Method for bioleaching lithium in lithium-containing silicate ore by using amino acid

Abstract

The invention discloses a method for biologically leaching lithium in lithium-containing silicate ore by using amino acid, which belongs to the technical field of biological metallurgy, and comprises the following steps: pretreating lepidolite to obtain lepidolite mineral powder, culturing an ore leaching strain in a culture medium, adding the lepidolite mineral powder for domestication, centrifuging a leaching solution, and collecting the domesticated ore leaching strain, thereby obtaining the lithium-containing silicate ore. Preparing a biological leaching system, inoculating the domesticated mineral leaching strain into the biological leaching system, adding glycine, and leaching to obtain a leaching solution. The method is simple in required equipment, mild in reaction condition, low in cost and environment-friendly, and glycine is low in price and easy to obtain.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bio-metallurgy, and more particularly to a method for bio-leaching lithium from lithium silicate ore by using amino acid. BACKGROUND

[0002] Lepidolite belongs to a kind of key lithium silicate minerals, and is an important raw material for obtaining lithium resources. At present, the commonly used methods for extracting lithium from lepidolite include wet process, sulfuric acid (salt) method, limestone sintering method and chlorination roasting method. However, these traditional methods usually have defects such as high energy consumption, high cost and significant environmental pollution. Compared with the traditional methods, bio-leaching technology as a new type of environmentally friendly process has gradually attracted attention due to its advantages such as mild reaction conditions, low energy consumption, simple process and environmental protection. This technology can efficiently extract valuable elements from low-grade ores with the help of microorganisms, and has become one of the research hotspots in the field of metallurgy in recent years.

[0003] However, there are still some problems in the bio-leaching technology when dealing with lepidolite ore, such as low leaching efficiency, which seriously restricts the popularization and application of the technology in industrial scale.

[0004] In view of the above problems, the present application provides a method for enhancing bio-leaching of lepidolite by using amino acid. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a method for bio-leaching lithium from lithium silicate ore by using amino acid, and to improve the extraction efficiency of lithium from lepidolite.

[0006] The technical solution adopted by the present application to solve the technical problem is to provide a method for bio-leaching lithium from lithium silicate ore by using amino acid, comprising the following steps: S1: pretreating lepidolite to obtain lepidolite ore powder; S2: selecting a leaching strain and culturing it in a culture medium, adding lepidolite ore powder for domestication, and collecting the domesticated leaching strain by centrifuging the leaching solution; S3: preparing a bio-leaching system, inoculating the domesticated leaching strain into the bio-leaching system, adding amino acid, and leaching to obtain a leaching solution; S4: detecting the concentration of Li+ in the leaching solution; S5: centrifuging and dehydrating the leaching solution to obtain a sample, and analyzing it. In this embodiment, glycine is added as a strengthening additive in the bio-leaching system in step S3.

[0007] In this embodiment, specifically, the concentration of glycine added in the lepidolite leaching system in step S3 is 0.5-5 g / L.

[0008] In the embodiment, specifically, the pretreatment process in step S1 is grinding and sieving the lepidolite ore to obtain lepidolite ore powder, and then sterilizing the lepidolite ore powder in a high-pressure steam sterilization pot.

[0009] In the embodiment, specifically, the leaching strain selected in step S2 is Acidithiobacillus ferrooxidans.

[0010] In the embodiment, specifically, the culture medium for domesticating the strain in step S2 is a 9K culture medium, and when the strain grows in the culture medium to a cell concentration of more than 1.0×107 cells / mL in the logarithmic growth phase, the strain can be used as a leaching strain.

[0011] In the embodiment, specifically, the 9K culture medium is composed of A liquid and B liquid, the components of the A liquid include 3.0 g / L ammonium sulfate, 0.1 g / L potassium chloride, 5.0 g / L magnesium sulfate heptahydrate, 5.0 g / L potassium dihydrogen phosphate, 5.0 g / L calcium nitrate, and the pH is adjusted to 1.8-2.0; the B liquid includes 10 g / L elemental sulfur, and the pH is adjusted to 1.8-2.0, and 1% (wt%) lepidolite ore slurry is added.

[0012] In the embodiment, specifically, in step S3, the inoculation amount of the leaching strain into the bioleaching system is 1.0×108-1.0×109 cells / mL.

[0013] In the embodiment, specifically, in step S3, the concentration of the lepidolite ore slurry in the bioleaching system is 10 g / L.

[0014] In the embodiment, specifically, in step S3, the bioleaching system is placed in a shaker for leaching, the pH of the bioleaching system is 1.8-2.0, the rotation speed of the shaker is 160 rpm, the leaching temperature is 30°C, and the leaching time is 20 d.

[0015] In the embodiment, specifically, in step S3, at least one of sulfuric acid and hydrochloric acid is used as a pH adjuster for the bioleaching system.

[0016] The method for bioleaching lithium from lithium silicate ore by using amino acid provided by the application comprises the following steps: BRIEF DESCRIPTION OF DRAWINGS

[0017] The application will be further described below in combination with the drawings and examples.

[0018] In the drawings: Figure 1 is the XRD pattern of the lithium mica ore in Example 1; Figure 2 is the 3D-EEM fluorescence spectrum of the lithium mica obtained in Example 1 and Comparative Example 1 without adding glycine (a) and adding 1 g / L of glycine (b); Figure 3 is the surface morphology of the leaching residue of the lithium mica obtained in Example 1 and Comparative Example 1 without adding glycine (a), without adding glycine (b) and adding 1 g / L of glycine (c); Figure 4 is the change trend chart of the Li+ concentration in the leaching system solution of the lithium mica obtained in Example 1 and Comparative Example 1 without adding glycine (a) and adding 1 g / L of glycine (b). + Concentration. DETAILED DESCRIPTION

[0019] In order to make the technical problems to be solved by the application, the technical solutions and beneficial effects clearer, the application will be described in detail in combination with the drawings. The drawings are simplified schematic diagrams, and only schematically illustrate the basic of the application, and therefore only show the structures related to the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0020] The application provides a method for bioleaching lithium from lithium silicate ore by using amino acid, comprising the following steps: S1: pretreating lithium mica to obtain lithium mica powder, grinding and sieving the lithium mica ore to a particle size of less than 0.075 mm, and placing the sieved ore powder in a high-pressure steam sterilization pot, sterilizing at 121℃ and 0.1MPa for 20min to remove the bacteria attached to the surface of the ore powder and avoid interfering with the growth and domestication of the subsequent ore leaching strain.

[0021] S2: Selecting Acidithiobacillus ferrooxidans as leaching strain, culturing in 9K medium, centrifuging leaching liquid to collect domesticated leaching strain; specifically, when the strain grows in the medium to the logarithmic growth phase with cell concentration exceeding 1.0×107 cells / mL, it can be used as leaching strain.

[0022] Specifically, the composition of the 9K medium is divided into A liquid and B liquid, the components of the A liquid include 3.0 g / L ammonium sulfate, 0.1 g / L potassium chloride, 5.0 g / L magnesium sulfate heptahydrate, 5.0 g / L potassium dihydrogen phosphate, and 5.0 g / L calcium nitrate, and the B liquid includes 10 g / L elemental sulfur.

[0023] Specifically, the preparation process of the 9K medium is as follows: Preparation of A liquid, pour deionized water into a beaker, add reagents in the order of ammonium sulfate, potassium chloride, magnesium sulfate heptahydrate, potassium dihydrogen phosphate, calcium nitrate, slowly add concentrated sulfuric acid with a pipette, stir while adding, and monitor in real time with a pH meter, adjust the pH of the A liquid to 1.8~2.0, transfer the A liquid with adjusted pH to a 1L volumetric flask, rinse the beaker with a small amount of deionized water for 2~3 times, pour the rinse liquid into the volumetric flask, finally add deionized water to 1L, shake well and reserve.

[0024] Preparation of B liquid, take a beaker and add 100mL deionized water, add 1~2 drops of concentrated sulfuric acid, add 1.0g of powdered elemental sulfur, stir quickly with a glass rod for 10~15 minutes to evenly disperse the elemental sulfur in the water, add 1% by weight of lithium mica ore powder (i.e. 1g of sterilized lithium mica ore powder is added to 100mL of B liquid) to the B liquid, stir well and reserve.

[0025] Put the A liquid into a high-pressure steam sterilization pot, set the temperature to 121℃ and the pressure to 0.1MPa, sterilize for 20 minutes, take out the sterilized A liquid, place it in a sterile operation table or ultra-clean table, and naturally cool it to below 40℃, slowly pour the pretreated B liquid into the cooled A liquid in a sterile environment, shake gently, at this time the medium is a white suspension, which can be immediately used for microbial inoculation.

[0026] S3: Adjust the pH of the 10 g / L lithium mica ore slurry to 1.8~2.0, use a sterile pipette to suck the active leaching bacteria liquid and slowly drop it into the above lithium mica ore slurry, add amino acid to strengthen leaching, place the bioleaching system (Erlenmeyer flask) in a 30℃, 160rpm shaker for leaching, leach for 20d, and take samples regularly to obtain leaching liquid. Specifically, glycine is selected as a strengthening agent added to the bioleaching system.

[0027] Specifically, the concentration of glycine added to the lepidolite leaching system was 0.5–5 g / L, and the inoculum size of the leaching strain was 1.0 × 10⁻⁶ g / L. 8 ~1.0×10 9 cells / mL.

[0028] Specifically, at least one of sulfuric acid and hydrochloric acid is used as a pH adjuster in the bioleaching system.

[0029] S4: Detection of Li in leachate + The concentration of Li in the leachate was measured every two days using a graphite furnace atomic absorption spectrometer (AAS). + The concentration changes were measured, and the pH and redox potential of the bacterial leaching system solution were measured using a pH meter (PHS-3C).

[0030] S5: Centrifuge and dehydrate the leachate to obtain a sample for analysis; Specifically, after the bioleaching was completed, the solid-liquid mixture at the bottom of the leaching conical flask was removed and injected into a centrifuge tube. The tube was then centrifuged at 8600 rpm for 15 min using a refrigerated centrifuge, and the solid residue at the bottom of the centrifuge tube was retained. The residue was then fixed by soaking it in 2.5% glutaraldehyde for 2 h. Subsequently, it was dehydrated in gradients of 25%, 50%, 75%, and 99% ethanol solutions for 10 min each. The dehydrated solid residue was then dried in a freeze dryer. Finally, the solid sample was stored and analyzed for surface morphology, phase composition, and elemental composition.

[0031] Example 1: S1: Take lepidolite ore, grind and sieve it to obtain lepidolite powder with a particle size of less than 0.075mm, and sterilize the lepidolite powder using a high-pressure steam sterilizer. S2: Autotrophic *Acidithiobacillus ferrooxidans* was selected as the leaching strain. The bacteria were acclimated in 9K medium with 1% (by weight) lepidolite slurry, achieving a acclimation cell concentration exceeding 1.0 × 10⁻⁶ cells / day. 7 When the concentration of cells / mL is reached, collect by centrifugation. S3: Based on an inoculation dose of 1.6 × 10⁻⁶ 7 The acclimatized *Acidithiobacillus ferrooxidans* was inoculated into a leaching system with a lithium mica slurry density of 10 g / L and a glycine addition of 1 g / L. The pH of the leaching system was adjusted to 2.0 using 0.01 mol / L sulfuric acid, and leaching was carried out on a shaker at 160 rpm and 30 ℃ for 20 days. S4: Every two days, Li in the leachate is analyzed using a graphite furnace atomic absorption spectrometer (AAS). +The concentration change was determined, and the pH and redox potential of the solution in the bacterial leaching system were determined using a pH meter (PHS-3C); S5: After the bioleaching was completed, the solid-liquid coexisting matter at the bottom of the leaching conical flask was taken out and injected into a centrifuge tube, and a refrigerated centrifuge was used for centrifugation at a speed of 8600 rpm for 15 min, and the solid residue at the bottom of the centrifuge tube was retained, soaked in 2.5% glutaraldehyde for 2 h for fixation, and then dehydrated with 25%, 50%, 75%, and 99% ethanol solutions for 10 min, respectively, the dehydrated solid residue was placed into a freeze dryer for drying, and finally the solid sample was well preserved for surface morphology, phase, and element composition analysis.

[0032] Comparative Example One S1: Lithium mica ore was ground and sieved to obtain lithium mica ore powder with a particle size of less than 0.075 mm, and a high-pressure steam sterilization pot was used to sterilize the lithium mica ore powder; S2: Autotrophic Acidithiobacillus ferrooxidans was selected as the leaching strain, and the bacteria were domesticated in a 9K medium added with 1% lithium mica slurry by weight, and the domesticated cell concentration was more than 1.0 x 107 cells / mL, which was collected by centrifugation; S3: The domesticated Acidithiobacillus ferrooxidans was inoculated into lithium mica slurry with a density of 10 g / L at an inoculation amount of 1.6 x 107 cells / mL, without adding glycine, and the pH of the leaching system was adjusted to 2.0 using sulfuric acid with a concentration of 0.01 mol / L, and the leaching was carried out on a shaker at a speed of 160 rpm and a temperature of 30°C for 20 days; S4: The concentration change of Li+ in the leaching solution was determined every two days using a graphite furnace atomic absorption spectrometer (AAS), and the pH and redox potential of the solution in the bacterial leaching system were determined using a pH meter (PHS-3C); S5: After the bioleaching was completed, the solid-liquid coexisting matter at the bottom of the leaching conical flask was taken out and injected into a centrifuge tube, and a refrigerated centrifuge was used for centrifugation at a speed of 8600 rpm for 15 min, and the solid residue at the bottom of the centrifuge tube was retained, soaked in 2.5% glutaraldehyde for 2 h for fixation, and then dehydrated with 25%, 50%, 75%, and 99% ethanol solutions for 10 min, respectively, the dehydrated solid residue was placed into a freeze dryer for drying, and finally the solid sample was well preserved for surface morphology, phase, and element composition analysis.

[0033] From Figure 1 It can be seen that the main phase composition of the lithium mica ore contains lepidolite and muscovite, and a small amount of silicon dioxide.

[0034] Glycine is one of the simplest and cheapest amino acids, possessing environmental safety, stability, and enzymatic degradability. Depending on the pH of the solution, glycine can exist in three forms: cationic (…). + H3NCH2COO), zwitterions ( + In acidic solutions (pH < 2.35), the cationic form of glycine (H3NCH2COO-) or anion (H2NCH2COO-) is dominant. Due to its strong ability to form complexes, glycine can construct 1:1 and 1:2 complexes with the help of carboxyl or amino groups and rare earth elements.

[0035] from Figure 2 It was found that after adding glycine, the protein content in the leaching system showed a significant increase. This is because glycine is one of the basic building blocks of proteins and participates in the protein folding and peptide bond formation process. In addition, the side chains of glycine are small, so it is more flexible and can construct more complex proteins in three-dimensional space. This indicates that glycine plays a significant promoting role in the bioleaching process of lepidolite.

[0036] Depend on Figure 3 It can be seen that, compared with the absence of glycine, the erosion and fragmentation of the lepidolite surface is more obvious after the addition of glycine. Therefore, adding glycine during the bioleaching process of lepidolite can increase the leaching concentration of lithium in lepidolite.

[0037] from Figure 4 It was found that when the glycine concentration was 0 g / L, the lithium leaching concentration in lepidolite was 8.5 mg / L, with a leaching rate of 4.81%; when the glycine concentration was 1 g / L, the lithium leaching concentration in lepidolite was 10.7 mg / L, with a leaching rate of 6.05%. The bioleaching system with added glycine showed a leaching rate increase of 25.8% compared to the system without added glycine. On day 12, the leaching rate of lepidolite with and without added glycine was not significantly different, but the difference became significant after day 12, and the rate of increase remained high until day 20.

[0038] The beneficial effects of this invention's method for bioleaching lithium from lithium-containing silicate ores using amino acids are as follows: 1. The addition of glycine to the leaching system resulted in a significant increase in protein content. Since glycine is one of the basic building blocks of proteins, it participates in protein folding and peptide bond formation. Furthermore, the small size of glycine's side chains allows for greater flexibility, enabling the construction of more complex proteins in three-dimensional space. This indicates that glycine plays a crucial promoting role in the bioleaching process of lepidolite.

[0039] 2. Glycine acts as a reinforcing agent, providing more growth elements for bacteria, promoting the increase of bacterial biomass, and thus enhancing the leaching effect of bacteria adsorption, organic acid etching and complexation, and bacterial growth characteristics, thereby improving the leaching rate of Li+. Under the influence of glycine, the leaching concentration of Li in lepidolite is increased by 25.8% compared with the control group without adding glycine.

[0040] 3. After adding glycine, the decrease in diffraction peaks of leaching residues is significantly greater than that of pure bioleaching system. This indicates that the chemical composition of the ore surface has changed, confirming that the addition of glycine can promote the bioleaching of lepidolite.

[0041] 4. The present application uses glycine to enhance the bioleaching of lepidolite. This method requires simple equipment, has mild reaction conditions, low cost, is environmentally friendly, and glycine is cheap and easy to obtain.

[0042] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0043] It should be noted that the terms "first", "second", and the like, as used in the specification and in the claims, are intended to modify a particular aspect of the subject matter described and are not intended to "limit" the aspect according to the specific sequence, unless otherwise indicated by the context.

[0044] Based on the above ideal embodiments according to the present application, the above description, relevant personnel can make various changes and modifications without deviating from the scope of the present application. The technical scope of the present application is not limited to the contents of the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. The method for bioleaching lithium from lithium-containing silicate ore using amino acids according to claim 1, characterized in that, Includes the following steps, S1: Pre-treat lepidolite to obtain lepidolite powder; S2: Select leaching strains, culture them in a culture medium, add lepidolite powder for domestication, and collect the domesticated leaching strains by centrifuging the leachate. S3: Prepare a bioleaching system by inoculating the domesticated mineral leaching strains into the bioleaching system, adding glycine, and leaching to obtain a leachate; S4: Detection of Li in leachate + concentration; S5: Centrifuge and dehydrate the leachate to obtain a sample for analysis.

2. The method for bioleaching lithium from lithium-containing silicate ores using amino acids according to claim 1, characterized in that, The concentration of glycine added to the lepidolite leaching system in step S3 is 0.5–5 g / L.

3. The method for bioleaching lithium from lithium-containing silicate ore using amino acids according to claim 1, characterized in that, The pretreatment process in step S1 involves grinding and sieving the lepidolite ore to obtain lepidolite powder, ensuring that the particle size of the lepidolite powder is below 0.075 mm, and then sterilizing it in a high-pressure steam sterilizer.

4. The method for bioleaching lithium from lithium-containing silicate ores using amino acids according to claim 1, characterized in that, The leaching strain selected in step S2 is Acidithiobacillus ferrooxidans.

5. The method for bioleaching lithium from lithium-containing silicate ores using amino acids according to claim 1, characterized in that, In step S2, the culture medium for acclimatizing the strain is 9K medium. When the strain grows to the logarithmic growth phase in the medium, the cell concentration exceeds 1.0 × 10⁻⁶. 7 When the concentration of cells / mL is low, it can be used as a leaching bacteria.

6. The method for bioleaching lithium from lithium-containing silicate ores using amino acids according to claim 5, characterized in that, The 9K culture medium is composed of solution A and solution B. Solution A consists of 3.0 g / L ammonium sulfate, 0.1 g / L potassium chloride, 5.0 g / L magnesium sulfate heptahydrate, 5.0 g / L potassium dihydrogen phosphate, and 5.0 g / L calcium nitrate, with the pH adjusted to 1.8-2.

0. Solution B consists of 10 g / L elemental sulfur, with the pH adjusted to 1.8-2.0, and 1% by weight of lepidolite slurry added.

7. The method for bioleaching lithium from lithium-containing silicate ore using amino acids according to claim 1, characterized in that, In step S3, the inoculum size of the leaching strain in the bioleaching system is 1.0 × 10⁻⁶. 8 ~1.0×10 9 cells / mL.

8. The method for bioleaching lithium from lithium-containing silicate ores using amino acids according to claim 1, characterized in that, In step S3, the concentration of lepidolite in the bioleaching system is 10 g / L.

9. The method for bioleaching lithium from lithium-containing silicate ore using amino acids according to claim 1, characterized in that, In step S3, the bioleaching system is placed in a shaker for leaching. The pH of the bioleaching system is 1.8 to 2.0, the shaker speed is 160 rpm, the leaching temperature is 30℃, and the leaching time is 20 days.

10. The method for bioleaching lithium from lithium-containing silicate ore using amino acids according to claim 1, characterized in that, In step S3, at least one of sulfuric acid and hydrochloric acid is used as a pH adjuster for the bioleaching system.

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