / mL ~2.5×10 7 cells / mL.

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