Method for regulating and deacidifying low-grade copper sulphide ore in bioleaching process

Abstract

The invention relates to a method for regulating and deacidifying in a bioleaching process of low-grade copper sulphide ore, aiming at the problem of excessive acid caused by excessive oxidation of pyrite in a dump leaching system, a thiocyanate bactericide is added into the bioleaching system of the low-grade copper sulphide ore, and the thiocyanate bactericide is dissolved in a spray liquid of the bioleaching system, and is added into the spray liquid of the bioleaching system; under the catalytic action of mineral leaching microorganisms, oxidation of ferrous ions is enhanced, so that the oxidation-reduction potential of a solution is increased, oxidation of pyrite is intensified, acid accumulation is excessive, the thiocyanate bactericide can remarkably inhibit the activity of part of sulfur-oxidizing bacteria and even kill part of sulfur-oxidizing bacteria, and therefore the activity of ferrous oxide is reduced; compared with the prior art, the method has the advantages that the sulfur oxidation activity of microorganisms is greatly influenced, but the oxidation influence on iron is relatively small, so that the acid leaching is reduced under the condition that the copper leaching of the copper sulfide ore is not influenced, the copper leaching is not influenced, the acid leaching is reduced, the production cost is reduced, the environmental influence is reduced, and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy, and particularly relates to a method for regulating and reducing acid in a low-grade copper sulfide ore bioleaching process. BACKGROUND

[0002] With the continuous development of global copper resources, the reserves of high-grade copper ore gradually decrease, and the development of low-grade copper sulfide ore becomes an important direction of copper resource utilization. Due to the low copper content in low-grade copper sulfide ore, the traditional physical beneficiation and chemical leaching methods not only have poor economic efficiency, but also cause great pollution to the environment. Bioleaching technology is a method that uses microorganisms (such as Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans) to oxidize sulfides in copper sulfide ore into soluble copper ions. This technology has the advantages of low cost, environmental friendliness, and simple operation, and is particularly suitable for processing low-grade copper sulfide ore. In recent years, with the cross development of microbiology, metallurgy, and environmental engineering, the application of bioleaching technology in low-grade copper sulfide ore processing has made significant progress. In the bioleaching process, microorganisms oxidize sulfur and iron elements in copper sulfide ore to convert sulfides into sulfates and release copper ions. The copper ions in the leaching solution can be recovered through subsequent extraction and electrodeposition processes, thereby realizing efficient utilization of copper resources. Compared with traditional methods, bioleaching technology not only can significantly reduce production costs, but also can reduce the use of chemical reagents and reduce environmental pollution. However, bioleaching technology still faces some challenges in practical application: for example, the activity of microorganisms is greatly affected by factors such as temperature, pH value, and nutrient conditions, the leaching rate is slow, the leaching solution may contain various impurity ions, and especially the content of pyrite in the ore is high, the acid consumption of gangue is low, the oxidation of pyrite produces acid, which exceeds the needs of bioheap leaching, and continuously accumulates in the heap leaching solution system, the accumulation of acid reduces the copper leaching rate of leaching microorganisms, and increases environmental cost and environmental pressure. Therefore, how to solve the problem of excessive acid caused by excessive oxidation of pyrite in the heap leaching system is of great significance for reducing the production cost of copper sulfide ore heap leaching and reducing environmental risk.

[0003] To solve the above problems, successively disclosed: CN110527830A "A method for biological leaching of chalcopyrite", it is to chalcopyrite biological leaching system adding reagent, the reagent includes surfactant and / or isothiazolinone bactericide, the method claims that the operation is simple, the cost is lower, by adding reagent in biological leaching system, can control the oxidation process of microorganism to ferrous, thereby adjust the potential of leaching solution, and effectively solve the problem that chalcopyrite leaching process is hindered by the passivation of surface and further leaching of chalcopyrite, improve the biological leaching rate of chalcopyrite, but the bactericide used in this method focuses on reducing the leaching of acid in ore, only can reduce the subsequent environmental treatment cost;CN117821746A "A method for regulating and extracting copper in biological leaching process of low-grade primary copper ore", it uses leaching bacteria (Leptospirillum sp and Acidiphilium sp. The relative abundance is ≥20% and 10% respectively), can carry out first cycle leaching to low-grade primary copper ore, and after the first cycle leaching reaches the maximum leaching limit, adjust (improve) the leaching temperature, continue to carry out second cycle leaching to low-grade primary copper ore with thermophilic leaching bacteria (Sulfobacillus sp., relative abundance ≥15%), until the leaching endpoint is reached, but it cannot regulate the biological leaching process in stages, the biological leaching efficiency of chalcopyrite mineral phase and the dissolution rate of chalcopyrite mineral phase in the second cycle leaching process are low, the total leaching rate of copper in primary copper ore is not high, and the bactericide used will change the microbial community structure, cannot reduce the leaching of acid in ore, and the subsequent environmental treatment cost is high.

[0004] Therefore, it is of great significance to develop a high-efficiency, environmentally friendly and economical method for regulating and reducing acid in biological leaching process of low-grade copper sulfide ore. SUMMARY

[0005] The present application provides a method for regulating and reducing acid in biological leaching process of low-grade copper sulfide ore, which can not only affect the leaching of copper, but also reduce the leaching of acid, reduce production cost and reduce environmental impact.

[0006] The present application adopts the following technical scheme:

[0007] The application discloses a method for regulating and reducing acid in a low-grade copper sulfide ore bioleaching process.

[0008] Compared with the prior art, the application has the following advantages or beneficial effects:

[0009] Because the thiocyanate bactericide is added in the spraying liquid of the bioleaching system, the bioleaching effect of the low-grade copper sulfide ore can be remarkably improved; meanwhile, the oxidation of ferrous ions is enhanced under the catalysis of the leaching microorganism, so that the oxidation-reduction potential of the solution is increased, the oxidation of pyrite is intensified, and the acid and iron are accumulated in excess, and the activity of part of sulfur-oxidizing bacteria can be remarkably inhibited, which provides technical support for sustainable development of copper resources.

[0010] In the present application, P 80 is a particle size value that 80% of particles can reach, P 80 <40mm indicates that 80% of particles have a particle size less than 40mm, and % is a mass percentage. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a columnar graph of copper and sulfur leaching rates in the leaching system of the inventive example and the comparative example. Figure 2 is a curve graph of changes of copper and sulfur leaching rates with leaching time in the inventive example 1 and the comparative example 1. Figure 3 is a comparison graph of oxidation-reduction potentials of the spraying liquid and the leaching liquid in the inventive example 1 and the comparative example 1. Figure 4 is a curve graph of changes of oxidation-reduction potentials of the leaching liquid with leaching time in the inventive example 1 and the comparative example 1. DETAILED DESCRIPTION

[0011] The application will be further described in detail in combination with specific embodiments.

[0012] Reference Figures 1 to 4The application discloses a method for regulating and reducing acid in a low-grade copper sulfide ore bioleaching process.

[0013] The method can further be

[0014] The thiocyanate bactericide includes any one or a combination of sodium thiocyanate, potassium thiocyanate and ammonium thiocyanate.

[0015] The thiocyanate bactericide is used in an amount of 5-50 mg / L of the spraying liquid.

[0016] The bioleaching system includes a microbial column leaching system.

[0017] The leaching solution in the bioleaching system is extracted, and the obtained raffinate is recycled as the spraying liquid.

[0018] The bioleaching system includes copper sulfide ore, a spraying liquid, a leaching solution and acidophilic microorganisms.

[0019] The spraying liquid is raffinate.

[0020] The sodium thiocyanate is directly added into the spraying liquid.

[0021] The spraying liquid contains 8-20 g / L of sulfuric acid and 10-15 g / L of ferric ions.

[0022] The low-grade copper sulfide ore has a particle size P 80 <40 mm.

[0023] The acidophilic microorganisms include any one or a combination of Leptospirillum, Thiobacillus, Ferrobacillus, Sulfobacillus or Acidimicrobium.

[0024] The acidophilic microorganisms include any one or a combination of iron-oxidizing bacteria, sulfur-oxidizing bacteria and iron-sulfur-oxidizing bacteria.

[0025] The acidophilic microorganisms are from any one or a combination of ore, tailings, a spraying liquid and acid mine drainage.

[0026] The acidophilic microorganisms are inoculated or naturally grown in the ore of the bioleaching system or in the spraying liquid of the bioleaching system.

[0027] The following are typical but non-limiting examples of the present application:

[0028] Example 1

[0029] The main component of the low-grade copper sulfide ore is digenite, and the elements in the ore are: copper 0.16%, Fe 2.81%, and S 3.73%. The bio-column leaching method is used for leaching the copper ore, and the leaching method is as follows:

[0030] (1) The ore is crushed to a particle size of less than 40 mm, the acid concentration in the spraying liquid is 10 g / L, the iron concentration is 12 g / L, and the main strains in the spraying liquid include Thiobacillus ferrooxidans, Acidithiobacillus ferrooxidans, and Leptospirillum ferriphilum;

[0031] (2) A reagent is added to the spraying liquid, the reagent is sodium thiocyanate, and the usage amount is 20 mg / L of the spraying liquid, and the bio-column leaching method is used for leaching;

[0032] (3) The spraying intensity is 15 L / m 2 ·h, and the spraying and resting system is as shown in Table 1:

[0033] Table 1 Spraying and resting system

[0034] Spray phase Heap leach cycle Spray rest pattern First phase First month Continuous spray Second phase Second month Spray 1 day, rest 1 day Third phase 3rd to 4th month Spray 1 day, rest 3 days Fourth phase 5th to 7th month Spray 1 day, rest 5 days

[0035] (4) When the Cu concentration of the leaching liquid reaches 2 g / L, extraction treatment is performed, the raffinate is returned as the spraying liquid, and the reagent is supplemented, and the spraying is continued in circulation.

[0036] Example 2

[0037] The method is the same as that in Example 1, and the object of treatment is the old ore after spraying for 220 days, and the elements in the ore are: copper 0.088%, Fe 4.17%, and S 3.85%. The spraying time is 2 months, and the spraying and resting system is spraying for 1 day and resting for 5 days.

[0038] Example 3

[0039] The method is the same as that in Example 2, and the object of treatment is the old ore after spraying for 300 days, and the elements in the ore are: copper 0.072%, Fe 4.14%, and S 3.01%.

[0040] Comparative Example 1

[0041] The method is the same as that in Example 1, except that no reagent is added in step (2).

[0042] Comparative Example 2

[0043] The method is according to Example 2, except that step (2) does not add the reagent.

[0044] Comparative Example 3

[0045] The method is according to Example 3, except that step (2) does not add the reagent.

[0046] From Figure 1 It can be seen that after spraying for 212 days, the copper leaching rates of the examples are all higher than those of the comparative examples, among which the copper leaching rate of Example 1 is about 12% higher than that of Comparative Example 1, the copper leaching rate of Example 2 is about 10% higher than that of Comparative Example 2, and the copper leaching rate of Example 3 is about 8% higher than that of Comparative Example 3; at the same time, the sulfur leaching rate of Example 1 is about 2% lower than that of Comparative Example 1, the sulfur leaching rate of Example 2 is about 1% lower than that of Comparative Example 2, and the sulfur leaching rate of Example 3 is about 1% lower than that of Comparative Example 3.

[0047] From Figure 2 It can be seen that after spraying for 212 days, the copper leaching rate of Comparative Example 1 reaches more than 66%, and the copper leaching rate of Example 1 reaches more than 78%, and the trends of the two are consistent, but the copper leaching rate of Example 1 is always higher than that of Comparative Example 1; the sulfur leaching rate of Comparative Example 1 is about 3.3%, and the sulfur leaching rate of Example 1 is about 1.3%, and the trends of the two are consistent, but the sulfur leaching rate of Comparative Example 1 is always higher than that of Example 1.

[0048] From Figure 3 It can be seen that from the 16th day of spraying, the redox potential of the leaching solution of Comparative Example 1 gradually increases, and is higher than the redox potential of the spraying solution on the 28th day of spraying, indicating that from the 16th day of spraying, the process of oxidizing ferrous iron in the ore to Fe 3+ starts to strengthen, and from the 28th day of spraying, the abundance of bacteria in the leaching solution is dominated by iron-oxidizing bacteria, and bacterial oxidation of ferrous iron plays a dominant role. For Example 1, the redox potential of the leaching solution is always lower than that of the spraying solution, indicating that the concentration of Fe 3+ in the leaching solution is lower than that in the spraying solution.

[0049] From Figure 4 It can be seen that the redox potentials of Example 1 and Comparative Example 1 are not much different in the early stage of spraying, and the difference between the redox potentials of the leaching solutions of the two becomes larger and larger, the redox potential of the leaching solution of Comparative Example 1 becomes higher and higher, and approaches 710 mV, while the change range of the leaching solution of Example 1 is smaller, and is between 500-610 mV.

[0050] As can be seen from Table 2 below, the relative abundance of the microbial community composition in the leaching solution of Example 1 from large to small is Leptospirillum (47.48%), Ralstonia (12.47%), Pseudomonas (6.43%), Streptomyces (3.27%), Acinetobacter (3.11%) and Cloacibacterium (3.06%); the relative abundance of the microbial community composition in the leaching solution of Comparative Example 1 from large to small is Leptospirillum (68.32%) and Acidithiobacillus (29.99%). The microbial diversity in the leaching solution of Example 1 is higher than that in the leaching solution of Comparative Example 1. In the leaching solution of Comparative Example 1, the microorganisms are almost Leptospirillum and Acidithiobacillus, but the microorganisms in the leaching solution of Example 1 do not contain Acidithiobacillus, and the relative abundance of Leptospirillum is lower than that in the leaching solution of Comparative Example 1.

[0051] Table 2 Comparison of relative abundance of microbial community composition in leaching solutions of Example 1 and Comparative Example 1

[0052]

[0053]

[0054] As described above, the present application can be better implemented. The above examples are only the best embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and other changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. A method for regulating and reducing acid in a low-grade copper sulfide ore bioleaching process, aiming at the problem of acid excess caused by excessive oxidation of pyrite in a heap leaching system, characterized in that The thio cyanate bactericide is added to a low-grade copper sulfide ore bioleaching system, and the adding method is dissolving in the spray liquor of the bioleaching system. Under the catalysis of the leaching microorganism, the oxidation of ferrous ions is enhanced, the redox potential of the solution is increased, the oxidation of pyrite is intensified, the acid accumulation is excessive, and the thio cyanate bactericide can significantly inhibit the activity of part of sulfur-oxidizing bacteria and even kill part of sulfur-oxidizing bacteria, thereby reducing the activity of the sulfur-oxidizing bacteria in oxidizing ferrous ions. The thio cyanate bactericide has a relatively large influence on the sulfur-oxidizing activity of the microorganism, but has a relatively small influence on the oxidation of iron, so that the leaching of acid is reduced without affecting the leaching of copper from the copper sulfide ore.

2. The method of claim 1 wherein The thio cyanate bactericide includes any one or a combination of sodium thiocyanate, potassium thiocyanate, and ammonium thiocyanate.

3. The method of claim 1 or 2, wherein The amount of the thio cyanate bactericide is 5-50 mg / L of the spray liquor.

4. The method of claim 1 wherein The bioleaching system includes a microbial column leaching system.

5. The method of claim 1 wherein The bioleaching system includes copper sulfide ore, spray liquor, leaching solution, and acidophilic microorganism.

6. The method of claim 1 or 4 or 5, wherein The leaching solution in the bioleaching system is extracted to obtain a raffinate, and the raffinate is recycled as the spray liquor.

7. The method of claim 1 wherein The spray liquor is the raffinate.

8. The method of claim 1 wherein The sodium thiocyanate is directly added to the spray liquor.

9. The method of claim 1 or 8, wherein The concentration of sulfuric acid in the spray liquor is 8-20 g / L, and the concentration of ferric ions is 10-15 g / L.

10. The method of claim 1 wherein The particle size P of the low-grade copper sulfide ore 80 < 40 mm.

11. The method of claim 5 wherein The acidophilic microorganism includes any one or a combination of Leptospirillum, Thiobacillus, Ferrobacillus, Sulfobacillus, or Acidimicrobium.

12. The method of claim 5 wherein The acidophilic microorganism includes any one or a combination of iron-oxidizing bacteria, sulfur-oxidizing bacteria, or iron-sulfur-oxidizing bacteria.

13. The method of claim 5 wherein The acidophilic microorganism is from any one or a combination of ore, tailings, spray liquor, or acid mine drainage.

14. The method of claim 5 or 11 or 12 or 13 wherein The acidophilic microorganism is inoculated or naturally grown in the ore of the bioleaching system or the spray liquor of the bioleaching system.

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