C 14 -HSL controlled acidophilic bacteria leaching of chalcopyrite

Abstract

The present invention discloses C 14 The invention discloses a method for regulating acidophilic bacteria leaching, which belongs to the field of biological leaching technology. The invention finds that different types of AHL signal molecules can have different effects on the growth and leaching of acidophilic bacteria at different concentrations and different addition times. The signal molecule control experiment confirms that C 14 At certain concentrations, the HSL signal molecule can promote and enhance the production of extracellular polysaccharides and fulvic acid by the strain, as well as its ability to adhere to minerals in the later stages of leaching, thereby increasing the strain's growth rate and mineral leaching efficiency. By regulating the concentration of the signal molecule, the rate of acidophilic leaching and its growth can be adjusted. This method is simple to operate, has low production costs, and is environmentally friendly. This method solves the problem of difficult control during mixed acidophilic leaching, promotes the industrial development of biometallurgical technology, and improves leaching production efficiency.

Description

Technical Field

[0001] The present invention relates to the field of bioleaching technology, and more particularly to C 14 -HSL method to improve the efficiency of acidophilic bacteria leaching chalcopyrite. Background Art

[0002] Quorum sensing is a mechanism by which microorganisms regulate their life activities based on population density. When the population density reaches a certain critical value, microorganisms will exhibit "social" behavior. Microorganisms use signal molecules (autoinducers AI) secreted in the environment as a basis for judging their population density. As the bacterial population density increases, AIs accumulate in the external environment. Signal molecules are transported through the cell membrane and bind to corresponding receptors, subsequently causing downstream gene expression, regulating physiological and biochemical processes such as root nodulation, bioluminescence, protein secretion, motility, virulence factor production, plasmid transfer and biofilm formation. The intercellular signaling system of Gram-negative bacteria depends on diffusible small molecules such as N-acyl homoserine lactone (AHL). Some AHL molecules promote the attachment of acidophilic bacteria and biofilm formation. The strategy of using signal molecules to improve the iron and sulfur oxidation ability of strains is expected to lay a theoretical foundation for improving the efficiency of strain leaching in the biometallurgical industry. Most iron-oxidizing and sulfur-oxidizing bacteria in leaching microorganisms are Gram-negative bacteria, and the main signal molecules are AHLs. C 14 -HSL is a promising AHL molecule.

[0003] Acidithiobacillus ferrooxdians (A.ferrooxdians) is a Gram-negative, chemoautotrophic, acidophilic aerobic bacterium. As a model strain in bioleaching, it is commonly found in iron-containing or sulfated mine water. It uses CO2 as the only carbon source and relies on oxidizing Fe 2+ or S, and reduces sulfur compounds to obtain energy. A.ferrooxdians is considered to be an important member of bioleaching bacteria for metal recovery and has application potential in leaching metals such as copper, zinc, nickel, uranium, arsenic and cobalt from low-grade ores. There are two density sensing systems in A.ferrooxidans. The first one (AHL-QS) is a typical LuxI / R type, and the second one is an atypical QS system. The main chain length of the acyl homoserine lactones (AHLs) produced is C 14, which has biological activity. The other is Acidithiobacillus thioooxidans (A. thioooxidans), which is an extremely acidophilic, chemical rock autotrophic, Gram-negative, rod-shaped microorganism. A. thioooxidans grows and survives by autotrophically utilizing elemental sulfur and reduced inorganic sulfur compounds (RISCs) as energy sources, but it cannot utilize Fe 2+ The energy or electrons obtained from oxidation are used to fix carbon dioxide and for other anabolic processes. It is one of the most critical sulfur-oxidizing microorganisms associated with bioleaching processes and can be successfully applied to extract metals from low-grade copper sulfide ores and contaminated tailings. A. thioooxidans grown in sulfur medium produces C 10 -HSL and C 12 -HSL.

[0004] Traditional mining, beneficiation, and metallurgical processes for processing these mineral resources suffer from low efficiency, lengthy processes, high production costs, severe environmental pollution, and low resource utilization. Biometallurgy is a new technology that uses microorganisms to selectively leach valuable elements from ores to directly produce high-purity metals and their materials. With its short processes, low costs, environmental friendliness, and low pollution levels, it has become a cutting-edge technology in global mineral processing. However, due to shortcomings such as the long microbial growth cycle and a lack of regulatory control, slow leaching rates and low leaching rates are obstacles to the industrial application of biometallurgy. Therefore, enhancing the role of microorganisms by increasing the strains' ability to oxidize iron and sulfur is a key factor in improving leaching efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention provides a promising method for regulating acidophilic bacteria leaching using AHL molecules, which can significantly improve leaching efficiency.

[0006] C 14 -HSL regulates the method for acidophilic bacteria leaching, the C 14 -HSL molecular formula is C 18 H 33 O3N, specifically C is added during the acidophilic bacteria leaching process 14 -HSL.

[0007] The mineral types in the leaching process include at least one of chalcopyrite and pyrite.

[0008] The acidophilic bacteria include at least one of the mesophilic bacteria Acidithiobacillus ferrooxdians and Acidithiobacillus thiooxidan.

[0009] Furthermore, C 14 -HSL was added in an amount of 0.4-0.6 μM.

[0010] It is preferred to add C before adding the leaching bacteria. 14 -HSL. Specifically, the 9K culture medium with the added mineral sample was stabilized for 72 hours and then C 14 -HSL was added to the stable 9K medium; then the two acidophilic bacteria were added in equal proportion to the medium with C 14 -HSL stable 9K medium.

[0011] Furthermore, the leaching system temperature is 28-30°C, pH is 1.5-2.0, and the bacterial inoculum size is 2×10 7 -2.5×10 7 cells / ml, pulp concentration: 1.5-2.5%, leaching time: 22-26 days, rotation speed: 150-180rpm.

[0012] The method of the present invention specifically comprises the following steps:

[0013] Step 1: Weigh 2 g of chalcopyrite passed through a 200-mesh sieve into a 250 ml conical flask, add 100 ml of 9k medium to form a leaching system with a slurry concentration of 2%, adjust the pH with 10% sulfuric acid, and stabilize the pH to 2.0 after 72 hours to obtain 9k medium;

[0014] Step 2: The acidophilic bacteria Af and At were cultured separately in a 9K medium containing divalent iron, the composition of which was 3 g / L (NH4)2SO4, 0.5 g / L MgSO4·7H2O, 0.5 g / L K2HPO4, 0.1 g / L KCl, and 0.01 g / L Ca(NO3)2; the initial pH value of the medium was adjusted to 2.0 with 10% H2SO4, and the amounts of substrates added were 44.7 g / L FeSO4·7H2O, 10 g / L sulfur powder, 2% chalcopyrite, and 2% pyrite, respectively; the culture was carried out in a shaker at 30°C and 180 rpm, and a bacterial culture sample was taken when the culture reached the mid-logarithmic phase;

[0015] Step 3: Add C to the 9k medium in step 1 14 -HSL molecules to a concentration of 0.5 μM, and then the two bacteria obtained in step 2 were added to the culture medium in equal proportions, with a bacterial concentration of 2×10 7 cells / ml for 24 days in a shaker at 30°C and 180 rpm.

[0016] When the present invention is used, the supernatant is taken for determination every 3 days; and the bacterial cells and slag are taken for determination after culturing for 24 days.

[0017] Specifically, it is the determination of physical and chemical parameters related to leaching: including the concentration of total copper and total iron in the leaching solution, the concentration of attached bacteria, the extraction and determination of extracellular polymeric substances (EPS), and the characterization of minerals.

[0018] The method for determining the concentration of attached bacteria of the present invention comprises the following steps: 2 ml of a sample is centrifuged in a low-speed centrifuge at 3000 r / min for 6 minutes to separate the bacterial liquid from the mineral in the solution, the upper layer of free bacterial liquid is removed, a sterile 9k solution is added to the lower layer of mineral to make up to 2 ml, the sample is vortexed for 20 minutes, and the sample is centrifuged at 3000 r / min for 6 minutes to separate the adsorbed microorganisms from the mineral, and the adsorbed microorganisms are counted using a hemocytometer.

[0019] Extraction and determination of extracellular polymers of the present invention: After 24 days of culture, the culture medium was centrifuged at 10,000 rpm and 4°C for 10 minutes. The supernatant was collected and filtered through a 0.22 μm pore size filter under sterile conditions to eliminate residual bacteria. The obtained supernatant contained EPS. Three-dimensional fluorescence characterization was performed using a Hitachi F-7000 fluorescence spectrophotometer (Hitachi Scientific Instruments Beijing Co., Ltd., Japan) to determine the composition of extracellular polymers. The sampling interval was 5 nm, the excitation wavelength range was 200-600 nm; the emission spectrum was scanned from 200 to 600 nm at a scanning speed of 3000 nm / min with an increment of 5 nm.

[0020] Polysaccharide determination was performed using glucose as the standard. 300 μL of sample was mixed with 900 μL of anthrone sulfate in an EP tube, and the mixture was placed in a constant temperature water bath at 98°C. After reacting for 20 min, OD625 nm was measured.

[0021] Characterization of the minerals: After the leaching experiment, all solutions were filtered with neutral filter paper. The slag was washed three times with acidified water (pH = 2.0) and dried in an oven at 40°C before subsequent testing. Changes in the mineral phase, surface functional groups, and morphological characteristics after leaching were analyzed using X-ray diffractometer, Fourier transform infrared spectrometer, and field emission scanning electron microscopy.

[0022] The results show:

[0023] (1) Compared with other AHL signaling molecules, the addition of C 14 -HSL, with a concentration of 0.5 μM and added on day 0, had the best leaching effect on chalcopyrite leaching in the Af and At co-culture system.

[0024] (2) Add C 14 -HSL promoted the attachment of bacteria in the Af and At co-culture system, promoted the production of EPS, and increased the concentrations of polysaccharides and fulvic acid in EPS. The continuous increase of EPS in the bioleaching system was beneficial to promoting mineral dissolution.

[0025] (3) XRD, FTIR and SEM analysis results show that the addition of C 14 -HSL causes the chalcopyrite diffraction peak to weaken, the peak associated with extracellular polymers to enhance, and the corrosion pits on the mineral surface to become more obvious.

[0026] In order to solve the problem of low bioleaching efficiency, the present invention provides a method for promoting the leaching efficiency of acidophilic bacteria by using quorum sensing signal molecules. 14 -HSL explored the experimental verification of the physicochemical parameters, mineral attachment, and EPS production of acidophilic bacteria. 0.5 μM C 14 -HSL addition is beneficial to the leaching of minerals. 14 -HSL promoted mineral leaching and strain growth. The concentrations of polysaccharides and fulvic acid in EPS were higher than those in other experimental groups, thereby improving the iron-sulfur oxidation ability of the strain. This was achieved through the novel signal molecule C 14 The strategy of using -HSL to enhance the iron-sulfur oxidation capacity of acidophilic bacteria lays a theoretical foundation for improving the leaching efficiency of strains in the biometallurgical industry, and also provides a new approach for solving environmental pollution problems such as acidic emissions, and has broad development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Changes in physicochemical parameters when different signal molecules were added to the Af and At co-culture system to leach chalcopyrite: (a) total copper; (b) total iron; (c) pH; (d) redox potential.

[0028] Figure 2 Changes in the physical and chemical parameters of chalcopyrite leached in the Af and At co-culture system with the addition of different concentrations of signal molecules: (a) total copper; (b) total iron; (c) pH; (d) redox potential.

[0029] Figure 3 Changes in the physicochemical parameters of chalcopyrite leached by adding signal molecules at different times in the co-culture system of Af and At: (a) total copper; (b) total iron; (c) pH; (d) redox potential.

[0030] Figure 4 The change of bacterial concentration when adding signal molecules to leaching chalcopyrite in the co-culture system of Af and At;

[0031] Figure 5 Three-dimensional fluorescence spectra of extracellular polymers when signal molecules were added to the co-culture system of Af and At to leach chalcopyrite: (a) methanol control group; (b) C 14 -HSL three-dimensional fluorescence map;

[0032] Figure 6The concentration of extracellular polysaccharide when the signal molecules are added to the co-culture system of Af and At to leach chalcopyrite;

[0033] Figure 7 C 14 -XRD patterns of mineral leaching residues (c-chalcopyrite, p-pyrite, q-quartz) under the influence of HSL;

[0034] Figure 8 C 14 -FTIR spectrum of mineral leaching residue under the influence of HSL;

[0035] Figure 9 SEM images of (a) untreated chalcopyrite, (b) non-biological acid leaching residue, (c) methanol control group bioleaching residue, (d) C 14 -HSL group bioleaching residue. DETAILED DESCRIPTION

[0036] The present invention is described in detail below through specific implementation cases. The specific implementation cases are only examples and are not intended to limit the scope of implementation of the present invention.

[0037] Selection and processing of mineral raw materials in the present invention: The mineral is chalcopyrite, which comes from Dongchuan, Yunnan, and is purchased from Mingfa Mineral Trading Company. The ore sample is crushed with a hammer to a particle size of about 1 mm, ground by a crusher, and dry-sieved to obtain an ore sample with a particle size of less than 74 μm.

[0038] The control groups in the embodiments of the present invention include: a sterile control group and a methanol-only added control group.

[0039] Example 1:

[0040] Step 1: Weigh 2 g of chalcopyrite sample passed through a 200-mesh sieve into a 250 ml conical flask, add 100 ml of 9k culture medium to form a leaching system with a slurry concentration of 2%, adjust the pH with 10% sulfuric acid, and after 72 hours, the pH stabilizes to 2.0 to obtain 9k culture medium. Repeat the above steps to obtain 8 bottles of 9k culture medium for later use.

[0041] Step 2: Acidophilic bacteria Af and At were cultured separately in 9K medium containing divalent iron (3 g / L (NH₄)₂SO₄), 0.5 g / L MgSO₄·7H₂O, 0.5 g / L K₂HPO₄, 0.1 g / L KCl, and 0.01 g / L Ca(NO₃)₂. The initial pH of the medium was adjusted to 2.0 with 10% H₂SO₄. Substrate additions included 44.7 g / L FeSO₄·7H₂O, 10 g / L sulfur powder, 2% chalcopyrite, and 2% pyrite. Cultures were shaken at 30°C in an incubator at 180 rpm. Samples of the culture medium were collected at mid-logarithmic phase (approximately 6 days) for later use.

[0042] Step 3: Add the same amount of C to the 8 bottles of 9k medium in step 1. 14 -HSL molecules to a concentration of 0.5 μM, and then add the two bacteria obtained in step 2 to 8 bottles of culture medium, and add them to 8 groups of culture medium in equal proportions, with a bacterial concentration of 2×10 7 cells / ml, cultured for 24 days in a shaker at 30°C and 180 rpm. The supernatant was collected every 3 days for analysis.

[0043] Step 4: Leaching parameters, including determination of total copper and total iron concentrations in the leachate solution, determination of attached bacterial concentrations, extraction and determination of extracellular polymeric substances (EPS), and mineral characterization, were evaluated. A 2 mL sample was centrifuged at 3000 rpm for 6 minutes to separate the bacterial solution from the mineral. The free bacterial layer above was removed, and the mineral layer below was filled to 2 mL with sterile 9K solution. After vortexing for 20 minutes, the sample was centrifuged at 3000 rpm for 6 minutes to separate the adsorbed microorganisms from the mineral. The adsorbed microorganisms were counted using a hemocytometer. Extraction and determination of extracellular polymeric substances: After 24 days of incubation, the culture was centrifuged at 10,000 rpm and 4°C for 10 minutes. The supernatant was collected and aseptically filtered through a 0.22 μm pore size filter to eliminate any residual bacteria. The resulting supernatant contained EPS. Polysaccharide determination was performed using glucose as the standard. 300 μL of sample was mixed with 900 μL of anthrone sulfate in an EP tube and placed in a constant temperature water bath at 98°C for 20 minutes. OD was then measured at 625 nm. Three-dimensional fluorescence characterization of extracellular polymers was performed using a Hitachi F-7000 fluorescence spectrophotometer (Hitachi Scientific Instruments, Beijing, Japan). The excitation wavelength range was 200–600 nm, with a sampling interval of 5 nm. The emission spectrum was scanned at a scan rate of 3000 nm / min from 200–600 nm in 5 nm increments. Mineral characterization: After the leaching experiment, all solutions were filtered with neutral filter paper. The slag was washed three times with acidified water (pH = 2.0) and dried in an oven at 40°C for subsequent analysis. Changes in mineral phase, surface functional groups, and morphological characteristics after leaching were analyzed using X-ray diffractometer, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy.

[0044] The results are as follows Figure 1-9 shown. Figure 1 The results show the effect of Af and At co-culture system with different signal molecules on leaching chalcopyrite, and the iron and copper ion concentrations and pH value reflect the leaching effect of chalcopyrite. After 3 days of leaching, the total iron concentration and total copper concentration of the experimental group were higher than those of the bacterial control group. At this time, the addition of three signal molecules promoted bioleaching. On the sixth day, the iron and copper ion concentrations of the bacterial control group exceeded C 12 -HSL experimental group, C 12-HSL inhibited the leaching of chalcopyrite by the bacterial community ( Figure 1 a and b). The pH slowly dropped from 2.0 to around 1.7, and the pH fluctuated repeatedly between the experimental groups with small differences. The redox potential is mainly determined by the iron (III) / iron (II) ratio in the solution controlled by acidophilic iron (II) oxidizing bacteria. The redox potential of the sterile control group remained stable throughout, while the potential of the bacterial treatment group increased from 360mv to 570mv on the third day. The redox potential of the bacterial control group was always lower than that of the experimental group from day 0 to day 12 ( Figure 1 c and d). After 24 days, add C 14 -HSL had the highest copper leaching concentration of 1464.01 mg / L, followed by 3-OH-C 12 -HSL (1357.08 mg / L) and C 12 -HSL (1170.37 mg / L). The results showed that the effects of different signal molecules were not significantly correlated with the concentration of the signal molecules produced by the acidophilic bacteria themselves. 14 -HSL molecules have a more obvious promoting effect on the bacterial leaching of chalcopyrite.

[0045] Figure 2 The co-culture system of Af and At plus different concentrations of signal molecule C 14 -HSL leaching effect on chalcopyrite. High concentrations of signal molecules added in the early 0-3 days promoted the leaching of chalcopyrite by the bacterial community. After the sixth day, the iron and copper ion concentrations in the 0.5 μM signal molecule treatment group were always higher than those in the high concentration C 14 -HSL group and control group (including sterile control group and methanol only control group). During the leaching process, the pH slowly dropped from 2.0 to 1.7, and the redox potential rose rapidly to about 570mv on the third day. In the early 0-9 days, the pH of the treatment group with 1 and 5μM molecules was relatively high and the redox potential was relatively low ( Figure 2 c and d). After 24 days, 0.5 μM C 14 The highest copper leaching concentration was observed in -HSL (1464.01 mg / L), followed by 1 μM (1421.58 mg / L), 5 μM (1336.71 mg / L), and 0.1 μM (1156.79 mg / L). The results showed that adding 0.1-5 μM of signaling molecules before inoculation, with a signaling molecule concentration of 0.5 μM, was most beneficial for mineral leaching.

[0046] Figure 3 The results show that the signal molecule C was added to the Af and At co-culture system at different times. 14-HSL leaching effect of chalcopyrite. When the signal molecule was added on day 0, the iron and copper ion concentrations were always higher than those of the control group (including the sterile control group and the methanol-only group). When the signal molecule was added on the third day, the iron ion concentration was always consistent with the control group, but the copper ion concentration exceeded the control group on the fifteenth day, and the difference gradually increased. During the leaching process of 0-12 days, the pH slowly decreased from 2.0 to about 1.7. From 12 days to 24 days, the pH gradually stabilized. During this period, regardless of whether the signal molecule was added on day 0 or day 3, the pH of the treatment group was always lower than that of the control group ( Figure 3 c). The redox potential increased from 350 to 570 mV, and there was no significant difference between the treatment group and the control group ( Figure 3 d) Within 24 days of leaching, the leaching effect of adding signal molecules on day 0 was stronger than that of adding signal molecules on day 3. 14 -HSL molecules may always play a role. On the third day of inoculation, bacteria have initially attached to the mineral surface, C 14 -HSL did not significantly change the leaching efficiency. The results showed that the addition of C 12 -HSL, 3-OH-C 12 -HSL, C 14 -HSL, the concentrations were 0.1μM, 0.5μM, 1μM and 5μM, and the addition time was on the 0th day or the 3rd day. Under several conditions, 0.5μMC was added at the beginning of leaching. 14 -HSL has the most obvious improvement on the leaching effect of chalcopyrite in the Af and At co-culture system.

[0047] In order to study the addition of C 14 The attachment behavior of the bacterial colony on the sulfide ore at -HSL was studied, and the free and adsorbed cells were counted. Figure 4 As shown in the figure, during the leaching process, the density of free and adsorbed cells continued to increase and gradually stabilized on the 12th day. 14 There was no significant difference in the free cell density between the -HSL experimental group and the control group. 14 The adsorption cell density of the -HSL experimental group was always higher than that of the control group, and the final adsorption cell density of the experimental group was 6.78×10 9 cells / g. The results showed that adding C 14 -HSL promotes the adsorption and colonization of microorganisms on mineral surfaces.

[0048] Figure 5 The results show that the control and C 143D fluorescence spectrum of EPS from the -HSL experimental group. The 3D fluorescence scanning spectrum can be divided into four regions: Regions II and IV are associated with humic acid-like substances, and Regions I and III are associated with protein-like substances. Region I has an excitation and emission wavelength range of Ex / Em = 200-250 / 280-380 nm, which is the region where the fluorescence peak of tyrosine-like proteins is distributed. Region II has an excitation and emission wavelength range of Ex / Em = 200-250 / 380-600 nm, corresponding to the fluorescence peak of fulvic acid-like substances. Region III corresponds to the fluorescence peak of tryptophan-like substances, with an excitation and emission wavelength range of Ex / Em = 250-350 / 280-380 nm. The humic acid-like fluorescence peak is located in Region IV, with an excitation and emission wavelength range of Ex / Em = 250-500 / 380-540 nm. The EEM spectrum of EPS of the mixed bacteria in the control group has two obvious peaks, namely Peak A (Ex / Em=210.0nm / 475.0nm) and Peak B (Ex / Em=445.0nm / 520.0nm). 14 The EEM spectrum of EPS of mixed bacteria cultured in the -HSL experimental group also has two peaks, namely Peak C (Ex / Em=205.0nm / 475.0nm) and Peak D (Ex / Em=455.0nm / 515.0nm). Among them, Peak A and C belong to region II and are fulvic acid-like compounds; Peak B and D are located in region IV and are characteristic peaks of humic acid-like compounds. Therefore, C 14 The EPS of the mixed bacteria in the -HSL experimental group contained fulvic acid-like compounds and humic acid-like compounds, and the control group also contained these two types of compounds. The fluorescence intensity showed that compared with the control group, C 14 The content of fulvic acid-like compounds and humic acid-like compounds in the EPS of the -HSL experimental group increased significantly. Studies have shown that fulvic acid contains hydrophobic aromatic rings connected by carbon chains of different functional groups, including carboxyl, carbonyl, amide, etc. Therefore, compared with the control group, C 14 The EPS in the -HSL treatment group contained humic acid-like compounds, which resulted in stronger hydrophobicity and hydrophobic interactions, which may be due to the presence of C 14 -One of the reasons why the bacterial flora in the HSL experimental group had a greater adsorption capacity on the mineral surface.

[0049] In order to further reveal the effect of QS signal molecules on the leaching process, the control group and C 14 -Differentiation of EPS polysaccharides and proteins in the HSL experimental group. Figure 6 The polysaccharide and protein concentrations of EPS extracted from the supernatant during bioleaching are shown. 14The EPS polysaccharide concentration in the -HSL experimental group was 445.59 μg / ml, which was 18% higher and showed a significant difference (p=0.008<0.05). 14 The EPS protein concentration of the -HSL experimental group was 48.81 μg / ml, which was 38% higher than that of the control group, with a significant difference (p=0.016<0.05). The increase in polysaccharide content facilitates bacterial attachment to the mineral surface, thereby promoting the dissolution of the mineral. The anionic groups in the polysaccharide form Fe 3+ -EPS complex. A large amount of Fe accumulated between the mineral surface and EPS 3+ Ions can attack minerals and promote their dissolution.

[0050] Figure 7 XRD phase retrieval analysis results showed that the mineral leaching residue was mainly composed of chalcopyrite, pyrite and quartz. Compared with the chalcopyrite sample, the chalcopyrite diffraction peak of the leaching residue of the sterile control group did not weaken significantly, indicating that the dissolution of the mineral by acid leaching was limited. On the contrary, compared with the sterile control group, the chalcopyrite diffraction peak of the bioleaching group was significantly weakened, indicating that during the bioleaching process, the microbial community destroyed the chalcopyrite through oxidation, resulting in the release of a large amount of copper ions. Compared with the control group, C 14 In the XRD pattern of the leached residue of the -HSL experimental group, the characteristic peak of chalcopyrite at 52° was significantly weakened, and multiple small quartz peaks appeared.

[0051] In order to better understand the mineral dissolution process, Fourier Transform Infrared (FTIR) spectroscopy was used to systematically study the effects of acid leaching and C addition on the mineral dissolution process. 14 - Changes in surface functional groups of leached residues caused by bioleaching under HSL conditions ( Figure 8 ). 3434.8~3424.13cm -1 The fluctuation peak position within the range can be corresponding to the υ stretching vibration of the -OH bond, which mainly exists in phenol, alcohol hydroxyl group and polysaccharide. -1 The adsorption peak is attributed to the stretching vibration of amides I and II in the protein. 14 After -HSL, the peak values ​​of the functional groups on the surface of the leached residue mostly increased. In addition, at 1187cm -1 and 1086cm -1 The adsorption peak at can be attributed to SO4 2- γ3 bending vibration; 1020cm -1 The adsorption peak at belongs to SO4 2- γ1 bending vibration; 627cm -1 The adsorption peak at belongs to SO4 2- γ4 stretching vibration. 512 and 475 cm-1 The above band is the typical adsorption peak of potassium iron vanadium. As can be seen from the figure, C 14 The -HSL experimental group has obvious yellow potassium iron vanadium structure, which indicates that C 14 -HSL accelerates the formation of passivation film. In addition, 798cm -1 The small peak at 420cm is mainly attributed to the bending vibration of the Si-O-Si tetrahedral bridge bond in quartz. -1 The peak at 420 cm in bioleaching residue is caused by the stretching vibration of polysulfides and disulfides present in chalcopyrite. -1 The bands have almost disappeared, indicating that the chalcopyrite has been oxidized and dissolved by bacteria.

[0052] The surface morphology of untreated chalcopyrite, bioleaching residue and acid leaching residue was observed by SEM ( Figure 9 ), the following results were found: the surface of the untreated chalcopyrite was clean and smooth ( Figure 9 a) In the sterile control group, the mineral surface was almost smooth and dense, but with some debris present, indicating that acid leaching had a weak ability to damage the mineral. However, after microbial treatment, the mineral surface showed significant changes, with corrosion pits forming, indicating that the mineral was significantly dissolved under the action of bacteria. These corrosion pits provided a place for microbial adsorption, facilitating further bacterial utilization of the mineral. The corrosion effect was particularly pronounced at the mineral scratches. In addition, when no C was added, the mineral surface was significantly altered, with corrosion pits forming, indicating that the mineral was significantly dissolved under the action of bacteria. 14 -HSL, only a few signs of corrosion were detected. 14 In the presence of -HSL, larger corrosion pits appeared on the surface of chalcopyrite, indicating that the surface of chalcopyrite was strongly corroded. 14 The addition of -HSL can promote the corrosion of chalcopyrite in the co-culture system.

[0053] In summary, the experimental results show that

[0054] (1) Add the following types: C 12 -HSL, 3-OH-C 12 -HSL, C 14 -HSL, the concentrations were 0.1μM, 0.5μM, 1μM and 5μM, and the addition time was at the beginning of leaching or after leaching for 72h. Under different conditions, 0.5μMC was added at the beginning of leaching. 14 -HSL has the best leaching effect on chalcopyrite leaching in the Af and At co-culture system.

[0055] (2) Add C 14-HSL promoted the attachment of bacteria in the Af and At co-culture system, promoted the production of EPS, and increased the concentrations of polysaccharides and fulvic acid in EPS. The increase of EPS in the bioleaching system was beneficial to promoting mineral dissolution.

[0056] (3) XRD, FTIR and SEM analysis results show that the addition of C 14 -HSL causes the chalcopyrite diffraction peak to weaken and the peak related to EPS to enhance, which promotes the formation of passive film and more obvious corrosion pits appear on the mineral surface.

[0057] Comparative Example 1:

[0058] Before inoculating the mixed bacteria, the quorum sensing signal molecule C was not added to the 9k culture medium. 14 -HSL, and the rest is the same as in Example 1.

[0059] The results showed that starting from the third day of leaching, the concentrations of iron and copper ions in the solution were always lower than those in Example 1, in which 0.5 μM signal molecules were added. On the 24th day of leaching, the concentrations of iron and copper ions in the solution of Comparative Example 1 were between 1200 and 1300 mg / L. 14 -HSL can significantly improve the leaching efficiency of chalcopyrite by acidophilic bacteria Af and At.

Claims

1. C 14 -HSL regulates the method for acidophilic bacteria leaching, the C 14 -HSL molecular formula is C 18 H 33 NO3; Mineral types are: chalcopyrite; The acidophilic bacteria are: mesophilic bacteria Thiobacillus ferrooxidans and Acidithiobacillus thiosulfuroxidans; C 14 -HSL was added at a concentration of 0.4-0.6 μM; After the 9K culture medium with the mineral sample was stabilized for 72 h, C 14 -HSL was added to the stable 9K medium; then the two acidophilic bacteria were added in equal proportion to the medium with C 14 -HSL stable 9K medium; The leaching system temperature was 28-30°C, pH 1.5-2.0, and the bacterial inoculum size was 2×10 7 -2.5×10 7 / mL, slurry concentration: 1.5-2.5%, leaching time: 22-26 days, rotation speed: 150-180rpm.

2. The method according to claim 1, characterized in that The specific steps include: Step 1: Weigh 2 g of chalcopyrite passed through a 200-mesh sieve into a 250 mL conical flask, add 100 mL of 9k medium to form a leaching system with a slurry concentration of 2%, and adjust the pH with 10% sulfuric acid. After 72 hours, the pH stabilizes to 2.0 to obtain 9k medium; Step 2: The mesophilic bacteria Thiobacillus ferrooxidans and Acidithiobacillus thiooxidans were cultured separately in a 9K medium containing divalent iron, wherein the composition of the medium was 3 g / L (NH4)2SO4, 0.5 g / L MgSO4·7H2O, 0.5 g / L K2HPO4, 0.1 g / L KCl, and 0.01 g / L Ca(NO3)2; the initial pH of the medium was adjusted to 2.0 with 10% H2SO4, and the amounts of substrates added were 44.7 g / L FeSO4·7H2O, 10 g / L sulfur powder, 2% chalcopyrite, and 2% pyrite, respectively; the culture was carried out in a shaker at 30°C and 180 rpm, and a bacterial culture sample was taken when the culture reached mid-logarithmic phase; Step 3: Add C to the 9k medium in step 1 14 -HSL molecules to a concentration of 0.5 μM, and then the two bacteria obtained in step 2 were added to the culture medium in equal proportions, with a bacterial concentration of 2×10 7 / mL, culture for 24 days, place in a shaker at 30℃, 180rpm.

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