Method for leaching nickel-cobalt-copper sulfide ore under nearly neutral pH (Potential of Hydrogen) condition

Abstract

The invention discloses a method for leaching nickel-cobalt-copper sulfide ore under a near-neutral pH condition. The method comprises the following steps: domesticating and culturing microorganisms under the near-neutral pH condition; construction of a near-neutral biological leaching system (an organism-ligand leaching system); leaching the nickel-cobalt-copper sulfide ore; and finally, leaching liquid containing nickel, cobalt, copper and other valuable metal ions is obtained. According to the method, the pH value of a near-neutral microorganism-ligand leaching system is 5-9, and the pollution risk and the repair problem of a traditional biological leaching acid site are avoided. Meanwhile, biological oxidation avoids the use of a chemical oxidizing agent for chemical oxidation leaching. In addition, the near-neutral environment of the method effectively overcomes the problems that the acid consumption amount is large, the permeability of a leaching pile body is deteriorated and the like when a conventional acid system is used for leaching nickel-cobalt-copper sulfide ore with the high content of basic gangue such as calcium and magnesium, and finally selective efficient extraction of valuable elements is achieved. According to the method for leaching the nickel-cobalt-copper sulfide ore under the nearly neutral pH condition, used equipment is simple, operation is easy, environment friendliness is achieved, and industrial application and popularization can be achieved easily.

Description

Technical Field

[0001] The invention belongs to the field of mineral processing and hydrometallurgy, and in particular relates to a method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions. Background Art

[0003] In my country, nickel, cobalt and copper usually coexist in a complex and close manner, and the content of calcium-magnesium alkaline gangue minerals is high, forming high-calcium-magnesium low-grade nickel-cobalt-copper sulfide ores, the development and utilization of which is of great significance. High-calcium-magnesium low-grade nickel-cobalt-copper sulfide ores generally have the characteristics of large oxidation rate changes (oxygen-sulfur mixture), high binding rate, large mud content, many mineral types, and fine embedded particle size. For such ores, the traditional flotation-pyrometallurgical route is extremely difficult to achieve economical, clean and efficient utilization due to poor technical indicators, high production costs, complex process flow, environmental pollution and other problems.

[0004] Biometallurgy (bioleaching) mainly involves leaching valuable metal elements through the direct and indirect action of acidophilic microorganisms (pH is usually less than 2) under relatively mild conditions such as normal temperature and pressure, and then separating and recovering them from the leachate. Biometallurgy is of great significance in the economic, clean and efficient utilization of low-grade complex mineral resources due to its advantages in low cost, low carbon and green environmental protection. However, for high-calcium and low-grade nickel-cobalt-copper sulfide ores, traditional acidic bioleaching requires a large amount of sulfuric acid to pre-acidify the ore in advance. At the same time, the large amount of dissolution of alkaline gangue can easily lead to the continuous deterioration of the permeability of the leaching pile, the passivation of the valuable mineral leaching interface, and the excessive calcium and magnesium content of the leachate, which are difficult to overcome bottlenecks and challenges. In addition, the acidic sites subsequent to acidic bioleaching face the risk of soil, surface water and groundwater pollution, which require a lot of manpower and material resources for repair.

[0005] At the same time, the existing reports on bioleaching under moderately alkaline conditions mostly use heterotrophic microorganisms to utilize the organic acids and biological ligands produced by their metabolism for leaching. However, the organic acids have a weak destructive effect on the ore structure, and the output of biological ligands is extremely low and the coordination effect on the target metal ions is limited, resulting in extremely low leaching rates and no commercial application value. Summary of the invention

[0006] The object of the present invention is to provide a method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions. The biological leaching method based on the principle of biological oxidation-complexation / coordination synergistic reaction can cleanly and efficiently leach nickel-cobalt-copper ore, avoiding the subsequent site pollution risk of traditional acidic biological leaching. At the same time, the method of the present invention also avoids the large-scale dissolution of alkaline gangue during the leaching process.

[0007] The present invention provides a method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions, comprising the following steps:

[0008] S1. Inoculating the microorganisms into a composite culture medium containing nickel-cobalt-copper sulfide ore powder for acclimatization and culture, and centrifuging to obtain bacterial sludge;

[0009] S2. The bacterial sludge obtained in step S1 is inoculated into a composite medium containing reduced sulfur for amplification and culturing, and filtered to obtain a bacterial suspension;

[0010] S3. Add the ligand to the bacterial suspension obtained in step S2, adjust the pH, and obtain a microorganism-ligand extractant;

[0011] S4. The nickel-cobalt-copper sulfide ore is mixed with the microorganism-ligand leaching agent obtained in step S3, and biological leaching is performed. After the biological leaching is completed, solid-liquid separation is performed to obtain a leachate containing nickel-cobalt-copper valuable metal ions.

[0012] Further, in step S1, the microorganisms include one or more of autotrophic, heterotrophic or facultative sulfur-oxidizing microorganisms that prefer near-neutral pH conditions;

[0013] Among them, the autotrophic microorganisms include Thiomicrorhabdus, Halothiobacillus, Sulfurimonas, Mesorhizobium, Thiobacillus, Thermithiobacillus, and Thiomicrospira microorganisms;

[0014] Heterotrophic microorganisms include Bacillus, Citreicella, and Limnobacter.

[0015] Facultative microorganisms include microorganisms of the genera Thioclavus and Thiomonas.

[0016] The microorganism can oxidize reduced sulfur substances such as thiosulfate, sulfide, elemental sulfur or tetrasulfate under the conditions of pH 4 to 10.5, temperature of -1 to 45°C and salinity of 0 to 100 g / L NaCl.

[0017] Preferably, the culture conditions of the microorganism are: pH 5-9, temperature 25-35°C, and salinity 20-35 g / L NaCl.

[0018] The matrix of the composite culture medium containing nickel-cobalt-copper sulfide ore powder includes a carbon source, a nitrogen source, an inorganic salt, vitamins, and nickel-cobalt-copper sulfide ore powder; wherein the amount of the carbon source is 10 to 100 mmol / L in terms of carbon content, the amount of the nitrogen source is 10 to 100 mmol / L in terms of nitrogen content, and the amount of the inorganic salt satisfies that the phosphorus, potassium, magnesium, and calcium contents are 0.01 to 20 mmol / L.

[0019] The carbon source includes one or more of calcium carbonate, acetic acid, succinic acid, malic acid, lactic acid, pyruvic acid, citric acid, propionic acid, butyric acid, gluconic acid, glycolic acid, glyoxylic acid, ethanol, glycerol, mannitol, sorbitol, glucose, fructose, maltose, sucrose, L-arabinose, D-cellobiose, starch, proline, lysine, alanine, glutamic acid, glutamine, aspartic acid, asparagine, leucine, and arginine;

[0020] The nitrogen source includes one or more of bean cake powder, corn steep liquor, yeast extract, yeast extract powder, nitrate, urea, and ammonium salt;

[0021] Inorganic salts include inorganic salts in carbon sources and nitrogen sources, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tricalcium phosphate, potassium chloride, calcium nitrate, magnesium sulfate and sodium chloride;

[0022] Vitamins include biotin (vitamin H), pyridoxine (vitamin B6) and thiamine (vitamin B1), and the dosage is 10-100 μmol / L.

[0023] The content of nickel-cobalt-copper sulfide ore powder in the matrix of the composite culture medium containing nickel-cobalt-copper sulfide ore powder is 1-20 g / L.

[0024] The composite culture medium containing nickel-cobalt-copper sulfide ore powder is prepared by deionized water or artificial seawater. In particular, the artificial seawater is composed of: NaCl 26.726 g / L, MgCl 2 2.26 g / L, MgSO 4 3.248 g / L, CaCl 2 1.153 g / L, NaHCO 3 0.198 g / L, KCl 0.721g / L, NaBr 0.058g / L, H 3 BO 3 0.058g / L, Na 2 SiO 3 0.0024 g / L, Na 2 Si 4 O 9 0.0015 g / L, H 3 PO 4 0.002 g / L, Al 2 Cl6 0.013 g / L, NH 3 0.002 g / L, LiNO 3 0.0013 g / L.

[0025] The process conditions of the acclimation culture are: the culture time is 10 to 60 days, the culture temperature is 25 to 35° C., the pH is adjusted to 5 to 9 using 1 mol / L hydrochloric acid and 1 mol / L sodium hydroxide solution, the acclimation is carried out in a shaking bottle, the rotation speed is 160 to 180 rpm, and no aeration is required;

[0026] The centrifugal speed is 9000-11000 rpm and the time is 18-22 minutes.

[0027] Furthermore, in step S2, the matrix of the composite culture medium containing reduced sulfur includes a carbon source, a nitrogen source, an inorganic salt, vitamins, and a reduced sulfur substance, wherein the carbon source, the nitrogen source, the inorganic salt, the vitamins, and the configuration are the same as those of the composite culture medium containing nickel-cobalt-copper sulfide ore powder in step S1;

[0028] The reduced sulfur substance comprises one or more of sodium thiosulfate, pyrite and elemental sulfur; the content of the reduced sulfur substance in the composite culture medium containing reduced sulfur is 1-20 g / L.

[0029] The process conditions of the amplification culture are: the culture time is 1 to 10 days, the culture temperature is 25 to 35° C., 1 mol / L hydrochloric acid and 1 mol / L sodium hydroxide solution are used to adjust the pH to 5 to 9, the amplification culture is carried out in a shaking bottle, the rotation speed is 170 rpm, and no aeration is required.

[0030] The viable count of the bacterial suspension is 10 9 ~10 10 pcs / ml;

[0031] Further, in step S3, the ligand includes one or more of aspartic acid, glycine, citric acid and its salts, nitrilotriacetic acid and its salts, iminodiacetic acid and its salts, ethylenediaminetetraacetic acid and its salts, diethylenetriamine, and diethylenetriaminepentaacetic acid;

[0032] After the ligand is added, the concentration of the ligand in the solution is 1 to 50 g / L.

[0033] After mixing, adjust the pH range to 5-9;

[0034] Further, in step S4, the process conditions of the biological leaching are: liquid-solid ratio of 10: (0.1-3), leaching time of 10-60 days, leaching temperature of 25-35°C, 1 mol / L hydrochloric acid and 1 mol / L sodium hydroxide solution are used to adjust the pH to 5-9, leaching is carried out in a shaking bottle, the rotation speed is 200 rpm, and no aeration is required. Principle of the present invention:

[0035] The present invention utilizes the sulfur oxidation ability of microbial metabolic activities to destroy the lattice structure of nickel-cobalt-copper sulfide ore, and then utilizes biological metabolites and added ligands to selectively coordinate with released valuable metal ions to make them stably exist in a near-neutral solution environment. The present invention combines biological oxidation with biological or chemical ligand coordination of valuable metal ions to achieve biological leaching of metal sulfides under near-neutral conditions, avoiding the difficult-to-overcome bottlenecks and challenges such as large acid consumption in conventional acidic systems, continuous deterioration of leaching pile permeability, passivation of valuable mineral leaching interfaces, and excessively high calcium and magnesium content in the leachate, and avoids the pollution risk and remediation problems of acidic sites after leaching.

[0036] Beneficial effects of the present invention:

[0037] (1) The method of the present invention utilizes the synergistic effect of biological oxidation, biological metabolites and chemical ligands under near-neutral conditions, thereby avoiding the pollution risk and remediation problems of acidic sites after leaching;

[0038] (2) The method of the present invention realizes the selective and efficient extraction of valuable elements in nickel-cobalt-copper sulfide ores with high calcium and magnesium content and other alkaline gangue, and effectively overcomes the difficult problems of conventional acidic systems, such as large acid consumption, continuous deterioration of leaching pile permeability, passivation of valuable mineral leaching interface, and excessively high calcium and magnesium content in the leachate;

[0039] (3) The microorganisms used in the present invention are widely present in nature and have the advantages of being green, environmentally friendly and low cost;

[0040] (4) The bio-oxidation method of the present invention replaces the use of chemical oxidants, can effectively alleviate environmental pollution pressure, and achieve clean and efficient extraction of valuable elements in nickel-cobalt-copper sulfide ores;

[0041] (5) The microorganisms used in the present invention generally have a high NaCl tolerance, so seawater can be used instead of fresh water during the leaching process, which is beneficial to saving fresh water resources;

[0042] (6) The method for leaching nickel-cobalt-copper sulfide ore under near-neutral conditions of the present invention has simple equipment, simple operation, and is environmentally friendly, which is conducive to industrial promotion and application. DETAILED DESCRIPTION

[0043] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] The unit of liquid-to-solid ratio in the present invention is mL / g, and the grade is the mass fraction of the element.

[0045] The grade of the selected No. 1 nickel-cobalt-copper sulfide ore is: Ni 1.01%, Co 0.05%, Cu 1.26%, Mg 19.2%, and the grade of the selected No. 2 nickel-cobalt-copper sulfide ore is: Ni 1.69%, Co 0.07%, Cu 0.38%, Mg 15.0%. They are crushed and ground to less than 200 mesh, and 1 to 30 g are evenly taken and put into a 250 mL conical flask.

[0046] Example 1

[0047] Halothiobacillus neapolitanus MCCC 1A18420 was inoculated into a composite culture medium containing nickel-cobalt-copper sulfide ore powder prepared with deionized water, and cultured for 15 days under pH 7 conditions, and then filtered and centrifuged to obtain bacterial sludge; wherein the specific formula of the composite culture medium containing nickel-cobalt-copper sulfide ore powder prepared with deionized water is: (NH 4 ) 2 SO 4 3.0 g / L, MgSO 4 7H 2 O 0.5g / L, K 2 HPO 4 0.5 g / L, KCl 0.1 g / L, Ca(NO 3 ) 2 0.01g / L, NaCl 25g / L, yeast extract powder 0.2g / L, No. 1 mineral powder 20g / L;

[0048] The bacterial sludge was then inoculated into a composite medium containing reduced sulfur prepared by deionized water for amplification culture for 7 days, and a bacterial suspension (bacterial concentration was not less than 3.0×108 cells / mL) was obtained by filtration; wherein the specific formula of the composite medium containing reduced sulfur prepared by deionized water was: (NH 4 ) 2 SO 4 3.0 g / L, MgSO 4 7H 2 O0.5g / L, K 2 HPO 4 0.5 g / L, KCl 0.1 g / L, Ca(NO 3 )2 0.01g / L, NaCl 25g / L, yeast extract powder 0.2g / L, sodium thiosulfate 3g / L;

[0049] Add 1g of iminodiacetic acid ligand to 100mL of bacterial suspension, adjust the pH to 7 to prepare a microorganism-ligand leaching agent; then, according to the leaching liquid-solid ratio of 100:1 (No. 1 nickel-cobalt-copper sulfide ore), the ore is leached with the microorganism-ligand leaching agent, and the leaching process is carried out in a constant temperature oscillator at a temperature of 30°C and a speed of 200rpm. The leachate is collected after 20 days of leaching. The leachate is tested by ICP-AES, and the leaching rates of Ni, Co, and Cu are 80.6%, 77.1%, and 35.7%, respectively, and the leaching rate of the impurity element Mg is only 3.0%.

[0050] Example 2

[0051] The same microbial suspension as in Example 1 was used to leach the No. 2 nickel-cobalt-copper sulfide ore according to the same leaching process as in Example 1 to obtain a leachate. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 82.1%, 74.9%, and 32.3%, respectively, and the leaching rate of the impurity element Mg was only 4.0%.

[0052] Comparative Example 1

[0053] Take 100 mL of sterile culture medium, add 1 g of iminodiacetic acid ligand, adjust the pH to 7 to prepare a chemical leaching agent, and leach the ore according to the same leaching process as Example 1. The leachate is tested by ICP-AES, and the leaching rates of Ni, Co, and Cu are 40.2%, 37.4%, and 15.0%, respectively.

[0054] Comparative Example 2

[0055] 100 mL of the same microbial suspension as in Example 1 was taken without adding a ligand, and the ore was leached according to the same leaching process as in Example 1. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 0.3%, 0.01%, and 0%, respectively.

[0056] Combining the results of Example 1, Example 2, Comparative Example 1 and Comparative Example 2, we can see that the leaching effects of Example 1 and Example 2 are similar, and are significantly better than Comparative Example 1 and Comparative Example 2, indicating that the bio-ligand leaching agent composed of Naples salt sulfur bacteria combined with iminodiacetic acid ligand has a synergistic effect, and the similar effects on No. 1 and No. 2 nickel cobalt copper sulfide ores prove the stability and universality of the present bio-leaching agent.

[0057] Example 3

[0058] Citreicella thiooxidans MCCC 1A13021 and Thioclavapus pacificus MCCC 1A03188 were inoculated into a composite culture medium containing nickel-cobalt-copper sulfide ore powder prepared by artificial seawater, and cultured for 20 days under pH 7 conditions, and then filtered and centrifuged to obtain bacterial sludge; wherein the specific formula of the composite culture medium containing nickel-cobalt-copper sulfide ore powder prepared by artificial seawater is as follows: on the basis of artificial seawater, (NH 4 ) 2 SO 4 3.0 g / L, K 2 HPO 4 0.5 g / L, citric acid 5g / L, soybean cake powder 0.5g / L, No. 2 mineral powder 50g / L;

[0059] The bacterial sludge was then inoculated into a composite medium containing reduced sulfur prepared from artificial seawater for amplification culture for 7 days, and the bacterial suspension (bacterial concentration of about 3.0×10 9 The specific formula of the composite medium containing reduced sulfur prepared by artificial seawater is as follows: on the basis of artificial seawater, add (NH 4 ) 2 SO 4 3.0g / L, K 2 HPO 4 0.5 g / L, citric acid 5 g / L, soybean meal 0.5 g / L, sodium thiosulfate 3 g / L and elemental sulfur 5 g / L;

[0060] Add 1g of iminodiacetic acid ligand and 1g of sodium ethylenediaminetriacetate ligand to 100mL of bacterial suspension, adjust pH to 7 to prepare microorganism-ligand leaching agent; then, according to the leaching liquid-solid ratio of 100:2 (No. 1 nickel-cobalt-copper sulfide ore), the ore is leached with the microorganism-ligand leaching agent, and the leaching process is carried out in a constant temperature oscillator at a temperature of 35°C and a speed of 200rpm. The leachate is collected after 20 days of leaching. The leachate is tested by ICP-AES, and the leaching rates of Ni, Co, and Cu are 88.9%, 87.4%, and 40.1%, respectively, and the leaching rate of impurity element Mg is only 5.2%.

[0061] Example 4

[0062] The same microbial suspension as in Example 3 was used to leach the No. 2 nickel-cobalt-copper sulfide ore according to the same leaching process as in Example 3 to obtain a leachate. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 90.4%, 89.9%, and 45.1%, respectively, and the leaching rate of the impurity element Mg was only 4.9%.

[0063] Comparative Example 3

[0064] Take 100 mL of sterile culture medium, add 1 g of iminodiacetic acid ligand and 1 g of sodium ethylenediaminetriacetate ligand, adjust the pH to 7 to prepare a chemical leaching agent, and leach the ore according to the same leaching process as in Example 3. The leachate is tested by ICP-AES, and the leaching rates of Ni, Co, and Cu are 58.7%, 57.6%, and 35.6%, respectively.

[0065] Comparative Example 4

[0066] 100 mL of the same microbial suspension as in Example 3 was taken without adding a ligand, and the ore was leached according to the same leaching process as in Example 3. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 0.5%, 0.1%, and 0.1%, respectively.

[0067] Combining the results of Example 3, Example 4, Comparative Example 3 and Comparative Example 4, we can see that the leaching effects of Example 3 and Example 4 are similar, and are significantly better than Comparative Example 3 and Comparative Example 4, indicating that the bio-ligand leaching agent composed of sulfur-oxidizing lemon spore bacteria and Pacific sulfur-expansion bacteria combined with iminodiacetic acid ligands and sodium ethylenediaminetriacetate ligands has a synergistic effect, and the similar effects on No. 1 and No. 2 nickel-cobalt-copper sulfide ores prove the stability and universality of the bio-leaching agent. In addition, Example 3 and Example 4 show the feasibility of configuring the culture medium with seawater instead of fresh water.

[0068] Example 5

[0069] Thiomicrorhabdus sediminis MCCC 1A14511, Sulfurimonas lithotrophica MCCC 1A14739, and Citreicella thiooxidans MCCC 1A13021 were inoculated into a composite culture medium containing nickel-cobalt-copper sulfide ore powder and cultured for 20 days under pH 7.8, and then filtered and centrifuged to obtain bacterial sludge; wherein the specific formula of the composite culture medium containing nickel-cobalt-copper sulfide ore powder is: (NH 4 ) 2 SO 4 3.0 g / L, MgSO 4 7H 2 O0.5g / L, K 2 HPO 4 0.5 g / L, KCl 0.1 g / L, Ca(NO 3 ) 20.01g / L, NaCl 20g / L, acetic acid 3g / L, yeast extract 0.5g / L, No. 1 mineral powder 20g / L;

[0070] The bacterial sludge was then inoculated into a composite culture medium containing reduced sulfur for amplification culture for 7 days, and then filtered to obtain a bacterial suspension (bacterial concentration was about 2.0×109 cells / mL); wherein the specific formula of the composite culture medium containing reduced sulfur was: (NH 4 ) 2 SO 4 3.0g / L, MgSO 4 7H 2 O 0.5g / L, K 2 HPO 4 0.5 g / L, KCl 0.1 g / L, Ca(NO 3 ) 2 0.01g / L, NaCl 20g / L, acetic acid 3g / L, yeast extract 0.5g / L, elemental sulfur 10g / L

[0071] Add 2g of sodium ethylenediaminetriacetate ligand to 100mL of bacterial suspension, adjust the pH to 7.8 to prepare a microorganism-ligand leaching agent; then, according to the leaching liquid-solid ratio of 100:1 (No. 1 nickel-cobalt-copper sulfide ore), the ore is leached with the microorganism-ligand leaching agent. The leaching process is carried out in a constant temperature oscillator at a temperature of 28°C and a speed of 200rpm. The leachate is collected after 50 days of leaching. The leachate is tested by ICP-AES, and the leaching rates of Ni, Co, and Cu are 83.6%, 81.7%, and 39.9%, respectively, and the leaching rate of the impurity element Mg is only 6.3%.

[0072] Example 6

[0073] The same microbial suspension as in Example 5 was used to leach the No. 2 nickel-cobalt-copper sulfide ore according to the same leaching process as in Example 5 to obtain a leachate. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 89.7%, 87.4%, and 42.1%, respectively, and the leaching rate of the impurity element Mg was only 5.8%.

[0074] Comparative Example 5

[0075] Take 100 mL of sterile culture medium, add 2 g of sodium ethylenediaminetriacetate ligand, adjust the pH to 7.8 to prepare a chemical leaching agent, and leach the ore according to the same leaching process as in Example 5. The leachate is tested by ICP-AES, and the leaching rates of Ni, Co, and Cu are 50.3%, 51.6%, and 33.1%, respectively.

[0076] Comparative Example 6

[0077] 100 mL of the same microbial suspension as in Example 5 was taken without adding a ligand, and the ore was leached according to the same leaching process as in Example 5. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 0.6%, 0.2%, and 0.1%, respectively.

[0078] Combining the results of Example 5, Example 6, Comparative Example 5 and Comparative Example 6, we can see that the leaching effects of Example 5 and Example 6 are similar, and are significantly better than Comparative Example 5 and Comparative Example 6, indicating that the bio-ligand leaching agent composed of a mixed mixed bacteria of sediment sulfur microbacterium, inorganic nutritional sulfur monospores, and sulfur-oxidizing lemon spores combined with a sodium ethylenediaminetriacetate ligand has a synergistic effect, and the similar effects on No. 1 and No. 2 nickel-cobalt-copper sulfide ores prove the stability and universality of the bio-leaching agent.

[0079] Example 7

[0080] Thioclavapacifica pacifica MCCC 1A03188, Thiomicrorhabdus sediminis MCCC 1A14511, Sulfurimonaslithotrophica MCCC 1A14739, Citreicella thiooxidans MCCC1A13021, and Halothiobacillus neapolitanus MCCC 1A18420 were inoculated into a composite culture medium containing nickel-cobalt-copper sulfide ore powder, and cultured for 20 days under pH 7.5, and then filtered and centrifuged to obtain bacterial sludge; wherein the specific formula of the composite culture medium containing nickel-cobalt-copper sulfide ore powder is: (NH 4 ) 2 SO 4 3.0 g / L, MgSO 4 7H 2 O 0.5g / L, K 2 HPO 4 0.5 g / L, KCl 0.1 g / L, Ca(NO 3 ) 2 0.01g / L, NaCl 25g / L, acetic acid 5g / L, yeast extract powder 0.5g / L, No. 1 mineral powder 50g / L;

[0081] The bacterial sludge was then inoculated into a composite culture medium containing reduced sulfur for amplification culture for 10 days, and a bacterial suspension (bacterial concentration was about 4.0×109 cells / mL) was obtained by filtration. The specific formula of the composite culture medium containing reduced sulfur was: (NH 4 )2 SO 4 3.0g / L, MgSO 4 7H 2 O 0.5g / L, K 2 HPO 4 0.5 g / L, KCl 0.1 g / L, Ca(NO 3 ) 2 0.01g / L, NaCl 25g / L, acetic acid 5g / L, yeast extract 0.5g / L, sodium thiosulfate 3g / L and pyrite 5g / L;

[0082] Add 1g of sodium ethylenediaminetriacetate ligand and 1.5g of glycine ligand to 100mL of bacterial suspension, adjust pH to 7.5 to prepare microorganism-ligand leaching agent; then, according to the leaching liquid-solid ratio of 100:5 (No. 1 nickel-cobalt-copper sulfide ore), the ore is leached with the microorganism-ligand leaching agent, and the leaching process is carried out in a constant temperature oscillator at a temperature of 30°C and a speed of 200rpm. The leachate is collected after 50 days of leaching. The leachate is tested by ICP-AES, and the leaching rates of Ni, Co, and Cu are 85.0%, 83.3%, and 45.7%, respectively, and the leaching rate of impurity element Mg is only 6.5%.

[0083] Example 8

[0084] The same microbial suspension as in Example 7 was used to leach the No. 2 nickel-cobalt-copper sulfide ore according to the same leaching process as in Example 7 to obtain a leachate. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 88.8%, 87.9%, and 46.0%, respectively, and the leaching rate of the impurity element Mg was only 6.0%.

[0085] Comparative Example 7

[0086] Take 100 mL of sterile culture medium, add 1 g of sodium ethylenediaminetriacetate ligand and 1.5 g of glycine ligand, adjust the pH to 7.5 to prepare a chemical leaching agent, and leach the ore according to the same leaching process as in Example 7. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 50.5%, 48.1%, and 30.2%, respectively.

[0087] Comparative Example 8

[0088] 100 mL of the same microbial suspension as in Example 7 was taken without adding a ligand, and the ore was leached according to the same leaching process as in Example 7. The leachate was tested by ICP-AES, and the leaching rates of Ni, Co, and Cu were 0.6%, 0.3%, and 0.1%, respectively.

[0089] Combining the results of Example 7, Example 8, Comparative Example 7 and Comparative Example 8, we can see that the leaching effects of Example 7 and Example 8 are similar, and are significantly better than Comparative Example 7 and Comparative Example 8, indicating that the bio-ligand leaching agent composed of Pacific sulfur-expansive Bacillus, sediment sulfur microbacterium, inorganic nutrient sulfur monosporus, sulfur-oxidizing lemon spore bacteria, and Naples salt sulfur microbacterium combined with sodium ethylenediaminetriacetate ligand and glycine ligand has a synergistic effect, and the similar effects on No. 1 and No. 2 nickel-cobalt-copper sulfide ores prove the stability and universality of the bio-leaching agent.

Claims

1. A method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions, characterized in that: The following steps are involved: S1. Inoculating the microorganisms into a composite culture medium containing nickel-cobalt-copper sulfide ore powder for acclimatization and culture, and centrifuging to obtain bacterial sludge; S2. The bacterial sludge obtained in step S1 is inoculated into a composite medium containing reduced sulfur for amplification and culturing, and filtered to obtain a bacterial suspension; S3. Add the ligand to the bacterial suspension obtained in step S2, adjust the pH, and obtain a microorganism-ligand extractant; S4. The nickel-cobalt-copper sulfide ore is mixed with the microorganism-ligand leaching agent obtained in step S3, and biological leaching is performed. After the biological leaching is completed, solid-liquid separation is performed to obtain a leachate containing nickel-cobalt-copper valuable metal ions.

2. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 1, characterized in that: In step S1, the microorganisms include one or more of autotrophic, heterotrophic or facultative sulfur-oxidizing microorganisms that prefer near-neutral pH conditions.

3. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 2, characterized in that: Autotrophic microorganisms include microorganisms of the genera Thiobacillus, Halophilic Thiobacillus, Thiomonas, Rhizobium, Thiobacillus, Thermothiobacillus, and Thiomicrospirillum; Heterotrophic microorganisms include Bacillus, Citrobacter, and Lactobacillum microorganisms; Facultative microorganisms include microorganisms of the genera Thiobacillus and Thiomonas.

4. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 3, characterized in that: The microorganism can oxidize reduced sulfur substances such as thiosulfate, sulfide, elemental sulfur or tetrasulfate under the conditions of pH 4 to 10.5, temperature of -1 to 45°C and salinity of 0 to 100 g / L NaCl.

5. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 1, characterized in that: The matrix of the composite culture medium containing nickel-cobalt-copper sulfide ore powder includes a carbon source, a nitrogen source, an inorganic salt, vitamins, and nickel-cobalt-copper sulfide ore powder; wherein the amount of the carbon source is 10 to 100 mmol / L in terms of carbon content, the amount of the nitrogen source is 10 to 100 mmol / L in terms of nitrogen content, and the amount of the inorganic salt satisfies that the phosphorus, potassium, magnesium, and calcium contents are 0.01 to 20 mmol / L.

6. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 5, characterized in that: The carbon source includes one or more of calcium carbonate, acetic acid, succinic acid, malic acid, lactic acid, pyruvic acid, citric acid, propionic acid, butyric acid, gluconic acid, glycolic acid, glyoxylic acid, ethanol, glycerol, mannitol, sorbitol, glucose, fructose, maltose, sucrose, L-arabinose, D-cellobiose, starch, proline, lysine, alanine, glutamic acid, glutamine, aspartic acid, asparagine, leucine, and arginine; The nitrogen source includes one or more of bean cake powder, corn steep liquor, yeast extract, yeast extract powder, nitrate, urea, and ammonium salt; Inorganic salts include inorganic salts in carbon sources and nitrogen sources, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tricalcium phosphate, potassium chloride, calcium nitrate, magnesium sulfate and sodium chloride; Vitamins include biotin (vitamin H), pyridoxine (vitamin B6), and thiamine (vitamin B1), and the dosage is 10-100 μmol / L; The content of nickel-cobalt-copper sulfide ore powder in the matrix of the composite culture medium containing nickel-cobalt-copper sulfide ore powder is 1-20 g / L; The composite culture medium containing nickel-cobalt-copper sulfide ore powder is prepared by deionized water or artificial seawater. In particular, the artificial seawater is composed of: NaCl 26.726 g / L, MgCl2 2.26 g / L, MgSO4 3.248 g / L, CaCl2 1.153 g / L, NaHCO3 0.198 g / L, KCl 0.721 g / L, NaBr 0.058 g / L, H3BO3 0.058 g / L, Na2SiO3 0.0024 g / L, Na2Si4O9 0.0015 g / L, H3PO4 0.002 g / L, Al2Cl6 0.013 g / L, NH3 0.002 g / L, and LiNO3 0.0013 g / L.

7. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 1, characterized in that: The process conditions of the acclimation culture are: the culture time is 10 to 60 days, the culture temperature is 25 to 35° C., the pH is adjusted to 5 to 9 using 1 mol / L hydrochloric acid and 1 mol / L sodium hydroxide solution, the acclimation is carried out in a shaking bottle, the rotation speed is 160 to 180 rpm, and no aeration is required; The centrifugal speed is 9000-11000 rpm and the time is 18-22 minutes.

8. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 1, characterized in that: In step S2, the matrix of the composite culture medium containing reduced sulfur includes a carbon source, a nitrogen source, an inorganic salt, vitamins, and a reduced sulfur substance, wherein the carbon source, the nitrogen source, the inorganic salt, the vitamins and the configuration are the same as those of the composite culture medium containing nickel-cobalt-copper sulfide ore powder in step S1; The sulfur-reducing substance includes one or more of sodium thiosulfate, pyrite, and elemental sulfur; the content of the sulfur-reducing substance in the composite culture medium containing reduced sulfur is 1 to 20 g / L; The process conditions of the amplification culture are: the culture time is 1 to 10 days, the culture temperature is 25 to 35°C, 1 mol / L hydrochloric acid and 1 mol / L sodium hydroxide solution are used to adjust the pH to 5 to 9, the amplification culture is carried out in a shaking bottle, the rotation speed is 170 rpm, and no aeration is required; The viable count of the bacterial suspension is 10 9 ~10 10 Pieces / mL.

9. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 1, characterized in that: In step S3, the ligand includes one or more of aspartic acid, glycine, citric acid and its salts, nitrilotriacetic acid and its salts, iminodiacetic acid and its salts, ethylenediaminetetraacetic acid and its salts, diethylenetriamine, and diethylenetriaminepentaacetic acid; After the ligand is added, the concentration of the ligand in the solution is 1-50 g / L; after mixing, the pH range is adjusted to 5-9.

10. The method for leaching nickel-cobalt-copper sulfide ore under near-neutral pH conditions according to claim 1, characterized in that: In step S4, the process conditions of the biological leaching are: liquid-to-solid ratio of 10:(0.1-3), leaching time of 10-60 days, leaching temperature of 25-35°C, pH adjusted to 5-9 using 1 mol / L hydrochloric acid and 1 mol / L sodium hydroxide solution, leaching is carried out in a shaking bottle at a rotation speed of 200 rpm, and no aeration is required.