Potential regulation biological heap leaching process for low-grade copper sulfide ore

Abstract

The application provides a low-grade copper sulfide ore potential regulation bioheap leaching process, which comprises the following steps: copper phase composition analysis is performed on the ore of the low-grade copper sulfide ore, and the suitable range of the oxidation-reduction potential in the bioheap leaching process is determined according to the analysis result. Then, the ore is crushed to a particle size of 1000 mm, sulfuric acid is added and uniformly mixed, and stacking is performed; a culture medium is prepared, leaching bacteria composed of iron-oxidizing bacteria and sulfur-oxidizing bacteria are cultured, and inoculation is performed in the heap; by controlling the proportion of the iron-oxidizing bacteria and the sulfur-oxidizing bacteria in the leaching bacteria group, the aeration amount and the pH value in the heap, and the iron element concentration of the leaching solution, the oxidation-reduction potential of the heap leaching process is regulated to the suitable range of the oxidation-reduction potential, until the heap leaching is completed. According to the differences in the copper phase composition in different ores, the oxidation-reduction potential of the heap leaching process is adapted, so that the copper leaching rate and the copper leaching rate are improved, and the resource utilization of the low-grade copper sulfide ore is realized. Moreover, the process is simple in operation, low in cost, green and environment-friendly, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of biohydrometallurgical technology, and in particular to a potential-controlled bioheap leaching process for low-grade copper sulfide ore. Background Technology

[0002] Copper is a crucial strategic mineral resource in my country. Much of my country's copper resources are low-grade copper sulfide ores (Cu≤0.40%) that are difficult to process and have poor economic returns. Biohydrometallurgical technology offers advantages such as a short process flow, being environmentally friendly (no waste emissions), low cost, and wide applicability, and is widely used in the processing of low-grade copper sulfide ores. Redox potential is the most important process parameter affecting the bioleaching rate and yield of copper sulfide ores. Different copper sulfide minerals have different suitable leaching potentials. For example, secondary copper sulfide ores such as chalcocite and covellite have a suitable redox potential of 460–520 mV vs. Ag / AgCl, while primary copper sulfide ores such as chalcopyrite have a suitable redox potential of 360–460 mV vs. Ag / AgCl. Adjusting the redox potential to the suitable range for dissolving copper sulfide minerals in the bioleaching process can significantly improve the copper leaching rate and yield. However, due to the lack of effective control measures in existing bio-heap leaching processes, the spontaneous growth of leaching microorganisms during conventional heap leaching leads to untimely, inaccurate, or even uncontrollable potential control responses in the leaching system. This results in numerous problems in current industrial bio-heap leaching practices for copper sulfide ores, including unreasonable leaching parameters, slow copper leaching rates, and low leaching rates. This limits the economic exploitation and utilization of low-grade copper sulfide ores, hindering the effective development of a large amount of such copper resources in my country. Therefore, exploring a potential-controlled bio-heap leaching method for low-grade copper sulfide ores has been a major focus of attention. Summary of the Invention

[0003] To address the aforementioned problems in existing technologies, this invention provides a potential-controlled bio-heap leaching process for low-grade copper sulfide ore. The process involves analyzing the copper phase composition of the low-grade copper sulfide ore and determining the appropriate redox potential range during the bio-heap leaching process based on the analysis results. Bacteria are then cultured in a prepared culture medium and inoculated into the constructed ore heap. By controlling the ratio of iron-oxidizing bacteria to sulfur-oxidizing bacteria in the leaching bacterial community, the aeration rate within the heap, the pH value within the heap, and the iron concentration in the leachate, the redox potential during the heap leaching process is adjusted to the appropriate range. This effectively improves the copper leaching rate and extraction yield of the copper sulfide ore, enabling the economical mining and utilization of low-grade copper sulfide ore.

[0004] The specific details of the invention are as follows:

[0005] In a first aspect, the present invention provides a potential-controlled bio-heap leaching process for low-grade copper sulfide ore, the process comprising the following steps:

[0006] S1. The copper phase composition of the low-grade copper sulfide ore is analyzed, and the appropriate range of redox potential is determined based on the analysis results. Then, the ore is crushed to a particle size of less than 1000 mm, sulfuric acid is added and mixed evenly, and then piled up.

[0007] S2. Prepare a culture medium to cultivate leaching bacteria composed of iron-oxidizing bacteria and sulfur-oxidizing bacteria, and inoculate the pile.

[0008] S3. By controlling the ratio of iron-oxidizing bacteria to sulfur-oxidizing bacteria in the leaching bacterial community, the amount of aeration in the pile, the pH value in the pile, and the iron concentration in the leachate, the redox potential during the heap leaching process is adjusted to the appropriate range until the heap leaching is completed.

[0009] Optionally, in step S1, the suitable range of the redox potential is determined by the copper phase composition of the ore; wherein, when the proportion of primary copper sulfide phase in the ore is greater than or equal to 70%, the suitable range of the redox potential is 360-460 mV vs. Ag / AgCl.

[0010] When the proportion of secondary copper sulfide phase in the ore is greater than or equal to 70%, the suitable range of the redox potential is 460-520 mV vs. Ag / AgCl.

[0011] When the proportion of secondary copper sulfide or primary copper sulfide phase in the ore is less than 70%, the suitable range of redox potential in the first stage of the heap leaching process is 460-520 mV vs. Ag / AgCl, and the suitable range of redox potential in the second stage of the heap leaching process is 360-460 mV vs. Ag / AgCl.

[0012] The first stage of the heap leaching process refers to the time period from the start of heap leaching until the amount of copper leached from the ore reaches 80% of the copper content in the secondary copper sulfide of the ore; the second stage of the heap leaching process refers to the time period from when the amount of copper leached from the ore reaches 80% of the copper content in the secondary copper sulfide of the ore until the end of heap leaching.

[0013] Optionally, in step S1, during the stacking process, temperature probes, oxygen partial pressure probes, pH probes, redox potential probes, and gas filling pipes are pre-embedded in the stack.

[0014] The low-grade copper sulfide ore has a copper grade of ≥0.10%;

[0015] The copper sulfide ore is at least one of chalcocite, covellite, bornite, chalcopyrite, chalcopyrite, tetrahedrite, arsenopyrite, and thioarsenic copper ore.

[0016] The copper phase composition includes copper in copper oxide, copper in secondary copper sulfide, copper in primary copper sulfide, and copper in silicates;

[0017] The amount of sulfuric acid used accounts for 1% to 100% of the total sulfuric acid consumption in the heap leaching process.

[0018] Optionally, in step S2, the iron-oxidizing bacteria is at least one of Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Leptospirillum ferriphilum;

[0019] The sulfur-oxidizing bacteria are at least one of Acidithiobacillus thiooxidans, Acidithiobacillus caldus, and Sulfobacillus.sp;

[0020] The main energy source of the culture medium is ferrous sulfate, sulfur powder, and mineral powder of sulfide minerals.

[0021] The sulfide mineral is at least one of pyrite, marcasite, pyrrhotite, arsenopyrite, chalcocite, covellite, chalcopyrite, chalcopyrite, tetrahedrite, arsenopyrite, and thioarsinite.

[0022] The ferrous sulfate is at least one of ferrous sulfate, ferrous sulfate monohydrate, and ferrous sulfate heptahydrate.

[0023] Optionally, in step S3, increasing the redox potential of the heap leaching process is accomplished by at least one of the following methods:

[0024] S31. Increase the pile aeration rate to 0.001 m³ per ton of ore. 3 / h~0.08m 3 Between / h;

[0025] S32. Reduce the pH inside the pile to between 1.00 and 1.50;

[0026] S33. Reduce the iron concentration in the leachate to between 0 and 3 g / L;

[0027] S34. Increase the proportion of iron-oxidizing bacteria in the inoculation solution to over 80%;

[0028] S35. Reduce the proportion of sulfur-oxidizing bacteria in the inoculation solution to below 10%.

[0029] Optionally, in step S34, the method of increasing the proportion of iron-oxidizing bacteria in the inoculation solution is at least one of the following:

[0030] 1) Increase the ferrous ion content in the culture medium to above 3 g / L;

[0031] 2) Reduce the total content of sulfur powder and sulfide mineral powder in the culture medium to 0% to 0.1%;

[0032] 3) Increase the oxygen content of the bacterial culture solution to above 3 mg / L during the bacterial culture process;

[0033] 4) Control the pH range of the bacterial culture solution to 1.0 to 1.50 during the bacterial culture process.

[0034] Optionally, in step S35, the method of reducing the proportion of sulfur-oxidizing bacteria in the inoculation solution is at least one of the following:

[0035] 1) Increase the ferrous ion content in the culture medium to above 3 g / L;

[0036] 2) Reduce the total content of sulfur powder and sulfide mineral powder in the culture medium to below 0.1%;

[0037] 3) Control the pH range of the bacterial culture solution to 1.00 to 1.50 during the bacterial culture process.

[0038] Optionally, in step S3, the reduction of the redox potential during the heap leaching process is accomplished through at least one of the following methods:

[0039] a. Reduce the internal aeration rate to 0.02 m³ / ton of ore. 3 / h or less;

[0040] b. Increase the pH inside the pile to between 1.50 and 2.00;

[0041] c. Increase the iron concentration in the leachate to between 3 and 8 g / L;

[0042] d. Reduce the proportion of iron-oxidizing bacteria in the inoculum to below 10%;

[0043] e. Increase the proportion of sulfur-oxidizing bacteria in the inoculation solution to over 80%.

[0044] Optionally, in step d, the method of reducing the proportion of iron-oxidizing bacteria in the inoculation solution is at least one of the following:

[0045] 1) Reduce the ferrous ion content in the culture medium to below 3 g / L;

[0046] 2) Increase the total content of sulfur powder and sulfide mineral powder in the culture medium to 0.1% to 0.5%;

[0047] 3) Reduce the oxygen content of the bacterial culture solution to below 3 mg / L (including 3 mg / L) during the bacterial culture process;

[0048] 4) Control the pH range of the bacterial culture solution to 1.50–2.00 during the bacterial culture process.

[0049] Optionally, in step e, the method of increasing the proportion of sulfur-oxidizing bacteria in the inoculation solution is at least one of the following:

[0050] 1) Reduce the ferrous ion content in the culture medium to below 3 g / L;

[0051] 2) Increase the total content of sulfur powder and sulfide mineral powder in the culture medium to 0.1% to 0.5%;

[0052] 3) Control the pH range of the bacterial culture solution to 1.50–2.00 during the bacterial culture process.

[0053] Compared with the prior art, the present invention has the following advantages:

[0054] This invention provides a potential-controlled bio-heap leaching process for low-grade copper sulfide ore. The process involves analyzing the copper phase composition of the ore and determining the appropriate redox potential range during the bio-heap leaching process. Bacteria are then cultured in a prepared culture medium and inoculated into the heap. The redox potential is then controlled to the appropriate range by adjusting the ratio of iron-oxidizing bacteria to sulfur-oxidizing bacteria in the leaching bacterial community, the aeration rate within the heap, the pH value within the heap, and the iron concentration in the leachate. This improves the copper leaching rate and extraction yield of the copper sulfide ore. Experimental results show that, in the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided in this embodiment of the invention, the copper leaching rate of copper sulfide ore reaches as high as 83.50% after dynamic potential-controlled bio-heap leaching operation. Compared with various conventional heap leaching processes, the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided by this invention can increase the copper leaching rate by more than 5% and shorten the leaching cycle by about 1 / 6, effectively improving the copper leaching rate and leaching speed of copper sulfide ore and realizing the resource utilization of low-grade copper sulfide ore.

[0055] The process of this invention is suitable for processing low-grade copper sulfide ore resources, and the redox potential of the bio-heap leaching process can be adapted according to the differences in copper phase composition in different ores, thereby improving the copper leaching rate and copper leaching percentage.

[0056] The process of this invention regulates the redox potential of the heap leaching process to a suitable range by comprehensively controlling the ratio of iron-oxidizing bacteria to sulfur-oxidizing bacteria in the inoculated bacterial culture, the amount of aeration in the heap, the pH value in the heap, and the iron element concentration in the leachate. The regulation is highly precise, has a fast response speed, and is low in cost and environmentally friendly.

[0057] This invention has advantages such as low investment, simple operation, low production cost, and green and clean process. It is particularly suitable for processing low-grade copper sulfide ore, which can improve the comprehensive utilization efficiency of this type of resource, reduce environmental pollution, and improve economic benefits, and has good application prospects. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0059] Figure 1 A flow chart of the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided in an embodiment of the present invention is shown.

[0060] Figure 2 This invention provides an operational flowchart for determining the suitable range of redox potential in low-grade copper sulfide ore.

[0061] Figure 3 The diagram illustrates the operation flow chart of the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided in an embodiment of the present invention. Detailed Implementation

[0062] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0063] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. The same reference numerals in the figures represent the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically independent entities.

[0064] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0065] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0066] Existing bio-heap leaching processes for copper sulfide ores cannot precisely control the redox potential to a suitable range during the heap leaching process, leading to problems such as unreasonable leaching parameters, low copper leaching rate and yield, and limited resource utilization of low-grade copper sulfide ores. This invention proposes a potential-controlled bio-heap leaching process for low-grade copper sulfide ores. The process involves analyzing the copper phase composition of the low-grade copper sulfide ore and determining the suitable redox potential range for the bio-heap leaching process based on the analysis results. Then, bacteria are cultured in a prepared culture medium and inoculated into the heap after ore stacking. Next, the redox potential during the heap leaching process is controlled to the suitable range by adjusting the ratio of iron-oxidizing bacteria to sulfur-oxidizing bacteria in the leaching bacterial community, the aeration rate in the heap, the pH value in the heap, and the iron concentration in the leachate, thereby improving the copper leaching rate and yield of the copper sulfide ores. In the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided in this application embodiment, the copper leaching rate of the copper sulfide ore reaches as high as 83.50% after dynamic potential-controlled bio-heap leaching operation. Compared with various conventional heap leaching processes, the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided by this invention can increase the copper leaching rate by more than 5% and shorten the leaching cycle by about 1 / 6, effectively improving the copper leaching rate and leaching speed of copper sulfide ore and realizing the resource utilization of low-grade copper sulfide ore. Furthermore, the entire process is simple to operate, low in cost, and environmentally friendly, showing good application prospects. Specific implementation methods are as follows:

[0067] In a first aspect, the present invention provides a potential-controlled bio-heap leaching process for low-grade copper sulfide ore. Figure 1 The following is a flow chart of the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided in an embodiment of the present invention, as shown in the figure. Figure 1 As shown, the process includes the following steps:

[0068] S1. The copper phase composition of the low-grade copper sulfide ore is analyzed, and the appropriate range of redox potential is determined based on the analysis results. Then, the ore is crushed to a particle size of less than 1000 mm, sulfuric acid is added and mixed evenly, and then piled up.

[0069] In this specific implementation step, the selected low-grade copper sulfide ore is at least one of chalcocite, covellite, bornite, chalcopyrite, chalcopyrite, tetrahedrite, arsenopyrite, and arsenic chalcopyrite, and the copper grade of the copper sulfide ore is greater than or equal to 0.10%. Based on the amount of target copper sulfide ore, the sulfuric acid consumption of the ore is calculated, and phase analysis is performed on the target copper sulfide ore to determine the suitable range of redox potentials for the biological oxidation and dissolution of copper minerals; the copper phase composition includes copper in copper oxide, copper in secondary copper sulfide, copper in primary copper sulfide, and copper in silicates. Figure 2 The following is a flowchart illustrating the operation of determining the suitable range of redox potential in low-grade copper sulfide ore according to an embodiment of the present invention. Figure 2 As shown, when the proportion of primary copper sulfide phase in the ore is greater than or equal to 70%, the suitable redox potential range for copper mineral dissolution is 360–460 mV vs. Ag / AgCl; when the proportion of secondary copper sulfide phase in the ore is greater than or equal to 70%, the suitable redox potential range for copper mineral dissolution is 460–520 mV vs. Ag / AgCl; when the proportion of both secondary and primary copper sulfide phases in the ore is less than 70%, the suitable redox potential range for copper mineral dissolution is divided into two stages: the suitable redox potential range for the first stage of the heap leaching process is 460–520 mV vs. Ag / AgCl, and the suitable redox potential range for the second stage of the heap leaching process is 360–460 mV. vs. Ag / AgCl; the first stage of the heap leaching process refers to the time period from the start of heap leaching until the copper leaching amount in the ore reaches 80% of the copper content in the secondary copper sulfide of the ore; the second stage of the heap leaching process refers to the time period from the time the copper leaching amount in the ore reaches 80% of the copper content in the secondary copper sulfide of the ore until the end of heap leaching. After determining the appropriate range of sulfuric acid consumption and redox potential for copper mineral dissolution, the copper sulfide ore is crushed to a particle size within 1000mm and piled up. After piling, sulfuric acid is added and sprayed evenly onto the ore pile, and the pH is adjusted to 1-2; the amount of sulfuric acid used is 1% to 100% of the total sulfuric acid consumption in this process. During piling, temperature probes, oxygen partial pressure probes, pH probes, redox potential probes, and aeration pipes are pre-embedded in the pile to monitor the real-time conditions inside the pile.

[0070] S2. Prepare a culture medium to cultivate leaching bacteria composed of iron-oxidizing bacteria and sulfur-oxidizing bacteria, and inoculate the pile.

[0071] In this step, the main energy source of the culture medium is ferrous sulfate, sulfur powder, and sulfide mineral powder. Specifically, the ferrous sulfate is at least one of ferrous sulfate, ferrous sulfate monohydrate, and ferrous sulfate heptahydrate; the sulfide mineral is at least one of pyrite, marcasite, pyrrhotite, arsenopyrite, chalcocite, covellite, chalcopyrite, chalcopyrite, tetrahedrite, arsenopyrite, and arsenic chalcopyrite. Leaching bacteria composed of iron-oxidizing and sulfur-oxidizing bacteria are cultured in the prepared culture medium. The cultured leaching bacteria are then inoculated into the constructed ore pile by spraying to carry out bioleaching. Under the action of sulfuric acid, oxygen, and leaching bacteria, the copper minerals in the copper sulfide ore are oxidized and dissolved into copper ions, which are released into the leachate, resulting in a copper-containing leachate. The copper-containing leachate circulates continuously in the ore heap leaching system. Generally, when the copper ion concentration in the copper-containing leachate reaches above 1 g / L, the enriched copper-containing leachate is passed into the extraction electrowinning workshop for further processing to extract copper and obtain qualified copper products. The low-concentration copper ion solution remaining after copper extraction is collected as raffinate for later use. The iron-oxidizing bacteria are at least one of *Acidithiobacillus ferrooxidans*, *Leptospirillum ferrooxidans*, and *Leptospirillum ferriphilum*; the sulfur-oxidizing bacteria are at least one of *Acidithiobacillus thiooxidans*, *Acidithiobacillus caldus*, and *Sulfobacillus sp.*. In some cases, when the copper ion concentration in the copper-containing leachate is below 1 g / L, the enriched copper-containing leachate can also be passed into the extraction electrowinning workshop for further processing to extract copper. Based on practical needs, some extraction operations even require a higher concentration of copper ions in the copper-containing leachate. In particular, in addition to the extraction of copper in the extraction electrodeposition workshop, the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided in this application can continuously circulate the copper-containing leachate in the ore heap leaching system, thereby enriching the copper ion concentration in it. Then, copper or copper sulfate can be extracted from the copper-containing leachate by iron powder replacement or evaporation crystallization.

[0072] S3. By controlling the ratio of iron-oxidizing bacteria to sulfur-oxidizing bacteria in the leaching bacterial community, the amount of aeration in the pile, the pH value in the pile, and the iron concentration in the leachate, the redox potential during the heap leaching process is adjusted to the appropriate range until the heap leaching is completed.

[0073] In this specific implementation step, the probes pre-embedded in step S1 are used to monitor in real time the pH, aeration volume, oxygen content, redox potential, and the proportion of iron-oxidizing and sulfur-oxidizing bacteria in the leaching bacterial community during the heap leaching process. Based on the difference between the real-time monitored potential and the target potential, parameters such as the ratio of iron-oxidizing and sulfur-oxidizing bacteria in the leaching bacterial community, the aeration volume, the pH value, and the iron concentration in the leachate are adjusted to keep the redox potential in the heap within a suitable range for the biological oxidation and dissolution of copper minerals.

[0074] Specifically, when the redox potential during heap leaching is below a suitable range, at least one of the following methods can be used to increase the redox potential: increase the aeration rate in the heap to 0.001 m³ per ton of ore. 3 / h~0.08m 3 The process involves: adding sulfuric acid solution to the circulating copper-containing leaching solution to lower the pH of the heap to between 1.00 and 1.50; neutralizing the raffinate and returning it to the heap leaching system to reduce the iron concentration of the leaching solution to between 0 and 3 g / L; increasing the proportion of iron-oxidizing bacteria in the inoculum to over 80%; and reducing the proportion of sulfur-oxidizing bacteria in the inoculum to below 10%. Specifically, increasing the proportion of iron-oxidizing bacteria in the inoculum can be achieved through at least one of the following methods: increasing the ferrous ion content in the culture medium to over 3 g / L; reducing the total content of sulfur powder and sulfide mineral powder in the culture medium to 0%–0.1%; increasing the oxygen content of the bacterial culture solution to over 3 mg / L; and controlling the pH range of the bacterial culture solution to between 1.0 and 1.50. The proportion of sulfur-oxidizing bacteria in the inoculum can be reduced by at least one of the following methods: increasing the ferrous ion content in the culture medium to above 3 g / L; reducing the total content of sulfur powder and sulfide mineral powder in the culture medium to below 0.1%; and controlling the pH range of the bacterial culture solution to 1.00–1.50 during the bacterial culture process.

[0075] It is important to note that to ensure the smooth operation of the heap leaching process, the flow rate of the leachate dissolving copper minerals needs to be monitored in real time. During the heap leaching cycle, the amount of leachate may decrease. In this case, the spray rate of the ore heap can be increased by adding water, sulfuric acid, or pit water (containing copper sulfate), or raffinate, thereby increasing the amount of leachate. In some regions or under extreme climatic conditions, the amount of leachate may increase during the heap leaching cycle. In such cases, a portion of the raffinate after leachate extraction can be diverted from the heap leaching circulation system and stored for later use.

[0076] When the redox potential during heap leaching is higher than a suitable range, at least one of the following methods can be used to reduce the redox potential: reduce the aeration rate in the heap to 0.02 m³ / ton of ore. 3The concentration of iron oxidizing bacteria in the inoculum is reduced to below 1.50 g / L; the raffinate is neutralized and returned to the heap leaching system to increase the pH of the heap to between 1.50 and 2.00; sulfate containing ferrous or ferric ions is added to the leachate to increase the iron concentration of the leachate to between 3 and 8 g / L; the proportion of iron oxidizing bacteria in the inoculum is reduced to below 10%; the proportion of sulfur oxidizing bacteria in the inoculum is increased to above 80%; wherein, the method of reducing the proportion of iron oxidizing bacteria in the inoculum is at least one of the following: reducing the ferrous ion content in the culture medium to below 3 g / L; increasing the total content of sulfur powder and sulfide mineral powder in the culture medium to 0.1% to 0.5%; reducing the oxygen content of the bacterial culture solution to below 3 mg / L (including 3 mg / L); and controlling the pH range of the bacterial culture solution to between 1.50 and 2.00. The method to increase the proportion of sulfur-oxidizing bacteria in the inoculum is at least one of the following: reducing the ferrous ion content in the culture medium to below 3 g / L; increasing the total content of sulfur powder and sulfide mineral powder in the culture medium to 0.1% to 0.5%;

[0077] The pH range of the bacterial culture solution was controlled between 1.50 and 2.00 during the bacterial culture process. Through real-time potential-controlled bio-heap leaching, the copper leaching rate of low-grade copper sulfide ore reached as high as 83.50%. Compared with various conventional heap leaching processes, the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided by this invention can increase the copper leaching rate by more than 5% and shorten the leaching cycle by about 1 / 6, effectively improving the copper leaching rate and leaching speed of copper sulfide ore.

[0078] This invention achieves the effect of adjusting the redox potential during the heap leaching process by changing the concentration of iron in the leachate. This is mainly because when the iron concentration in the leachate is high, the Fe in the leachate... 2+ The chemical oxidation of Fe was inhibited, thus making Fe 3+ / Fe 2+ Fe in redox couple 2+ The higher proportion of ferrous salts (including ferrous and ferric salts) significantly inhibits the growth and metabolism of leaching microorganisms, especially leaching bacteria that perform iron oxidation. Therefore, increasing the iron concentration in the leachate (by adding sulfates containing ferrous or ferric ions) inhibits both the growth of iron-oxidizing bacteria and their ferrous oxidation function, making it more difficult for ferrous ions in the leachate to be oxidized, thus lowering the redox potential of the leachate.

[0079] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to provide a detailed description of a potential-controlled bio-heap leaching process for low-grade copper sulfide ore according to the present invention. Figure 3 The following is a flowchart illustrating the operation of the potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided in Embodiments 1-3 of the present invention.

[0080] Example 1

[0081] This invention was used to perform a bio-heap leaching process on a low-grade copper sulfide ore. The average copper grade of the ore fed into the heap was 0.31%, and the ore quantity was 5143.29 tons. Phase analysis showed that 80.81% of the copper existed in the form of secondary copper sulfide, therefore the suitable redox potential range was 460–520 mV vs. Ag / AgCl. Acid consumption analysis showed that the sulfuric acid consumption of the ore was 41.58 kg / t (ore). The ore was crushed to -40 mm and thoroughly mixed with a 10% sulfuric acid solution in a certain proportion before being piled up. The amount of sulfuric acid used was 60% of the calculated total sulfuric acid consumption of the ore pile. During the heap construction, temperature probes, oxygen probes, pH probes, redox potential probes, and aeration pipes were pre-installed within the heap. A leaching microbial culture composed of *Acidithiobacillus ferrooxidans*, *Leptospirillum ferrooxidans*, *Acidithiobacillus thiooxidans*, and *Acidithiobacillus caldus* was cultivated. The culture medium consisted of ferrous sulfate heptahydrate, sulfur powder, and pyrite powder. The bacterial culture conditions were: ferrous ion concentration of 5 g / L, sulfur powder content of 0%, pyrite powder content of 0.01%, oxygen content of 3 mg / L, and pH of 1.50. The heaped ore was sprayed with a dilute sulfuric acid solution to moisten it, and the pH of the heap leaching system was adjusted to approximately 1.5. The cultured mixed bacterial solution was then sprayed onto the heaped ore for bioleaching. The heap leaching parameters were: aeration rate of 0.02 m³ / ton of ore. 3The heap pH was 1.50, and the iron concentration in the leachate was 3 g / L. The optimal redox potential range for the heap was selected as 460–520 mV vs. Ag / AgCl. During heap leaching, the redox potential and the proportions of iron-oxidizing and sulfur-oxidizing bacteria in the leachate were monitored. When the in-pile redox potential is below 460 mV vs. Ag / AgCl, based on the difference between the actual and target potentials, appropriately increase the ferrous ion concentration during bacterial culture, decrease the mass fraction of sulfur powder and pyrite powder, decrease the bacterial culture pH, and increase the oxygen content of the bacterial solution to ensure that the proportion of *Acidithiobacillus ferrooxidans* and *Leptospirillum ferrooxidans* in the inoculated solution is above 80%. Simultaneously, increase the in-pile aeration, decrease the in-pile pH, and decrease the iron concentration in the leachate. These measures aim to improve the in-pile redox potential. When the in-pile redox potential is above 520 mV vs. Ag / AgCl, based on the difference between the actual and target potentials, appropriately decrease the ferrous ion concentration during bacterial culture, increase the mass fraction of sulfur powder and pyrite powder, increase the bacterial culture pH, and decrease the oxygen content of the bacterial solution to ensure that the proportion of *Acidithiobacillus ferrooxidans* and *Leptospirillum ferrooxidans* in the inoculated solution is below 10%. The proportions of thiooxidans and Acidithiobacillus caldus were over 80%. Simultaneously, the aeration rate within the heap was reduced, the pH value within the heap was increased, and the iron concentration in the leachate was increased. These measures enhanced the redox potential within the heap. After 200 days of potential-controlled biological heap leaching, the copper leaching rate reached 83.50%. Compared with various conventional heap leaching processes, the potential-controlled biological heap leaching process for low-grade sulfide copper ore provided by this invention can increase the copper leaching rate by more than 5% and shorten the leaching cycle by approximately 1 / 6.

[0082] Example 2

[0083] This invention was used to perform a bio-heap leaching process on a low-grade copper sulfide ore. The average copper grade of the ore fed into the heap was 0.31%, and the ore quantity was 8714.37 tons. Phase analysis showed that 73.20% of the copper existed in the form of primary copper sulfide, therefore the suitable redox potential range was 360–460 mV vs. Ag / AgCl. Acid consumption analysis showed that the sulfuric acid consumption of the ore was 19.77 kg / t (ore). The ore was crushed to -30 mm and thoroughly mixed with an 8% sulfuric acid solution in a certain proportion before being piled up. The amount of sulfuric acid used was 40% of the calculated total sulfuric acid consumption of the ore pile. During the heap construction, temperature probes, oxygen probes, pH probes, redox potential probes, and aeration pipes were pre-embedded in the heap. A leaching microbial strain composed of *Acidithiobacillus ferrooxidans*, *Leptospirillum ferrooxidans*, *Acidithiobacillus caldus*, and *Sulfobacillus.sp* was cultivated. The culture medium consisted of ferrous sulfate heptahydrate and pyrite powder. The bacterial culture conditions were: ferrous ion concentration of 3 g / L, sulfur powder content of 0.01%, pyrite powder content of 0.03%, oxygen content of the bacterial solution of 3 mg / L, and pH of the bacterial solution of 1.50. The heaped ore was sprayed with a dilute sulfuric acid solution to moisten it, and the pH of the heap leaching system was adjusted to approximately 1.5. The cultivated mixed bacterial solution was then sprayed onto the heaped ore for bioleaching. The heap leaching parameters were: aeration rate of 0.02 m³ / ton of ore. 3The heap concentration was 1.50, and the iron concentration in the leachate was 3 g / L. The optimal redox potential range for the heap was selected as 360–460 mV vs. Ag / AgCl. During heap leaching, the redox potential and the proportions of iron-oxidizing and sulfur-oxidizing bacteria in the leachate were monitored. When the in-pile redox potential is below 360 mV vs. Ag / AgCl, based on the difference between the actual and target potentials, appropriately increase the ferrous ion concentration during bacterial culture, decrease the pyrite powder mass fraction, lower the bacterial culture pH, and increase the oxygen content of the bacterial solution to ensure that the proportion of *Acidithiobacillus ferrooxidans* and *Leptospirillum ferrooxidans* in the inoculated solution is above 80%. Simultaneously, increase the in-pile aeration, decrease the in-pile pH, and decrease the iron concentration in the leachate. These measures aim to improve the in-pile redox potential. When the in-pile redox potential is above 460 mV vs. Ag / AgCl, based on the difference between the actual and target potentials, appropriately decrease the ferrous ion concentration during bacterial culture, increase the pyrite powder mass fraction, raise the bacterial culture pH, and decrease the oxygen content of the bacterial solution to ensure that the proportion of *Acidithiobacillus ferrooxidans* and *Leptospirillum ferrooxidans* in the inoculated solution is below 10%. The proportion of Caldus and Sulfobacillus sp. was over 80%. Simultaneously, the aeration rate within the heap was reduced, the pH value within the heap was increased, and the iron concentration in the leachate was increased. These measures enhanced the redox potential within the heap. After 300 days of potential-controlled biological heap leaching, the copper leaching rate reached 74.39%. Compared with various conventional heap leaching processes, the potential-controlled biological heap leaching process for low-grade sulfide copper ore provided by this invention can increase the copper leaching rate by more than 5% and shorten the leaching cycle by approximately 1 / 6.

[0084] Example 3

[0085] This invention was used to perform a bio-heap leaching process on a low-grade copper sulfide ore. The average copper grade of the ore fed into the heap was 0.86%, and the ore quantity was 2374.32 tons. Phase analysis showed that 54.78% of the copper existed in the form of secondary copper sulfide, and 32.19% existed in the form of primary copper sulfide. Therefore, the suitable redox potential range for the first stage of the heap leaching process was 460–520 mV vs. Ag / AgCl, and the suitable redox potential range for the second stage was 360–460 mV vs. Ag / AgCl. Acid consumption analysis showed that the sulfuric acid consumption of the ore was 33.15 kg / t (ore). The ore was crushed to -30 mm and thoroughly mixed with a 10% sulfuric acid solution in a certain proportion before being piled up. The amount of sulfuric acid used was 50% of the calculated total sulfuric acid consumption of the ore pile. Temperature probes, oxygen probes, pH probes, redox potential probes, and aeration pipes were pre-installed in the heap during construction. A leaching microbial strain composed of *Acidithiobacillus ferrooxidans*, *Leptospirillum ferrooxidans*, *Acidithiobacillus caldus*, and *Sulfobacillus.sp* was cultivated. The culture medium consisted of ferrous sulfate heptahydrate, sulfur powder, and pyrite powder. The bacterial culture conditions were: ferrous ion concentration of 3 g / L, sulfur powder content of 0.01%, pyrite powder content of 0.03%, oxygen content of the bacterial solution of 3 mg / L, and pH of the bacterial solution of 1.50. The heaped ore was sprayed with a dilute sulfuric acid solution to moisten it, and the pH of the heap leaching system was adjusted to approximately 1.5. The cultivated mixed bacterial solution was then sprayed onto the heaped ore for bioleaching. The heap leaching parameters were: aeration rate of 0.02 m³ / ton of ore. 3The heap pH was 1.50, and the iron concentration in the leachate was 3 g / L. The optimal redox potential range for the first stage was 360–460 mV vs. Ag / AgCl, and for the second stage, it was 460–520 mV vs. Ag / AgCl. The first stage lasted until the copper leaching rate reached 43.82%, and the second stage lasted after reaching 43.82%. During heap leaching, the redox potential and the proportions of iron-oxidizing and sulfur-oxidizing bacteria in the leaching solution were monitored. When it is necessary to increase the redox potential within the pile, based on the difference between the actual and target potentials, appropriately increase the ferrous ion concentration during bacterial culture, decrease the mass fraction of sulfur powder and pyrite powder, decrease the pH value of bacterial culture, and increase the oxygen content of the bacterial solution to ensure that the proportion of *Acidithiobacillus ferrooxidans* and *Leptospirillum ferrooxidans* in the inoculated bacterial solution is above 80%. Simultaneously, increase the pile aeration rate, decrease the pile pH value, and decrease the iron concentration in the leachate. These measures will increase the redox potential within the pile. Conversely, when it is necessary to decrease the redox potential within the pile, based on the difference between the actual and target potentials, appropriately decrease the ferrous ion concentration during bacterial culture, increase the mass fraction of sulfur powder and pyrite powder, increase the pH value of bacterial culture, and decrease the oxygen content of the bacterial solution to ensure that the proportion of *Acidithiobacillus ferrooxidans* and *Leptospirillum ferrooxidans* in the inoculated bacterial solution is below 10%. The proportion of Caldus and Sulfobacillus sp. was over 80%. Simultaneously, the aeration rate within the heap was reduced, the pH value within the heap was increased, and the iron concentration in the leachate was increased. These measures enhanced the redox potential within the heap. After 300 days of potential-controlled biological heap leaching, the copper leaching rate reached 78.19%. Compared with various conventional heap leaching processes, the potential-controlled biological heap leaching process for low-grade sulfide copper ore provided by this invention can increase the copper leaching rate by more than 5% and shorten the leaching cycle by approximately 1 / 6.

[0086] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0087] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0088] The above provides a detailed description of a potential-controlled bio-heap leaching process for low-grade copper sulfide ore provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A potential-regulated bioheap leaching process for low-grade copper sulfide ores, characterized in that, The process comprises the following steps: S1, copper phase composition analysis is performed on the low-grade copper sulfide ore, and a suitable range of oxidation-reduction potential is determined based on the analysis results, then the ore is crushed to a particle size of 1000 mm, sulfuric acid is added and mixed uniformly, and then heap building is performed; S2, a culture medium is prepared, leaching bacteria composed of iron-oxidizing bacteria and sulfur-oxidizing bacteria are cultured, and inoculation is performed in the heap; S3, by controlling the proportion of iron-oxidizing bacteria and sulfur-oxidizing bacteria in the leaching bacteria community, the aeration amount in the heap, the pH value in the heap, and the iron element concentration of the leaching solution, the oxidation-reduction potential in the heap leaching process is controlled to the suitable range of oxidation-reduction potential until the heap leaching is completed; In step S1, the suitable range of oxidation-reduction potential is determined by the copper phase composition of the ore; when the proportion of primary copper sulfide phase in the ore is greater than or equal to 70%, the suitable range of oxidation-reduction potential is 360-460 mV vs. Ag / AgCl; When the proportion of secondary copper sulfide phase in the ore is greater than or equal to 70%, the suitable range of oxidation-reduction potential is 460-520 mV vs. Ag / AgCl; When the proportion of secondary copper sulfide or primary copper sulfide phase in the ore is less than 70%, the suitable range of oxidation-reduction potential in the first stage of the heap leaching process is 460-520 mV vs. Ag / AgCl, and the suitable range of oxidation-reduction potential in the second stage of the heap leaching process is 360-460 mV vs. Ag / AgCl; The first stage of the heap leaching process refers to the time period from the start of heap leaching until the copper leaching amount of the ore reaches 80% of the copper content of the secondary copper sulfide in the ore; the second stage of the heap leaching process refers to the time period from the copper leaching amount of the ore reaching 80% of the copper content of the secondary copper sulfide to the end of the heap leaching; The control of the oxidation-reduction potential in the heap leaching process in step S3 includes increasing / decreasing the oxidation-reduction potential in the heap leaching process; The increase of the oxidation-reduction potential in the heap leaching process is achieved by at least one of the following ways: S31, increase the amount of gas in the stack to 0.001 m3per ton of ore 3 / h~0.08 m 3 / h between; S32, reducing the pH in the heap to 1.00-1.50; S33, reducing the iron element concentration of the leaching solution to 0-3 g / L; S34, increasing the proportion of iron-oxidizing bacteria in the inoculum to more than 80%; S35, reducing the proportion of sulfur-oxidizing bacteria in the inoculum to less than 10%; The decrease of the oxidation-reduction potential in the heap leaching process is achieved by at least one of the following ways: a. reducing the amount of gas injected into the heap to 0.02 m3 per ton of ore 3 or less; b, increasing the pH in the heap to 1.50-2.00; c, increasing the iron element concentration of the leaching solution to 3-8 g / L; d, reducing the proportion of iron-oxidizing bacteria in the inoculum to less than 10%; e, increasing the proportion of sulfur-oxidizing bacteria in the inoculum to more than 80%.

2. The process according to claim 1, characterized in that, In step S1, during the heap building, temperature probes, oxygen partial pressure probes, pH probes, oxidation-reduction potential probes, and aeration pipelines are pre-embedded in the heap; The low-grade copper sulfide ore has a copper grade of greater than or equal to 0.10%; The copper sulfide ore is at least one of chalcocite, blue copper, bornite, chalcopyrite, parasympathy, tetrahedrite, arsenic tetrahedrite, and enargite. The copper phase composition components include copper in copper oxide, copper in secondary copper sulfide, copper in primary copper sulfide, and copper in silicate; The sulfuric acid dosage accounts for 1% to 100% of the total sulfuric acid consumption of the heap leaching process.

3. The process of claim 1, wherein, In step S2, the iron-oxidizing bacteria are at least one of Acidithiobacillus ferrooxidans , Leptospirillum ferrooxidans , Leptospirillum ferriphilum . The sulfur-oxidizing bacteria are at least one of Acidithiobacillus thiooxidans , Acidithiobacillus caldus , Sulfobacillus.sp . The main energy substance of the culture medium is a ferrous ion-containing sulfate, sulfur powder, and mineral powder of a sulfide mineral; The sulfide mineral is at least one of pyrite, marcasite, pyrrhotite, arsenopyrite, chalcocite, bornite, chalcopyrite, tetrahedrite, tenorite, tennantite, and enargite; The ferrous ion-containing sulfate is at least one of ferrous sulfate, ferrous sulfate monohydrate, and ferrous sulfate heptahydrate.

4. The process of claim 1, wherein, In step S34, the way to increase the proportion of iron-oxidizing bacteria in the inoculated bacterial solution is at least one of the following: 1) increasing the content of ferrous ions in the culture medium to more than 3 g / L; 2) reducing the total content of sulfur powder and sulfide mineral powder in the culture medium to 0% to 0.1%; 3) increasing the oxygen content of the bacterial solution during the bacterial culture process to more than 3 mg / L; 4) controlling the pH range of the bacterial solution during the bacterial culture process to be 1.0 to 1.

50.

5. The process of claim 1, wherein, In step S35, the way to reduce the proportion of sulfur-oxidizing bacteria in the inoculated bacterial solution is at least one of the following: 1) increasing the content of ferrous ions in the culture medium to more than 3 g / L; 2) reducing the total content of sulfur powder and sulfide mineral powder in the culture medium to less than 0.1%; 3) controlling the pH range of the bacterial solution during the bacterial culture process to be 1.00 to 1.

50.

6. The process of claim 1, wherein, In step d, the way to reduce the proportion of iron-oxidizing bacteria in the inoculated bacterial solution is at least one of the following: 1) reducing the content of ferrous ions in the culture medium to less than 3 g / L; 2) increasing the total content of sulfur powder and sulfide mineral powder in the culture medium to 0.1% to 0.5%; 3) reducing the oxygen content of the bacterial solution during the bacterial culture process to less than 3 mg / L; 4) controlling the pH range of the bacterial solution during the bacterial culture process to be 1.50 to 2.

00.

7. The process of claim 1, wherein, In step e, the way to increase the proportion of sulfur-oxidizing bacteria in the inoculated bacterial solution is at least one of the following: 1) reducing the content of ferrous ions in the culture medium to less than 3 g / L; 2) increasing the total content of sulfur powder and sulfide mineral powder in the culture medium to 0.1% to 0.5%; 3) controlling the pH range of the bacterial solution during the bacterial culture process to be 1.50 to 2.00.

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