A method for bioleaching chalcopyrite

Abstract

The present invention provides a method for bioleaching chalcopyrite, comprising the following steps: (1) crushing the chalcopyrite into an ore pile, and burying a vertical pipe in the ore pile; (2) spraying the ore pile with sulfuric acid, and then inoculating leaching microorganisms to realize bioleaching operation; (3) during the operation of the bioleaching operation, regularly spraying a spray liquid on the top of the ore pile, and adding hydrogen peroxide to the spray liquid according to the change in copper ion concentration. The method provided by the present invention utilizes a Fenton-like reaction to cooperate with biooxidation to eliminate the passivation layer on the surface of the chalcopyrite and hinder the regeneration of the passivation layer, thereby improving the leaching efficiency of the chalcopyrite, achieving efficient bioleaching of the chalcopyrite, and having low cost, simple operation, and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a chalcopyrite bioleaching method, and in particular to a chalcopyrite bioleaching method with high leaching efficiency. Background Art

[0002] Bioheap leaching can directly utilize low-grade copper ores, avoiding the energy-intensive and highly polluting grinding, beneficiation, and smelting steps of the mining and metallurgy process. This not only reduces production costs and simplifies the process, but also eliminates harmful flue gas emissions, offering significant economic and environmental advantages. To date, nearly a quarter of the world's copper production is produced through bioheap leaching. However, bioheap leaching is currently primarily used to treat low-grade ores containing secondary copper sulfides, such as chalcocite (Cu2S). Large-scale industrial application of ores containing primary copper sulfides, such as chalcopyrite (CuFeS2), remains difficult due to the slow bioleaching rate of copper. Chalcopyrite is an economically important primary copper sulfide, accounting for approximately 70% of the world's total copper resources. Bioleaching of low-grade chalcopyrite would yield economic benefits far exceeding those achieved by utilizing only secondary copper sulfides.

[0003] Numerous studies have confirmed that the reason for the low bioleaching rate of chalcopyrite is that after a certain stage of bioleaching, the passivation layer on the chalcopyrite surface hinders direct contact between the solution and the chalcopyrite surface, hindering charge transfer. This phenomenon is called surface passivation, which can cause the leaching rate to drop sharply or even stop. Currently, there are several methods to remove or reduce the surface passivation of chalcopyrite, including the following:

[0004] Adding Cl to the bioleaching system - , using Cl - The high permeability of Cl promotes the dissolution of chalcopyrite and inhibits the formation of passivation film. - Excessively high concentrations will affect microbial growth, inhibit the sulfur oxidation ability of microorganisms, and affect subsequent extraction and electrolysis processes, causing equipment corrosion and deterioration in the quality of metallic copper products.

[0005] Increasing the temperature or using bioleaching and ozone oxidation in staged reactions can remove the passivation film formed on chalcopyrite during bioleaching, achieving efficient chalcopyrite leaching. However, increasing the temperature or performing staged leaching are technically difficult to implement in large-scale heap leaching processes, and there are no reports of these methods being applied industrially.

[0006] Adding Ag + As a catalyst, it can significantly increase the bioleaching rate of chalcopyrite. + The catalytic effect is good and the impact on microorganisms is small. When bioleaching is carried out in a stirred tank, Ag +The catalytic effect of chlorpyrifos can increase the leaching rate of chalcopyrite to nearly 90%, and in simulated bio-heap leaching, it can also increase the leaching rate of copper by more than 100%. However, silver is expensive, and in actual bio-heap leaching, it will form iron silver alum precipitation and be lost, resulting in increased production costs.

[0007] Therefore, how to provide a method that can destroy the passivation film on the surface of chalcopyrite and improve the biological oxidation efficiency of chalcopyrite has become an urgent problem to be solved. Summary of the Invention

[0008] In response to the shortcomings of the prior art, the present invention aims to provide a method for bioleaching chalcopyrite, particularly a method for bioleaching chalcopyrite with high leaching efficiency. The method utilizes a Fenton-like reaction in conjunction with biooxidation to eliminate the passivation layer on the chalcopyrite surface and hinder its regeneration, thereby improving the leaching efficiency of the chalcopyrite. This method achieves efficient bioleaching of the chalcopyrite with low cost, ease of operation, and environmental friendliness.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for bioleaching chalcopyrite, which comprises the following steps:

[0011] (1) Crushing the chalcopyrite into an ore pile and burying a vertical pipe in the ore pile;

[0012] (2) Spraying the ore pile with sulfuric acid and then inoculating the leaching microorganisms to achieve bioleaching operation;

[0013] (3) During the operation of the bioleaching heap, spray liquid is sprayed regularly on the top of the ore pile, and hydrogen peroxide is added to the spray liquid according to the changes in the copper ion concentration.

[0014] The method adds H2O2 without affecting the normal growth of leaching microorganisms, and utilizes a Fenton-like reaction to oxidize monovalent copper and divalent iron on the surface of the chalcopyrite. Copper is leached first, and sulfur forms a loose elemental sulfur covering layer, which reduces the obstruction to the bioleaching process. The strong oxidizing property of the Fenton-like reaction itself is also conducive to the oxidation and dissolution of sulfur, destroying the already formed passive covering layer, thereby achieving the purpose of hindering the regeneration of the passive layer and eliminating the passive layer on the surface of the chalcopyrite. At the same time, it can cooperate with the biological oxidation effect to improve the leaching efficiency of the chalcopyrite, providing an economically feasible, easy-to-operate, energy-saving and environmentally friendly method for enhanced bioleaching of chalcopyrite.

[0015] Preferably, the upper portion of the vertical pipe in step (1) is not lower than the top of the ore pile, and the lower portion is at least 30 cm higher than the bottom of the ore pile.

[0016] Preferably, the density of the vertical pipes in the ore pile in step (1) is 8-10 pipes / m 2, for example 8 pieces / m 2 , 9 pieces / m 2 or 10 pieces / m 2 .

[0017] Preferably, the concentration of sulfuric acid in step (2) is 0.04-0.08 mol / L, such as 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L or 0.08 mol / L, but is not limited to the above-listed values. Other values ​​not listed within the above numerical range are also applicable.

[0018] Preferably, the spraying amount of sulfuric acid in step (2) is 1-2 L / m 3 , for example 1L / m 3 , 1.1L / m 3 , 1.2L / m 3 , 1.3L / m 3 , 1.4L / m 3 , 1.5L / m 3 , 1.6L / m 3 , 1.7L / m 3 , 1.8L / m 3 , 1.9L / m 3 or 2L / m 3 The above values ​​are not limited to the above values. Other values ​​not listed in the above value range are also applicable.

[0019] Preferably, the leaching microorganisms in step (2) include Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans;

[0020] Preferably, after the inoculation of the leaching microorganisms in step (2), the initial density of the leaching microorganisms is 1×10 6 -1×10 8 pieces / mL.

[0021] Preferably, the regular spraying of the spray liquid in step (3) is specifically performed once every 7-10 days, and the total amount of each spray is 800-1200 mL, for example, 800 mL, 900 mL, 1000 mL, 1100 mL or 1200 mL, etc., but is not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0022] Preferably, the step (3) of adding hydrogen peroxide to the spray liquid according to the change in copper ion concentration is specifically as follows:

[0023] Detect the copper ion concentration in the heap leachate. When the copper ion concentration rises slowly and the microbial density is greater than 1×10 6 When the concentration of HCl / mL was 0.1, hydrogen peroxide was added to the spray solution.

[0024] Preferably, the mass fraction of hydrogen peroxide added to the spray liquid in step (3) is 0-0.5%, but excluding 0.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a chalcopyrite bioleaching method. H2O2 is added without affecting the normal growth of leaching microorganisms, and monovalent copper and divalent iron on the surface of the chalcopyrite are oxidized by a Fenton-like reaction. Copper is leached first, and sulfur forms a loose elemental sulfur covering layer, which reduces the obstruction to the bioleaching process. The strong oxidizing property of the Fenton-like reaction itself is also conducive to the oxidation and dissolution of sulfur, destroying the formed passivation covering layer, thereby achieving the purpose of hindering the regeneration of the passivation layer and eliminating the passivation layer on the chalcopyrite surface. At the same time, the method can cooperate with the biological oxidation effect to improve the leaching efficiency of the chalcopyrite, thereby providing an economically feasible, easy-to-operate, energy-saving and environmentally friendly method for enhanced bioleaching of chalcopyrite. DETAILED DESCRIPTION

[0027] In order to further illustrate the technical means and effects adopted by the present invention, the technical solutions of the present invention are further described below in conjunction with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

[0028] In the following example, chalcopyrite comes from a mine in Diqing, Yunnan.

[0029] Example 1

[0030] This embodiment provides a method for bioleaching chalcopyrite, and the specific steps are as follows:

[0031] (1) Chalcopyrite bio-heap leaching. Crushed ore into a heap, and a certain number of vertical pipes were buried so that part of the spray liquid could directly reach the bottom of the ore heap. The vertical pipe density was 9 pipes / m 2 The inner diameter of the vertical pipe is 2 cm, and the side of the pipe is opened with 4 holes opened every 10 cm around the pipe. The hole diameter is 0.5 cm. The upper part of the vertical pipe is not lower than the top of the ore pile, and the lower part of the vertical pipe is 30 cm away from the bottom.

[0032] (2) After spraying acidification with 0.046 mol / L dilute sulfuric acid (1.5 L / m 3 ), inoculated with Acidithiobacillus ferrooxidans (At.f) and Thiobacillus thiooxidans (Tt) (inoculation ratio 1:1), and the initial density of the leaching microorganisms was 1×10 7 / mL until the microorganisms are colonized in the heap and the bioleaching heap operates stably;

[0033] (3) Spray with 0.5% H2O2 at a flow rate of 100 mL / min for 10 minutes every 10 days.

[0034] (4) Continuously monitor the microbial density and copper ion concentration in the ore pile. When the microbial density in the system is higher than 1×10 6 / mL, and the copper ion concentration growth rate slowed down, 0.5% H2O2 was sprayed at a flow rate of 100mL / min for 10min; when the microbial density in the system was lower than 1×10 6 When the concentration of hydrogen peroxide reaches 100 μg / mL, stop adding hydrogen peroxide to the spray solution.

[0035] Example 2

[0036] This embodiment provides a method for bioleaching chalcopyrite, and the specific steps are as follows:

[0037] (1) Chalcopyrite bio-heap leaching. Crushed ore into a heap, and a certain number of vertical pipes were buried so that part of the spray liquid could directly reach the bottom of the ore heap. The vertical pipe density was 8 pipes / m 2 The inner diameter of the vertical pipe is 2 cm, and the side of the pipe is opened with 4 holes opened every 10 cm around the pipe. The hole diameter is 0.5 cm. The upper part of the vertical pipe is not lower than the top of the ore pile, and the lower part of the vertical pipe is 30 cm away from the bottom.

[0038] (2) After spraying acidification with 0.04 mol / L dilute sulfuric acid (1 L / m 3 ), inoculated with Acidithiobacillus ferrooxidans (At.f) and Thiobacillus thiooxidans (Tt) (inoculation ratio 1:1), and the initial density of the leaching microorganisms was 1×10 6 / mL until the microorganisms are colonized in the heap and the bioleaching heap operates stably;

[0039] (3) Spray with 0.5% H2O2 at a flow rate of 80 mL / min for 10 min every 7 days.

[0040] (4) Continuously monitor the microbial density and copper ion concentration in the ore pile. When the microbial density in the system is higher than 1×10 6 / mL, and the copper ion concentration growth rate slowed down, 0.5% H2O2 was sprayed at a flow rate of 80mL / min for 10min; when the microbial density in the system was lower than 1×10 6 When the concentration of hydrogen peroxide reaches 100 μg / mL, stop adding hydrogen peroxide to the spray solution.

[0041] Example 3

[0042] (1) Chalcopyrite bio-heap leaching. Crushed ore into a heap, and a certain number of vertical pipes were buried so that part of the spray liquid could directly reach the bottom of the ore heap. The vertical pipe density was 10 pipes / m 2 The inner diameter of the vertical pipe is 2 cm, and the side of the pipe is opened with 4 holes opened every 10 cm around the pipe. The hole diameter is 0.5 cm. The upper part of the vertical pipe is not lower than the top of the ore pile, and the lower part of the vertical pipe is 30 cm away from the bottom.

[0043] (2) After spraying acidification with 0.08 mol / L dilute sulfuric acid (2 L / m 3 ), inoculated with Acidithiobacillus ferrooxidans (At.f) and Thiobacillus thiooxidans (Tt) (inoculation ratio 1:1), and the initial density of the leaching microorganisms was 1×10 8 / mL until the microorganisms are colonized in the heap and the bioleaching heap operates stably;

[0044] (3) Spray with 0.5% H2O2 at a flow rate of 120 mL / min for 10 min every 8 days.

[0045] (4) Continuously monitor the microbial density and copper ion concentration in the ore pile. When the microbial density in the system is higher than 1×10 6 / mL, and the copper ion concentration growth rate slowed down, 0.5% H2O2 was sprayed at a flow rate of 120mL / min for 10min; when the microbial density in the system was lower than 1×10 6 When the concentration of hydrogen peroxide reaches 100 μg / mL, stop adding hydrogen peroxide to the spray solution.

[0046] Example 4

[0047] This embodiment provides a method for bioleaching chalcopyrite. The specific steps are similar to those in Example 1, with the only difference being that 1% H2O2 is added in steps (3) and (4).

[0048] Example 5

[0049] This embodiment provides a method for bioleaching chalcopyrite. The specific steps are similar to those in Example 1, with the only difference being that 1.5% H2O2 is added in steps (3) and (4).

[0050] Example 6

[0051] This embodiment provides a method for bioleaching chalcopyrite. The specific steps are similar to those in Example 1, with the only difference being that 2% H2O2 is added in steps (3) and (4).

[0052] Example 7

[0053] This embodiment provides a method for bioleaching chalcopyrite. The specific steps are similar to those in Example 1, with the only difference being that in step (3), spraying is performed once every 20 days.

[0054] Example 8

[0055] This embodiment provides a method for bioleaching chalcopyrite. The specific steps are similar to those in Example 1, with the only difference being that in step (3), spraying is performed once every 30 days.

[0056] Comparative Example 1

[0057] This comparative example provides a method for bioleaching chalcopyrite. The specific steps are similar to those in Example 1, with the only difference being that H2O2 is not added in steps (3) and (4).

[0058] Effect test:

[0059] The chalcopyrite leaching efficiency in Examples 1-8 and Comparative Example 1 was calculated using the following formula:

[0060] Leaching rate = Cu in leachate 2+ Concentration / (total mass of leached ore × copper mass percentage);

[0061] Here are the results:

[0062]

[0063]

[0064] From the above data, it can be found that the method of the present invention for enhancing chalcopyrite bioleaching by utilizing a Fenton-like reaction can achieve efficient leaching of chalcopyrite, is economically feasible, simple to operate, and has prospects for industrial application. Comparison of Examples 1-6 shows that the present invention achieves an effective balance between the destruction of the passivation coating and the effect on microorganisms by controlling the amount of hydrogen peroxide added and the spraying cycle, thereby further improving the chalcopyrite leaching efficiency. Comparison of Example 1 and Comparative Example 1 shows that the present invention effectively improves the chalcopyrite leaching efficiency by utilizing a Fenton-like reaction in conjunction with biological oxidation.

[0065] The applicant states that while the present invention illustrates the chalcopyrite bioleaching method through the aforementioned embodiments, the present invention is not limited to these embodiments, nor does it necessarily rely on these embodiments for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials of the product, addition of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

[0066] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0067] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for bioleaching chalcopyrite, characterized in that: The method comprises the following steps: (1) Crushing the chalcopyrite into a pile and burying a vertical pipe in the pile; (2) Using sulfuric acid to spray the ore pile, and then inoculating the leaching microorganisms to achieve biological leaching operation; (3) During the operation of the bioleaching pile, a spray liquid is regularly sprayed on the top of the ore pile, and the spray liquid is a 0.5% hydrogen peroxide solution; (4) Continuously monitor the microbial density and copper ion concentration in the ore pile. When the microbial density in the system is higher than 1×10 6 / mL, and the copper ion concentration growth rate slowed down, 0.5% H2O2 solution was used for spraying; when the microbial density in the system was lower than 1×10 6 When the concentration of hydrogen peroxide reaches 100 μg / mL, stop adding hydrogen peroxide to the spray solution.

2. The method according to claim 1, characterized in that The upper portion of the vertical pipe in step (1) is not lower than the top of the ore pile, and the lower portion is at least 30 cm higher than the bottom of the ore pile.

3. The method according to claim 1, characterized in that The density of the vertical pipes in the ore pile in step (1) is 8-10 pipes / m 2 .

4. The method according to claim 1, characterized in that Step (1) The vertical pipe is provided with a hole on its side.

5. The method according to claim 1, characterized in that The concentration of sulfuric acid in step (2) is 0.04-0.08 mol / L.

6. The method according to claim 1, characterized in that The spraying rate of sulfuric acid in step (2) is 1-2 L / m 3 .

7. The method according to claim 1, characterized in that The leaching microorganisms in step (2) include Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.

8. The method according to claim 1, characterized in that After the inoculation of leaching microorganisms in step (2), the initial density of the leaching microorganisms is 1×10 6 -1×10 8 pieces / mL.

9. The method according to claim 1, characterized in that The regular spraying of the spray liquid in step (3) is specifically performed once every 7-10 days, with a total amount of 800-1200 mL each time.

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