Method for regulating copper extraction in a low-grade primary copper ore bioleaching process

Abstract

The application provides a method for regulating copper extraction in a low-grade primary copper ore bioleaching process, which comprises the following steps: adopting leaching bacteria (Leptospirillum sp. and Acidiphilium sp., the relative abundance is greater than or equal to 20% and 10% respectively) to perform first cycle leaching on a low-grade primary copper ore; adjusting (increasing) the leaching temperature after the first cycle leaching reaches the maximum leaching limit; adopting thermophilic leaching bacteria (Sulfobacillus sp., the relative abundance is greater than or equal to 15%) to continue the second cycle leaching on the low-grade primary copper ore until the leaching endpoint is reached. The application effectively improves the bioleaching efficiency of chalcopyrite mineral phase in the second cycle leaching process by regulating the bioleaching process in stages, and solves the problems of low chalcopyrite mineral phase dissolution rate and low total copper leaching rate in the primary copper ore in the process of leaching the primary copper ore by using conventional wet leaching and bioleaching methods. In addition, the application adopts an extraction iron removal method to control the concentration of ferric iron generated in the leaching process, reduces the generation of the passivation layer on the surface of the ore, and accelerates the copper leaching rate.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and in particular to a method for regulating copper extraction during the bioleaching process of low-grade primary copper ore. Background Technology

[0002] my country has relatively few large copper mines, but many are small and medium-sized, and most of them have low copper grades and complex associated mineral relationships. Among the proven copper resources, low-grade copper ore (Cu grade less than 0.5%) reserves amount to over 20 million tons of copper metal, and the vast majority are primary sulfide copper ores. Traditional flotation-smelting processes are complex, costly, and difficult to fully recover. With the continuous development of easily mined copper resources in my country, the copper grade of the ore is declining. Therefore, it is urgent to accelerate the development of my country's low-grade primary sulfide copper ore resources, achieve economical and efficient development, and ensure the country's copper resource security.

[0003] Bioleaching technology offers significant advantages in processing low-grade copper sulfide ores. Bioleaching in particular, compared to traditional copper flotation-smelting processes, boasts shorter process flows, lower investment costs, flexible production scale, and greater process applicability. Furthermore, bioleaching eliminates grinding and pyrometallurgical processes, greatly reducing operating costs and carbon emissions during copper extraction, thus minimizing impact on ecologically fragile areas. However, the ore heap in bioleaching is a complex porous medium, and current understanding of its internal structure, including solution flow and mass transfer mechanisms, is limited. Therefore, there are no effective means to control the bioleaching process. Additionally, the bioleaching of primary copper ores during the primary copper sulfide process results in a distinct elemental sulfur-iron alum passivation layer on the surface of chalcopyrite and other primary copper sulfide minerals, which affects the bioleaching rate and further impacts copper extraction. At present, the biological heap leaching process is used to leach low-grade primary copper sulfide ore. During the 6-month heap leaching cycle, the copper leaching rate is less than 50%, and even as low as 10% to 20%.

[0004] Therefore, the aforementioned problems have resulted in low leaching efficiency and long leaching cycles in the bioleaching of low-grade primary copper ore (Cu grade less than 0.5%), which has become a major bottleneck restricting the development and promotion of this technology. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention achieves the goal of extracting copper from low-grade primary copper ore by regulating the bioleaching process, thereby shortening the copper leaching cycle, accelerating the copper bioleaching rate, and realizing the efficient recovery of low-grade copper resources from ore.

[0006] The specific details of the invention are as follows:

[0007] This invention provides a method for regulating copper extraction during the bioleaching process of low-grade primary copper ore, the method comprising:

[0008] The first leaching bacterial solution was inoculated into the leaching solution with a pH of 0.5–2.5 at a bacterial solution volume / low-grade primary copper ore mass ratio of 0.1–1 L / kg, and used for leaching at a rate of 10 L / h·m 2 ~30L / h·m 2 Low-grade primary copper ore with a spray particle size of -8mm to -20mm was subjected to the first cycle leaching of copper. During the leaching process, the first redox potential value and copper ion concentration C of the leaching solution were determined with a detection cycle of m. i When the first redox potential value is greater than 500mV, the leaching time T is used as the leaching time. i For C i Find the first derivative C' i And draw C' i For T i The curve is defined as K, which is the slope of a straight line drawn on the curve through any two points.

[0009] When K1 is greater than K2, starting from day i+m+1 of leaching, the internal temperature of the leachate and the remaining low-grade primary copper ore is increased to 40℃~50℃; the second leaching bacteria solution is inoculated into the leachate at a ratio of bacteria volume to remaining low-grade primary copper ore mass of 0.1-1 L / kg, and then inoculated at a rate of 5 L / h·m 2 ~20L / h·m 2 The spraying rate continues for a second copper leaching cycle. During the leaching process, the second redox potential and copper ion concentration C of the leaching solution are determined with n as the detection period. i When C j With C j+n The absolute value of the difference is less than C j+n When the concentration reaches 1%, the second leaching cycle is suspended for 3 days starting from the (j+n+1)th cycle, followed by spraying for 4 days, and C is examined again. j+n+1 With C j+n+7 The absolute value of the difference, if the absolute value is still less than C j+n+7 If the concentration is 1%, leaching will stop, and the resulting leachate will be used for copper recovery.

[0010] Where i represents the i-th day of leaching, j represents the j-th day of leaching, and K1 represents (C' i+m -C' i ) / (T i+m -T i K2 represents (C' i -C' i-m ) / (T i -T i-m m represents days 1-7, and n represents days 1-14;

[0011] The first leaching bacterial solution includes Leptospirillum sp. and Acidiphilium sp.;

[0012] The relative abundance of Leptospirillum sp. is ≥20%;

[0013] The relative abundance of Acidiphilium sp. is ≥10%;

[0014] The second leaching bacterial solution includes Sulfobacillus sp. with a relative abundance of ≥15%.

[0015] Optionally, before inoculating the first leaching bacteria solution, the method further includes:

[0016] A sulfuric acid solution with a pH of 0.5–2.0 was used as the leaching solution, at a rate of 20 L / h·m 2 ~40L / h·m 2 The low-grade primary copper ore is leached by a cyclic spray at a certain rate. During the cyclic spraying process, sulfuric acid is used to adjust the pH of the leaching solution until the pH is stable and not greater than 2.5.

[0017] Optionally, before inoculating the first leaching bacteria solution, the method further includes:

[0018] The copper, iron, and sulfur content in the low-grade primary copper ore was analyzed, and chemical phase analysis or process mineralogical analysis was performed to determine the phase distribution of copper.

[0019] Optionally, the detection methods for analyzing the content of copper, iron and sulfur elements and the concentration of copper ions in the low-grade primary copper ore include: inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission spectrometry or atomic absorption spectrometry.

[0020] The methods for chemical phase analysis or process mineralogy analysis include mineral dissociation analysis (MLA) or automated process mineralogy analysis (BPMA).

[0021] Optionally, when the second redox potential value is higher than 550mV, the method further includes: using solvent extraction to remove iron from the leaching solution used for the second leaching cycle, so that the second redox potential value is not greater than 550mV.

[0022] Optionally, the solvent extraction method includes:

[0023] Trivalent iron was extracted from the spray liquid using a saponified P204-sulfonated kerosene extraction system; wherein, P204 accounted for 15-30% of the volume of the organic phase.

[0024] In the extraction system, the O / A ratio is 1:1 to 1:4, the number of extraction stages is 3 to 6, and the extraction time is 5 minutes.

[0025] Optionally, after removing iron from the leaching solution used for the second leaching cycle by solvent extraction, the method further includes: adjusting the pH value of the iron-removed leaching solution to be no greater than 2.5, and then returning it to the spraying process for the second leaching cycle;

[0026] The pH adjustment is performed using sulfuric acid, sodium hydroxide, or lime.

[0027] Optionally, in the low-grade primary copper ore, the copper grade ranges from 0.15% to 0.5%, and the proportion of primary copper sulfide phase in the copper phase distribution is greater than or equal to 50%.

[0028] Optionally, the low-grade primary copper ore is contained in a pillar.

[0029] Optionally, the method for increasing the temperature of the low-grade primary copper ore includes:

[0030] The pillar is externally heated, and thermocouples are placed inside the pillar to measure the temperature.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] This invention provides a method for controlling copper extraction during the bioleaching process of low-grade primary copper ore. The method employs mesophilic leaching bacteria (containing *Leptospirillum* sp. and *Acidiphilium* sp.) with the ability to oxidize ferrous iron and low-valent sulfur to perform a first cycle of leaching on the low-grade primary copper ore. After reaching the maximum leaching limit in the first cycle, the leaching temperature is adjusted (increased), and a second cycle of leaching is performed using moderately thermophilic leaching bacteria (containing *Sulfobacillus* sp.) with the ability to oxidize ferrous iron and low-valent sulfur to continue leaching on the low-grade primary copper ore until the leaching endpoint is reached. This invention effectively improves the bioleaching efficiency of the chalcopyrite phase during the second cycle (second stage) by controlling the bioleaching process in two stages. This solves the problems of low chalcopyrite phase dissolution and low total copper leaching rate in primary copper ore leaching using conventional wet leaching and bioleaching methods.

[0033] In addition, the present invention uses an extraction method to control the concentration of ferric iron generated during the leaching process, thereby reducing the formation of a passivation layer on the ore surface and accelerating the copper leaching rate. Attached Figure Description

[0034] 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.

[0035] Figure 1 A flowchart illustrating the method for regulating copper extraction from low-grade primary copper ore bioleaching process according to an embodiment of the present invention is shown. Detailed Implementation

[0036] 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.

[0037] 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. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0038] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0039] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0040] 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.

[0041] This invention provides a method for regulating copper extraction during the bioleaching process of low-grade primary copper ore. Figure 1 The following is a flowchart illustrating a method for regulating copper extraction from low-grade primary copper ore bioleaching, as provided in an embodiment of the present invention. Figure 1 As shown, the method includes:

[0042] Step 1: Inoculate the first leaching bacteria solution into the leaching solution with a pH of 0.5–2.5 at a bacteria solution volume / low-grade primary copper ore mass ratio of 0.1–1 L / kg, and then apply the solution at a flow rate of 10 L / h·m 2 ~30L / h·m 2 Low-grade primary copper ore with a spray particle size of -8mm to -20mm was subjected to the first cycle leaching of copper. During the leaching process, the first redox potential value and copper ion concentration C of the leaching solution were determined with a detection cycle of m. i When the first redox potential value is greater than 500mV, the leaching time T is used as the leaching time. i For C i Find the first derivative C' i And draw C' i For T i The curve is defined as K, which is the slope of a straight line drawn on the curve through any two points.

[0043] Step 2: When K1 is greater than K2, starting from day i+m+1 of leaching, raise the internal temperature of the leachate and the remaining low-grade primary copper ore to 40℃~50℃; inoculate the second leaching bacteria solution into the leachate at a bacteria solution volume / remaining low-grade primary copper ore mass ratio of 0.1-1L / kg, and then spray at 5L / h·m 2 ~20L / h·m 2 The spraying rate continues for the second copper leaching cycle. During the leaching process, the second redox potential and copper ion concentration C of the leaching solution are determined with n as the detection period. i When C j With C j+n The absolute value of the difference is less than C j+n When the concentration reaches 1%, the second leaching cycle is suspended for 3 days starting from the (j+n+1)th cycle, followed by spraying for 4 days, and C is examined again. j+n+1 With C j+n+7 The absolute value of the difference, if the absolute value is still less than C j+n+7 If the concentration of copper reaches 1%, leaching will stop, and the resulting leachate will be used for copper recovery.

[0044] In specific implementation, this invention targets low-grade primary copper ores with a copper grade ranging from 0.15% to 0.5% and a primary copper sulfide phase ratio of greater than or equal to 50% for copper extraction via bioleaching. Before bioleaching, the copper, iron, and sulfur content in the copper ore is analyzed, and chemical phase analysis or process mineralogical analysis is performed to determine the copper phase distribution, in order to confirm the final bioleaching effect.

[0045] In practice, to improve the adaptability of leaching bacteria to the working environment, acclimatization is required before inoculating the first and second leaching bacterial solutions. This includes: grinding low-grade primary copper ore and preparing a slurry with water to a concentration of 2wt%–10wt%; and then acclimatizing the leaching bacteria that make up the first and second leaching bacterial solutions. The inoculation concentration during the acclimatization process is 1×10⁻⁶. 7 The inoculum concentration should be above 10%–20% of the total slurry volume. Maintain the slurry pH at 1.0–2.5, and agitate or shake at 100–200 rpm. The acclimation period should be 7–14 days, and the acclimation temperature should be the same as the temperature at which the bacteria participate in the bioleaching process. Acclimation should continue until the bacterial concentration in the solution reaches 2 × 10⁻⁶ cells / ml. 8 When the bacterial concentration reaches 2 × 10⁶ cells / ml or higher, the domestication process is complete, and the domesticated leaching bacteria are obtained. Further, to obtain a sufficient quantity of domesticated leaching bacteria solution, the bacteria need to be cultured on a large scale. Specifically, the inoculum volume of the leaching bacteria solution should be 5%–30% of the total volume of the culture medium solution, the pH of the culture medium solution should be maintained at 1.0–2.5, the culture temperature should be the same as the temperature at which the bacteria participate in the bioleaching process, and the culture period should be 2–7 days, until the bacterial concentration in the culture medium reaches 2 × 10⁶ cells / ml. 8 If the bacterial culture medium solution contains cells / ml or higher, it can be used entirely as the inoculum for further expansion of the leaching bacteria culture; once the bacterial culture volume reaches the inoculation requirements, it can be used for inoculation.

[0046] In specific implementation, to avoid the death of leaching bacteria due to pH changes in the leaching solution during spraying, before inoculating the first leaching bacteria solution into the leaching solution with a pH of 0.5–2.5, this invention first uses a leaching solution (dilute sulfuric acid) with a pH of 0.5–2.0, at a rate of 20 L / h·m 2 ~40L / h·m 2 Low-grade primary copper ore is leached by a cyclic spray. During the cyclic spraying process, the dissolved substances will change the pH of the leaching solution. The pH of the leaching solution is adjusted with sulfuric acid until the pH is stable and not greater than 2.5. The leaching solution obtained at this time is then used for inoculation with the first leaching bacteria solution.

[0047] In practical implementation, experiments have demonstrated that mesophilic leaching bacteria composed of Leptospirillum sp. and Acidiphilium sp., which possess the ability to oxidize ferrous iron and low-valent sulfur, exhibit advantages such as short leaching time and high leaching efficiency when used for bioleaching of low-grade primary copper ore. Therefore, a first leaching bacterial solution composed of Leptospirillum sp. and Acidiphilium sp. with relative abundances of not less than 20% and 10%, respectively, is selected and inoculated into the leachate for the first cycle leaching of low-grade primary copper ore. Furthermore, a second cycle leaching is performed on the low-grade primary copper ore that has completed the first cycle leaching using moderately thermophilic leaching bacteria composed of Sulfobacillus sp. with a relative abundance of not less than 15%, which further leaches copper from the ore and improves the solubility of primary copper sulfide phases such as chalcopyrite.

[0048] In practice, to facilitate the collection and separation of leaching residue and leachate, low-grade primary copper ore can be packed into pillars for the bioleaching process. The following provides a detailed explanation of the first and second cycle leaching:

[0049] First cyclic leaching process: In this embodiment of the invention, mesophilic leaching bacteria (Leptospirillum sp. and Acidiphilium sp., with relative abundances of not less than 20% and 10%, respectively) with the ability to oxidize divalent iron and low-valent sulfur were inoculated into the leachate for cyclic spraying on low-grade primary copper ore with a particle size of -8 mm to -20 mm at a spraying rate of 10 L / h·m 2 ~30L / h·m 2 During the process, the detection cycle was m = 1-7 days to determine the first redox potential value and copper ion concentration C of the leachate. i When the first redox potential value is greater than 500mV, the leaching rate of copper in low-grade primary copper ore by mesophilic leaching bacteria slows down. At this time, the leaching time T... i For C i Find the first derivative C' i Draw C' i For leaching time T i The curve is defined as follows: K is the slope of the straight line drawn through any two points on the curve. When K1 is greater than K2, it indicates that the leaching of copper by the mesophilic leaching bacteria in the leachate has reached its endpoint under normal temperature conditions (the copper ion concentration has not increased). It should be noted that i represents the i-th day of leaching, and K1 represents (C' i+m -C' i ) / (T i+m -T i K2 represents (C' i -C' i-m ) / (T i -Ti-m ), m is from the 1st to the 7th.

[0050] After confirming the completion of the first leaching cycle and before proceeding with the second leaching cycle, the leaching solution and low-grade primary copper ore are heated to a temperature of 40℃~50℃.

[0051] Second leaching cycle: In this embodiment of the invention, a moderately thermophilic leaching bacterium with low-valence sulfur oxidation ability (Sulfobacillus sp. with a relative abundance of not less than 15%) is selected and inoculated into the heated leaching solution. This solution is then used for circulating leaching of the remaining low-grade primary copper ore at a leaching rate of 5 L / h·m. 2 ~20L / h·m 2 During the process, the second redox potential value and copper ion concentration C of the leachate were determined using a detection cycle of n = 1-14 days. j When C j With C j+n The absolute value of the difference is less than C j+n When the concentration reached 1%, it indicated that the moderately thermophilic leaching bacteria were no longer able to leach copper ions from the remaining low-grade primary copper ore. To further verify this result, the second leaching cycle was suspended for 3 days starting from the (j+n+1)th cycle, followed by 4 days of spraying, and C was examined again. j+n+1 With C j+n+7 The absolute value of the difference, if the absolute value is still less than C j+n+7 The 1% leaching rate indicates that the moderately thermophilic leaching bacteria were indeed unable to further leach copper ions from the remaining low-grade primary copper ore, thus concluding the second leaching cycle. Furthermore, during the second leaching cycle, if the second redox potential value exceeded 550 mV, it indicated that the concentration of ferric iron in the leaching solution was too high, causing a passivation layer to form on the surface of the low-grade primary copper ore. This would affect copper ion leaching, necessitating the removal of ferric iron from the leaching solution to maintain the second redox potential value below 550 mV and prevent the formation of a passivation layer on the copper ore surface. It should be noted that j represents the j-th day of leaching, and n represents days 1-14.

[0052] In specific implementation, the solvent extraction method uses a saponified P204-sulfonated kerosene extraction system to extract ferric iron from the leachate. In this system, the O / A ratio is 1:1 to 1:4, and P204 accounts for 15% to 30% of the organic phase by volume. The extraction stages are 3 to 6, and the extraction time is 5 minutes. Further back-extraction with hydrochloric acid solution yields a ferric chloride solution, which can be used to recover copper from copper-containing waste materials such as scrap metal and waste circuit boards, achieving comprehensive utilization. Specifically, back-extraction can be performed using 5 mol / L to 6 mol / L HCl, with an O / A ratio of 3:1 to 5:1, 3 to 5 back-extraction stages, and a back-extraction time of 5 minutes. The leachate after ferric iron removal, after pH adjustment (to no greater than 2.5), is used for a second leaching cycle.

[0053] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to describe in detail a method for regulating copper extraction from the bioleaching process of low-grade primary copper ore.

[0054] Example 1

[0055] The method described in this invention was used for bioleaching copper extraction from a low-grade primary copper ore deposit in the Americas. The ore had a copper grade of 0.285%, an iron content of 1.97%, and a sulfur content of 0.66%. The copper phase distribution in the ore is shown in the table below, with a copper oxidation rate of 9.02%. After crushing the ore to a particle size of -8 mm, it was loaded into a cylindrical column with a height of 800 mm and a diameter of 80 mm.

[0056] Table 1. Copper phase distribution of a low-grade primary copper deposit in the Americas.

[0057] Parting copper oxide Secondary copper sulfide Primary copper sulfide Silicate-coated copper total content / % 0.0257 0.089 0.159 0.011 0.285 Percentage / % 9.02 31.26 55.85 3.86 100.00

[0058] A dilute sulfuric acid solution with a pH of 1.0 was used at a flow rate of 30 L / h·m. 2 The ore pillar was leached at a specific leaching rate. The leachate flowing from the bottom of the pillar was collected and circulated back to the pillar, maintaining the pH of the leachate below 2.0. After the pH of the leachate stabilized, cultured leaching bacteria solution was inoculated at a rate of 0.1 L / kg ore, and cyclic bioleaching was performed to obtain copper leaching solution 1 and leaching residue 1. The relative abundances of Leptospirillum sp. and Acidiphilium sp. in the bacterial solution were 41.20% and 48.01%, respectively, and they could utilize ferrous iron, elemental sulfur, or divalent sulfur as nutrients.

[0059] The redox potential of copper leaching solution 1 was measured every 3 days, and the copper ion concentration of copper leaching solution 1 was analyzed every 10 days. After 60 days of bioleaching, the redox potential of copper leaching solution 1 exceeded 500mV, reaching 522mV, and the copper ion concentration in leaching solution 1 was 0.56g / L. Starting from the 71st day of leaching, the ore pillar was heated by electric heating to keep the internal temperature of the ore pillar within the range of 40-50℃.

[0060] The cultured leaching bacteria solution was inoculated at an inoculation rate of 0.1 L / kg ore, and cyclic bioleaching was performed to obtain copper leaching solution 2 and leaching residue 2. The relative abundance of Sulfobacillus sp. in the inoculated bacterial solution was 23.97%.

[0061] The redox potential of copper leaching solution 2 was measured every 3 days, and the copper ion concentration was analyzed every 10 days. After 96 days of bioleaching, the redox potential of copper leaching solution 2 exceeded 600mV, reaching 602mV. Iron removal was carried out by saponification P204-sulfonated kerosene extraction of copper leaching solution 2. The volume fraction of P204 in the organic phase was 15%. The extraction and back-extraction conditions were as follows: extraction ratio O / A 1:1, extraction stage 3, extraction time 5 min; back-extraction HCl concentration 6 mol / L, back-extraction ratio O / A 3:1, back-extraction stage 4, back-extraction time 5 min.

[0062] After 190 days of bioleaching, the copper ion concentration in leachate 2 reached 1.73 g / L. Starting from day 201 of leaching, leaching was stopped for 3 days, followed by 4 days of leaching. Subsequent examination of the copper ion concentration in leachate 2 showed that the concentration remained at 1.73 g / L, indicating the end of bioleaching. Calculations showed that the bioleaching rate of copper in this low-grade primary copper ore reached 60.74%.

[0063] Example 2

[0064] The method described in this invention was used to extract copper from a low-grade primary copper ore deposit in Heilongjiang Province through bioleaching. The ore contained 0.25% copper, 3.22% iron, and 0.39% sulfur. The copper phase distribution in the ore is shown in the table below, with a copper oxidation rate of 30.86%. After crushing the ore to a particle size of -8 mm, it was loaded into a cylindrical pillar with a height of 800 mm and a diameter of 80 mm.

[0065] Table 2. Copper phase distribution in a low-grade primary copper deposit in Heilongjiang Province.

[0066] Parting copper oxide Secondary copper sulfide Primary copper sulfide Silicate-coated copper total content / % 0.077 0.038 0.130 0.005 0.25 Percentage / % 30.86 15.20 52.04 1.90 100.00

[0067] A dilute sulfuric acid solution with a pH of 0.5 was used at a flow rate of 25 L / h·m. 2The ore pillar was leached at a controlled leaching rate. The leaching liquid flowing from the bottom of the pillar was collected and circulated back to the pillar, maintaining the pH of the leaching liquid below 2.0. After the pH of the leaching liquid stabilized, cultured leaching bacteria solution was inoculated at a rate of 0.3 L / kg ore for cyclic bioleaching, yielding copper leaching solution 1 and leaching residue 1. The relative abundances of Leptospirillum sp. and Acidiphilium sp. in the bacterial solution were 28.75% and 12.53%, respectively. The redox potential of copper leaching solution 1 was measured every 3 days, and the copper ion concentration was analyzed every 7 days. After 24 days of bioleaching, the redox potential of copper leaching solution 1 reached 509 mV, and the copper ion concentration in leaching solution 1 was 0.62 g / L. Starting from the 39th day of leaching, the pillar was heated electrically to maintain the internal temperature within the range of 40–50 °C.

[0068] The cultured leaching bacteria solution was inoculated at a rate of 0.3 L / kg ore, and a circulating bioleaching process was carried out to obtain copper leaching solution 2 and leaching residue 2. The relative abundance of Sulfobacillus sp. in the inoculated bacterial solution was 18.32%.

[0069] The redox potential of copper leaching solution 2 was measured every 7 days, and the copper ion concentration of copper leaching solution 2 was analyzed every 7 days. After 77 days of bioleaching, the redox potential of copper leaching solution 2 exceeded 550mV, reaching 581mV. Copper leaching solution 2 was subjected to saponification P204-sulfonated kerosene extraction to remove iron, and the extraction parameters were the same as in Example 1.

[0070] After 203 days of bioleaching, the copper ion concentration in leachate 2 reached 1.52 g / L. Starting from day 211 of leaching, leaching was stopped for 3 days, followed by 4 days of leaching. Subsequent examination of the copper ion concentration in leachate 2 showed a concentration of 1.53 g / L. The absolute value of the difference between the two was less than 1% of the latter's concentration, thus concluding bioleaching. Calculations showed that the bioleaching rate of copper in this low-grade primary copper ore reached 65.08%.

[0071] 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.

[0072] 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.

[0073] The above provides a detailed description of a method for regulating copper extraction in the bioleaching process of low-grade primary copper ore provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for regulating copper extraction during the bioleaching process of low-grade primary copper ore, characterized in that, The method includes: The first leaching bacterial solution was inoculated into the leaching solution with a pH of 0.5–2.5 at a bacterial solution volume / low-grade primary copper ore mass ratio of 0.1–1 L / kg, and used for leaching at a rate of 10 L / h·m 2 ~30 L / h·m 2 Low-grade primary copper ore with a spray particle size of -8 mm to -20 mm was subjected to the first cycle leaching of copper. During the leaching process, the first redox potential value and copper ion concentration C of the leaching solution were determined with a detection cycle of m. i When the first redox potential value is greater than 500 mV, the leaching time T is used as the leaching time. i For C i Find the first derivative C' i And draw C' i For T i The curve is defined as K, which is the slope of a straight line drawn on the curve through any two points. When K1 is greater than K2, starting from day i+m+1 of leaching, the internal temperature of the leachate and the remaining low-grade primary copper ore is increased to 40 ℃~50 ℃; the second leaching bacteria solution is inoculated into the leachate at a bacteria volume / remaining low-grade primary copper ore mass ratio of 0.1-1 L / kg, and then inoculated at 5 L / h·m 2 ~20 L / h·m 2 The spraying rate continues for a second copper leaching cycle. During the leaching process, the second redox potential and copper ion concentration C of the leaching solution are determined with n as the detection period. i When C j With C j+n The absolute value of the difference is less than C j+n When the concentration reaches 1%, the second leaching cycle is suspended for 3 days starting from the (j+n+1)th cycle, followed by spraying for 4 days, and C is examined again. j+n+1 With C j+n+7 The absolute value of the difference, if the absolute value is still less than C j+n+7 If the concentration is 1%, leaching will stop, and the resulting leachate will be used for copper recovery. Where i represents the i-th day of leaching, j represents the j-th day of leaching, and K1 represents (C' i+m -C' i ) / (T i+m -T i K2 represents (C' i -C' i-m ) / (T i -T i-m m represents days 1-7, and n represents days 1-14; The first leaching bacterial solution includes Leptospirillum sp. and Acidiphilium sp.; The relative abundance of Leptospirillum sp. is ≥20%; The relative abundance of Acidiphilium sp. is ≥10%; The second leaching bacterial solution includes Sulfobacillus sp. with a relative abundance of ≥15%; When the second redox potential value is higher than 550 mV, the method further includes: using solvent extraction to remove iron from the leaching solution used for the second cycle leaching, so that the second redox potential value is not greater than 550 mV. The solvent extraction method includes: Ferrous iron was extracted from the spray solution using a saponified P204-sulfonated kerosene extraction system; wherein P204 accounted for 15-30% of the organic phase by volume. In the extraction system, the O / A ratio is 1:1 to 1:4, the number of extraction stages is 3 to 6, and the extraction time is 5 min.

2. The method according to claim 1, characterized in that, Before inoculating the first leaching bacteria solution, the method further includes: A sulfuric acid solution with a pH of 0.5–2.0 was used as the leaching solution, at a flow rate of 20 L / h·m 2 ~40 L / h·m 2 The low-grade primary copper ore is leached by a cyclic spray at a certain rate. During the cyclic spraying process, sulfuric acid is used to adjust the pH of the leaching solution until the pH is stable and not greater than 2.

5.

3. The method according to claim 1, characterized in that, Before inoculating the first leaching bacteria solution, the method further includes: The copper, iron, and sulfur content in the low-grade primary copper ore was analyzed, and chemical phase analysis or process mineralogical analysis was performed to determine the phase distribution of copper.

4. The method according to claim 3, characterized in that, The methods for analyzing the content of copper, iron, and sulfur elements and the concentration of copper ions in the low-grade primary copper ore include: inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission spectrometry, or atomic absorption spectrometry. The methods for process mineralogy analysis include mineral liberation analysis (MLA) or automated process mineralogy analysis (BPMA).

5. The method according to claim 1, characterized in that, After removing iron from the leaching solution used for the second leaching cycle by solvent extraction, the method further includes: adjusting the pH value of the iron-removed leaching solution to be no greater than 2.5, and then returning it to the spraying process for the second leaching cycle; pH adjustment is performed using sulfuric acid, sodium hydroxide, or lime.

6. The method according to claim 1, characterized in that, In the low-grade primary copper ore, the copper grade ranges from 0.15% to 0.5%, and the proportion of primary copper sulfide phase in the copper phase distribution is greater than or equal to 50%.

7. The method according to claim 1, characterized in that, The low-grade primary copper ore is contained in pillars.

8. The method according to claim 7, characterized in that, The method for increasing the temperature of the low-grade primary copper ore includes: The pillar is externally heated, and thermocouples are placed inside the pillar to measure the temperature.

Images