Chalcopyrite bioleaching method based on synergistic effect of mechanical activation and potential regulation

Abstract

The invention discloses a chalcopyrite bioleaching method based on synergistic effect of mechanical activation and potential regulation and control, which comprises the following steps: sequentially carrying out crushing and mechanical activation pretreatment on chalcopyrite, and carrying out pulp mixing to obtain initial ore pulp; adding an acid leaching solution containing iron ions into the obtained initial ore pulp to obtain ore pulp containing ferric iron; and sulfur-oxidizing bacteria are inoculated into the obtained trivalent iron-containing ore pulp, leaching is carried out under the condition of constant temperature, and then solid-liquid separation is carried out to obtain copper-containing leachate and leached tailings. According to the method, mechanical activation pretreatment is combined with the synergistic effect of sulfur-oxidizing bacteria (Acidithiobacillus caldus) and Fe < 3 + >, the redox potential is controlled to be 300-350 mV, and the copper leaching rate is larger than or equal to 95%. According to the method, sulfur oxidizing bacteria are used for oxidizing elemental sulfur to generate sulfuric acid, potential is controlled, acid consumption is reduced, passivation is avoided, and the method has the advantages of being efficient, environmentally friendly and high in resource utilization rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineral processing and biohydrometallurgy, and particularly relates to a method for bioleaching chalcopyrite based on the synergistic effect of mechanical activation and potential regulation. Background Art

[0002] Microbial metallurgy technology has important applications in the extraction of metal sulfide ores, mainly manifested in two modes: bioheap leaching and bioagitated leaching. For the development of copper sulfide ore resources, this technology relies on the oxidative metabolism function of acidophilic microorganisms to continuously dissolve the target metal through the catalytic oxidation of divalent iron and the acidification conversion of the reduced sulfur element in sulfides. However, during the treatment of chalcopyrite, due to its high lattice stability, "passivation" occurs on the mineral surface during the leaching process, and it is difficult to maintain the dynamic balance between the control of the redox environment and the microbial metabolism efficiency, resulting in the copper leaching rate being difficult to meet the industrial demand. These technical barriers make the industrial application of chalcopyrite bioleaching difficult.

[0003] The Chinese patent application for invention with publication number CN110352256A discloses a technical solution for leaching metal sulfides based on a thionylcarbonyl functional reagent. This process uses an acidic sulfate system as the reaction medium to dissolve metal sulfides in a mixed solution containing ferric sulfate and a thionylcarbonyl compound, and finally obtains a leaching solution rich in metal ions. However, it does not consider the influence of microbial action on the leaching process, nor does it optimize the redox potential parameters of chalcopyrite. Secondly, in terms of reagent stability control, especially under unregulated oxidation potential conditions, the decomposition rate of the reagent will increase rapidly with the increase of potential, and the existing scheme has not proposed effective stabilizers or potential regulation means to inhibit this degradation process. The Chinese patent application for invention with publication number CN105861823A discloses a method for enhancing the microbial leaching of chalcopyrite. By adding pyrite and sphalerite to the chalcopyrite microbial leaching system, the pH of the solution is relatively low, the concentration of ferric ions and the redox potential are relatively high, and the oxidation and decomposition of chalcopyrite are enhanced by the synergistic effect of biological and physicochemical factors. However, the leaching rate of copper by this method is not very high, only 42.94%, and a large amount of Cu has not been effectively recovered. The Chinese patent application for invention with publication number CN118910406A discloses "a method for enhancing the bioleaching of chalcopyrite", which uses a leaching enhancer and coordinately regulates the leaching potential and the concentration of ferric ions to achieve the efficient oxidative leaching of chalcopyrite. However, this method has a relatively long leaching reaction time, and the leaching rate is about 82.8%, which is not very high.

[0004] In the prior art, chemical leaching methods rely on high-concentration Fe 3+As an oxidant, however, the leaching rate decreases due to the formation of passivation layers such as jarosite in the later stage of the reaction; although the microbial leaching method is environmentally friendly, a single strain (such as Thiobacillus ferrooxidans) is prone to inhibit mineral dissolution due to too high redox potential. Therefore, there is an urgent need to develop an efficient and low-consumption chalcopyrite leaching method to break through the bottleneck of leaching efficiency by optimizing the synergistic effect of mechanical activation parameters and microorganisms. Summary of the Invention

[0005] The purpose of the present invention is to provide a chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation. By the synergistic effect of mechanical activation pretreatment and the ferric iron composite system of Thiobacillus thiooxidans, the redox potential is controlled, significantly improving the copper leaching rate while reducing acid consumption and passivation risk.

[0006] The present invention provides a chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation, comprising the following steps:

[0007] S1. The chalcopyrite is successively crushed, mechanically activated pretreated, and slurried to obtain an initial pulp;

[0008] S2. An acidic leaching solution containing iron ions is added to the initial pulp obtained in step S1 to obtain a pulp containing ferric iron;

[0009] S3. Thiobacillus thiooxidans is inoculated into the pulp containing ferric iron obtained in step S2, and leaching is carried out under constant temperature conditions, and then solid-liquid separation is performed to obtain a copper-containing leaching solution and leaching tailings.

[0010] Further, in step S1, the particle size requirement for crushing is <0.15 mm; the conditions for the mechanical activation pretreatment are specifically: activation for 1 - 2.5 h at a rotation speed of 600 - 800 rpm; the concentration of the initial pulp obtained by slurrying is 1.0 - 2.5%;

[0011] The mechanical activation pretreatment refines the chalcopyrite particle size to the micron level.

[0012] Further, in step S2, the concentration of ferric iron ions in the pulp containing ferric iron is 0.1 - 0.3 mol / L, and the pH is 1 - 2.5.

[0013] Further, in step S3, the initial bacterial concentration of the inoculated Thiobacillus thiooxidans is 1 - 5*10 7 cells / mL.

[0014] The specific process conditions for the leaching are: reacting at a stirring intensity of 140 - 180 r / min at a temperature of 40 - 55 °C for 7 - 12 days.

[0015] The redox potential of the reaction system during the leaching is 300 - 400 mV.

[0016] Principle of the present invention:

[0017] The bioleaching efficiency of chalcopyrite is closely related to the redox potential of the solution. When the redox potential is within a suitable range, the leaching process of chalcopyrite can be further enhanced to obtain a higher leaching rate. Once the potential exceeds the range, the leaching rate of chalcopyrite decreases significantly. By adjusting the iron and sulfur oxidation abilities of microorganisms to control the redox potential within the optimal leaching range, the leaching rate of mechanically activated pretreated chalcopyrite can be further improved.

[0018] Conventional bioleaching methods use iron-sulfur oxidizing bacteria or a combination of iron-sulfur oxidizing bacteria and other strains as bioleaching strains. Iron-sulfur oxidizing bacteria have the ability to oxidize iron, continuously converting ferrous ions into ferric ions, thus keeping the potential of the leaching system at a relatively high level. Subsequently, trivalent ferric ions are used to oxidize valuable metals in chalcopyrite.

[0019] In the present invention, chalcopyrite is first pretreated by mechanical activation, which changes the crystal structure and electronic structure of chalcopyrite. Then, Acidithiobacillus caldus is used as the bioleaching strain. By oxidizing the elemental sulfur generated by the oxidation and decomposition of chalcopyrite into sulfate ions without oxidizing ferrous ions, the acidity and potential of the leaching system are dynamically adjusted to maintain the redox potential while increasing the acidity of the system.

[0020] By studying the bioleaching kinetics of chalcopyrite through diffusion reaction and chemical reaction kinetic models, it is found that when Sulfobacillus thermosulfidooxidans is used as the bioleaching strain, the bioleaching rate of chalcopyrite is controlled by internal diffusion. Sulfobacillus thermosulfidooxidans oxidizes ferrous ions into ferric ions, providing the potential of the leaching system, which in turn leads to the formation of jarosite on the surface of chalcopyrite, exacerbating the passivation of chalcopyrite and preventing ions from diffusing into the solution. When Acidithiobacillus caldus is used as the bioleaching strain, Acidithiobacillus caldus can adsorb and colonize on the surface of chalcopyrite to directly oxidize the mineral, or the extracellular polymeric substances formed by it can adsorb Fe 3+ in the solution. The complex formed by the two can oxidize chalcopyrite, and the mineral decomposition releases Fe 2+ and sulfur compounds. At the same time, Acidithiobacillus caldus cannot oxidize Fe 2+ back to Fe 3+ again, avoiding the "passivation" hindrance caused by the increase in potential; sulfur compounds can be used as energy sources by Acidithiobacillus caldus, and the decomposition of the sulfur layer on the surface of chalcopyrite exposes a fresh surface, accelerating the new round of interaction between the mineral and the oxidant.

[0021] Advantages of the present invention:

[0022] (1) Through a large number of experimental studies, the present invention has determined a process flow for synergistically enhancing the efficient bioleaching of chalcopyrite by mechanical activation and potential regulation. By mechanical activation, the reaction activity of the mineral is improved, and combined with the synergistic oxidation of sulfur-oxidizing bacteria and Fe 3+ , the copper leaching rate can reach 95.28%, realizing the efficient leaching of chalcopyrite;

[0023] (2) By using mechanical activation pretreatment and single-strain bioleaching of sulfur-oxidizing bacteria, the present invention realizes the potential control of the leaching system. The sulfur-oxidizing bacteria prevent the over-oxidation of Fe 2+ to Fe 3+ , inhibit the formation of the passivation layer, and maintain the potential within the optimal range (<400 mV vs. Ag / AgCl);

[0024] (3) The sulfur-oxidizing bacteria in the leaching system of the present invention can convert the elemental sulfur generated by the decomposition of the mineral into sulfuric acid, realizing "sulfur nourishing sulfur", reducing acid consumption, and maximizing resource utilization;

[0025] (4) The operation method of the present invention is simple and has low cost. It realizes an efficient bioleaching method for chalcopyrite and obtains a green leaching process, having significant economic value and environmental benefits, and being of great significance for reducing environmental pollution and realizing the effective utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic flow chart of the method of the present invention;

[0027] Figure 2 is a kinetic model fitting diagram for the bioleaching of chalcopyrite in the embodiment of the present invention;

[0028] Figure 3 is the influence of mechanical activation time; wherein Figure 3 (a) is the influence of mechanical activation time on the XRD of chalcopyrite, Figure 3 (b) is the influence of mechanical activation time on the crystal plane of chalcopyrite;

[0029] Figure 4 is the full-spectrum fitting refinement result of the chalcopyrite XRD pattern; wherein Figure 4 (a) is the XRD pattern obtained from the experiment and fitting of the 0.5 h group; Figure 4 (b) is the XRD pattern obtained from the experiment and fitting of the 1 h group; Figure 4 (c) is the XRD pattern obtained from the experiment and fitting of the 1.5 h group; Figure 4 (d) is the XRD pattern obtained from the experiment and fitting of the 2 h group; Figure 4 (e) is the XRD pattern obtained from the experiment and fitting of the 2.5 h group;

[0030] Figure 5 is the XRD pattern fitting error image;

[0031] Figure 6 Images showing the effect of mechanical activation time on the microstructure change of chalcopyrite; among them Figure 6 (a) Images of the grain size and microstrain of chalcopyrite under different mechanical activation times; Figure 6 (b) Images showing the effect of mechanical activation time on the unit cell parameters of chalcopyrite;

[0032] Figure 7 Diagram showing the effect of mechanical activation on the leaching system in the comparative example; among them Figure 7 (a) Leaching rate results diagrams of Comparative Examples 1-3, Figure 7 (b) Diagram of the potential change of the leaching system in Comparative Examples 1-3, Figure 7 (c) Diagram of the pH value change of the leaching system in Comparative Examples 1-3;

[0033] Figure 8 Diagram showing the effect of mechanical activation on each leaching system in the examples; among them Figure 8 (a) Influence on the leaching rate of brass Figure 8 (b) Influence on the redox potential of the system Figure 8 (c) Influence on the pH of the reaction system

[0034] Figure 9 Diagram showing the leaching results without mechanical activation in the comparative example; among them Figure 9 (a) Leaching rate results of brass Figure 9 (b) Redox potential results of the system Figure 9 (c) pH results of the reaction system. Detailed implementation manners

[0035] Example 1

[0036] After crushing the chalcopyrite sample, it was mechanically activated in a planetary ball mill at a speed of 700 rpm for 1 hour, and then adjusted to a 2% initial pulp;

[0037] A sulfuric acid solution containing ferric ions was added to the initial pulp to make the final concentration of ferric ions 0.1 mol / L and the pH 1.5, obtaining a pulp containing ferric ions;

[0038] Sulfur-oxidizing bacteria were inoculated into the obtained pulp containing ferric ions, and the initial bacterial concentration after inoculation was 1*10 7 cells / mL, and the leaching was carried out at a constant temperature of 50 °C with a stirring intensity of 150 r / min. The copper leaching rate was measured after 7 days.

[0039] The results showed that: the leaching rate was 95.28%, and the potential was maintained at around 350 mV during the leaching process. XRD analysis of the leaching residue showed that almost all the copper in chalcopyrite was dissolved.

[0040] Kinetic Experiment on Bioleaching of Chalcopyrite in Example 2

[0041] From the diffusion reaction and the chemical reaction kinetic formula

[0042] to calculate and study the bioleaching kinetics of chalcopyrite, the results are as Figure 2 shown, and the fitting results are shown in Table 1.

[0043] Table 1 Fitting Results of Kinetic Model (R 2 )

[0044]

[0045] It can be seen from Table 1 that the fitting degrees of the diffusion reaction models of the St-Fe 3+ system are all relatively high. Under the conditions of this experiment, the bioleaching rate of chalcopyrite is controlled by internal diffusion. The iron-sulfur oxidizing bacteria oxidize Fe 2+ to Fe 3+ , which increases the potential of the leaching solution, and then leads to the formation of jarosite on the surface of chalcopyrite, etc., intensifying the passivation of chalcopyrite, and related ions cannot diffuse into the solution. The fitting degrees of both the diffusion reaction and chemical reaction models of the Ac-Fe 3+ system are relatively high, then the leaching control step becomes a mixed control where both diffusion and chemical reaction exist simultaneously.

[0046] The adsorption and colonization of sulfur-oxidizing bacteria on the surface of chalcopyrite can directly oxidize the mineral, or the extracellular polymers formed by them can adsorb Fe 3+ in the solution. The complex formed by the two can oxidize chalcopyrite, and the mineral decomposition releases Fe 2+ and sulfur compounds. At the same time, sulfur-oxidizing bacteria cannot oxidize Fe 2+ to Fe 3+ again, avoiding the "passivation" hindrance caused by the potential increase; sulfur compounds can be used as energy substances by sulfur-oxidizing bacteria, and the decomposition of the sulfur layer on the surface of chalcopyrite makes it present a fresh section, accelerating the new round of interaction between the mineral and the oxidant. Therefore, both the chemical reaction between chalcopyrite and the oxidant and the internal diffusion of the products are crucial for the leaching process.

[0047] Experiment on the Influence of Mechanical Activation Time on the Microstructure of Chalcopyrite in Example 3

[0048] The chalcopyrite was pretreated by mechanical activation at a strength of 700 r / min, and the treatment times were 0.5 h, 1 h, 1.5 h, 2 h, and 2.5 h respectively. Then the XRD diffraction of the treated chalcopyrite was carried out, and the results are as Figure 3 shown, where Figure 3 (a) shows the influence of mechanical activation time on the XRD picture of chalcopyrite, Figure 3(b) shows the effect of mechanical activation time on the crystal plane of chalcopyrite.

[0049] As can be seen from Figure 3 (a), the mechanical activation time has no obvious effect on the XRD pattern of chalcopyrite. In order to better show the influence law of mechanical activation time on the diffraction peaks of chalcopyrite, the peak with the highest intensity was magnified and compared, and the results are as shown in Figure 3 (b). Figure 3 (b) The results show that with the extension of mechanical activation time, the diffraction peak intensity decreases, but the diffraction peak has no obvious broadening, and when the activation time is 1.0 h - 2.5 h, the difference in diffraction peak intensity is small.

[0050] The full-spectrum fitting refinement results of the chalcopyrite XRD pattern are as shown in Figure 4 , where Figure 4 (a) is the XRD pattern of the 0.5 h group experiment and the fitted one; Figure 4 (b) is the XRD pattern of the 1 h group experiment and the fitted one;

[0051] Figure 4 (c) is the XRD pattern of the 1.5 h group experiment and the fitted one; Figure 4 (d) is the XRD pattern of the 2 h group experiment and the fitted one; Figure 4 (e) is the XRD pattern of the 2.5 h group experiment and the fitted one; The fitting error of the XRD pattern is as shown in Figure 5 . The calculated peak shape fits well with the experimental peak shape, and the fitting error value is low. According to the fitting results, the grain size and microstrain values of chalcopyrite under different mechanical activation times are obtained, and the results are as shown in Figure 6 (a). The microstrain change range is relatively low when the mechanical activation time is between 1.0 h and 2.5 h, but it is higher than the microstrain value at the activation time of 0.5 h. The grain size further decreases with the increase of activation time, from at 0.5 h to at 2.5 h, but the change range of the grain size is small.

[0052] The effect of mechanical activation time on the unit cell parameters of chalcopyrite is as shown in Figure 6 (b). It is consistent with the microstrain change trend. The values of unit cell parameters a, c and unit cell volume v of chalcopyrite under different mechanical activation times have no obvious change.

[0053] Comparative Example 1

[0054] After the chalcopyrite sample was crushed, it was mechanically activated in a planetary ball mill at a speed of 700 rpm for 1 hour, and then adjusted to an initial pulp of 2%;

[0055] Sulfuric acid solution was added to the initial pulp, the pH was adjusted to 1.5, and it was leached at a constant temperature of 50 °C with a stirring intensity of 150 r / min. The copper leaching rate was measured after 7 days.

[0056] The results show that the leaching rate is 9.11%, the initial potential of the solution in the system increases from 262 mV to 353 mV, and then slowly decreases to 337 mV.

[0057] Comparative Example 2

[0058] After the chalcopyrite sample was crushed, it was mechanically activated in a planetary ball mill at a speed of 700 rpm for 1 hour, and then the pulp was adjusted to an initial pulp of 2%;

[0059] A sulfuric acid solution containing ferric ions was added to the initial pulp to make the final concentration of ferric ions 0.1 mol / L and the pH 1.5, and the pulp was leached at a constant temperature of 50 °C with a stirring intensity of 150 r / min. The copper leaching rate was measured after 7 days.

[0060] The results show that the leaching rate is 78.64%, the initial potential of the solution in the system drops sharply from 497 mV to 369 mV on the first day, and then slowly rises to 387 mV.

[0061] Comparative Example 3

[0062] After the chalcopyrite sample was crushed, it was mechanically activated in a planetary ball mill at a speed of 700 rpm for 1 hour, and then the pulp was adjusted to an initial pulp of 2%;

[0063] A sulfuric acid solution containing ferric ions was added to the initial pulp to make the final concentration of ferric ions 0.1 mol / L and the pH 1.5 to obtain a pulp containing ferric ions;

[0064] An iron-sulfur oxidizing bacterium was inoculated into the obtained pulp containing ferric ions, and the initial bacterial concentration after inoculation was 1*10 7 cells / mL, and the pulp was leached at a constant temperature of 50 °C with a stirring intensity of 150 r / min. The copper leaching rate was measured after 7 days.

[0065] The results show that the leaching rate is 64.21%, and the potential of the system is basically maintained at around 470 mV.

[0066] The results of Comparative Examples 1 to 3 are as Figure 5 shown, where Figure 7 (a) is the leaching rate result diagram of Comparative Examples 1 to 3, Figure 7 (b) is the potential change diagram of the leaching system of Comparative Examples 1 to 3, Figure 7 (c) is the pH change diagram of the leaching system of Comparative Examples 1 to 3.

[0067] From Figure 7 (a), it can be seen that the chalcopyrite after mechanical activation is in the sulfuric acid system of Comparative Example 1 and Fe in Comparative Example 2 3+The leaching rates in the system of = 0.1 mol / L are 9.73% and 78.64% respectively. The trend of the leaching rate of the microbial system in Comparative Example 3 is the same as that of Fe 3+ = 0.1 mol / L system, but the final leaching rate is 64.21%, with a difference of nearly 15%. As can be seen from Figure 7 (b), in the sulfuric acid system, the initial potential of the solution increased from 262 mV to 353 mV on the first day, and then slowly decreased to 337 mV. On the contrary, in the Fe 3+ = 0.1 mol / L system, the initial potential of the solution dropped steeply from 497 mV to 369 mV on the first day, and then slowly rose to 387 mV. The initial potential of the microbial system decreased less on the first day compared with the Fe3+ = 0.1 mol / L system, and then the potential basically remained near 470 mV. This is because the iron-sulfur oxidizing bacteria have the ability to oxidize iron, continuously oxidizing the generated Fe 2+ to Fe 3+ , keeping the solution potential at a high level all the time, and then using Fe 3+ to oxidize and leach the valuable metals in chalcopyrite. As can be seen from the analysis of the results of Figure 7 (c), compared with the blank group, the pH of the sterile group is above it. This is because the mechanically activated chalcopyrite consumes acid during the effective dissolution of Fe 3+ ; the iron-sulfur oxidizing bacteria can oxidize sulfur elements to sulfuric acid, making the pH value lower than the previous two. The increase in acidity should have promoted the further dissolution of chalcopyrite, but the leaching rate decreased instead, indicating that the redox potential is more important for leaching than pH.

[0068] Comparative Example 4

[0069] After the chalcopyrite sample was crushed, it was mechanically activated in a planetary ball mill at a speed of 700 rpm for 1 hour, and then the pulp was adjusted to an initial pulp of 2%;

[0070] A sulfuric acid solution containing ferrous ions and ferric ions was added to the initial pulp so that the final concentrations of ferrous ions were 0, 0.1, 0.05, 0.1 mol / L respectively, and the pH was 1.5, obtaining a group of pulps containing ferrous ions and ferric ions. Among them, the concentration of ferric ions being 0 is called the Ac group, the concentration of ferrous ions being 0.1 mol / L is called Ac-Fe 2+ , the concentration of ferrous ions and ferric ions being 0.05 mol / L is called Ac-Fe 2+ -Fe 3+ group, and the concentration of ferric ions being 0.1 mol / L is called Ac-Fe 3+ group.

[0071] Sulfur-oxidizing bacteria were inoculated into a group of pulps containing ferric ions obtained, and the initial bacterial concentration after inoculation was 1*10 7cells / mL, leach at a constant temperature of 50 °C with a stirring intensity of 150 r / min, and measure the copper leaching rate after 7 days.

[0072] As can be seen from Figure 8 (a), the final leaching rate of the Ac group is only 26.52%, although it has increased compared to the leaching rate of the sulfuric acid group, it is still very low; Mechanically activated chalcopyrite in Ac-Fe 2+ , Ac-Fe 2+ -Fe 3+ , Ac-Fe 3+ system, as the initial concentration of Fe 3+ increases, the leaching rates of each group increase in turn. Among them, the Ac-Fe 3+ group is significantly higher than other experimental groups throughout the leaching process, and the leaching rate reaches 95.28% after 7 days of leaching. As can be seen from Figure 8 (b) and 8(c), the solution potential of the Ac group remains at about 337 mV throughout the leaching process, and the pH rises from 1.5 to 2.4 all the way. The potential of the Ac-Fe 2+ group slowly rises from 336 mV to 346 mV. The solution potential of the Ac-Fe 2+ -Fe 3+ and Ac-Fe 3+ groups drops significantly to about 350 mV on the first day, and then rises and remains nearly unchanged; The pH of the Ac-Fe 2+ , Ac-Fe 2+ -Fe 3+ , Ac-Fe 3+ groups all show a trend of first increasing and then decreasing. Compared with the other two groups, the pH of the Ac-Fe 3+ group has always been at a lower level.

[0073] From the above results, it can be seen that iron-sulfur oxidizing bacteria can not only oxidize Fe 2+ in the leaching solution or on the surface of chalcopyrite into Fe 3 + , but also oxidize elemental sulfur to obtain energy, resulting in an increase in the oxidation-reduction potential and a decrease in pH; while sulfur-oxidizing bacteria only oxidize the elemental S produced by the oxidation and decomposition of chalcopyrite into sulfate ions, so it can increase the acidity of the solution while maintaining the oxidation-reduction potential. Therefore, the results show that when the potential in the solution is less than 400 mV (vs SCE), the oxidation and decomposition of chalcopyrite can be accelerated. However, once the potential exceeds the range, the leaching rate of chalcopyrite decreases significantly. In summary, we can believe that by adjusting the ferrous and sulfur oxidation abilities of microorganisms to control the oxidation-reduction potential within the optimal leaching range, the leaching rate of mechanically activated pretreated chalcopyrite can be further improved.

[0074] Compared with the chemical leaching of the Fe 3+ system and St-Fe 3+Compared with the bioleaching of the system, Ac-Fe 3+ In the bioleaching of the system, the copper in chalcopyrite is almost completely leached, and the sulfur element in chalcopyrite can be used for growth, truly achieving "feeding sulfur with sulfur" and "consuming acid to supply acid", maximizing resource utilization.

[0075] Comparative Example 5

[0076] After crushing the chalcopyrite sample, a sample with a particle size < 0.15 mm was obtained, and the pulp was adjusted to an initial pulp of 2%.

[0077] A sulfuric acid solution containing divalent iron ions and trivalent iron ions was added to the initial pulp, so that the final concentrations of iron ions were 0, 0.1, 0.05, and 0.1 mol / L respectively, and the pH was 1.5, obtaining a group of pulps containing divalent iron ions and trivalent iron ions. Among them, the trivalent iron ion concentration of 0 is called the Ac group, and the divalent iron ion concentration of 0.1 mol / L is called Ac-Fe 2+ , and the divalent iron ion and trivalent iron ion concentrations of 0.05 mol / L are called Ac-Fe 2+ -Fe 3+ group, and the trivalent iron ion concentration of 0.1 mol / L is called Ac-Fe 3+ group. And a blank control group was set up, without iron ions called the blank group, and the divalent iron ion concentration of 0.1 mol / L is called the Fe 2+ group.

[0078] Sulfur-oxidizing bacteria were inoculated into a group of pulps containing trivalent iron ions, and the initial bacterial concentration after inoculation was 1*10 7 cells / mL, and the leaching was carried out at a constant temperature of 50 °C, with a stirring intensity of 150 r / min. After 7 days, the copper leaching rate was measured.

[0079] From Figure 9 (a), it can be seen that the final leaching rates of the blank group and the Fe 2+ group without sulfur-oxidizing bacteria were 9.83% and 22.66% respectively; chalcopyrite was in Ac-Fe 2+ , Ac-Fe 2+ -Fe 3+ , Ac-Fe 3+ system, as the initial concentration of Fe 2+ increased, the leaching rates of each group increased in turn. Among them, the Ac-Fe 2+ group was higher than other experimental groups throughout the leaching process, and the leaching rate reached 40.54% after 7 days of leaching. From Figure 9 (b), it can be seen that the potential of the blank group decreased slightly from 370 mV to about 350 mV. The potential of the Ac group decreased from 350 mV to 300 mV on the first day, and then kept rising and stabilized at 550 mV; Fe 2+ group and Ac-Fe2+ During the entire leaching process, the solution potential of the group increased from about 250 mV to around 400 mV and 450 mV respectively. Ac-Fe 2+ -Fe 3+ The potential basically remained at 450 mV; for the Ac-Fe 3+ group, the solution potential always remained at a high level, above 500 mV. As can be seen from Figure 9 (c), for the Ac group and the Ac-Fe 2+ group, compared with other groups, the pH has always been at a relatively high level, above 1.8; while for the Ac-Fe 2+ -Fe 3+ and Ac-Fe 3+ groups, the pH of all three groups showed a fluctuating trend, and the pH was at a relatively low level, around 1.5. The other two groups showed mediocre performance, and the pH values were in the middle position.

[0080] From the above results, it can be seen that compared with the experimental results of the mechanically activated group, when chalcopyrite without mechanical activation pretreatment was co-leached with sulfur-oxidizing bacteria, it was found that the effect was better in the Fe 2+ leaching environment. However, as the leaching progressed, after the potential exceeded the optimal leaching range, the leaching rate of chalcopyrite decreased significantly, and the leaching rate reached 40.54%. While after chalcopyrite was mechanically activated, when leached with sulfur-oxidizing bacteria, the effect was better in the Fe 3+ leaching environment, and the leaching rate was as high as 95.28%. This shows that the mechanical activation pretreatment-Fe 3+ synergistic effect controls the potential and can efficiently improve the leaching rate of chalcopyrite.

Claims

1. A bioleaching method of chalcopyrite based on the synergistic effect of mechanical activation and potential regulation, characterized in that, It includes the following steps: S1. The chalcopyrite is successively crushed, mechanically activated and pretreated, and then slurried to obtain an initial slurry; S2. An acidic leaching solution containing iron ions is added to the initial slurry obtained in step S1 to obtain a slurry containing ferric iron; S3. Sulfur-oxidizing bacteria are inoculated into the slurry containing ferric iron obtained in step S2, and leaching is carried out under the condition of constant temperature, and then solid-liquid separation is carried out to obtain a copper-containing leaching solution and leaching tailings.

2. The chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation according to claim 1, wherein In step S1, the particle size requirement for crushing is <0.15 mm; the specific conditions for the mechanical activation pretreatment are: activation for 1-2.5 h at a rotation speed of 600-800 rpm; the concentration of the initial slurry obtained by slurrying is 1.0-2.5%.

3. The chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation according to claim 1, wherein The mechanical activation pretreatment refines the particle size of chalcopyrite to the micron level.

4. The chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation according to claim 1, wherein In step S2, the concentration of ferric iron ions in the slurry containing ferric iron is 0.1-0.3 mol / L, and the pH is 1-2.

5.

5. The chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation according to claim 1, characterized in that, In step S3, the initial bacterial concentration of the inoculated sulfur-oxidizing bacteria is 1 to 5*10 7 cells / mL.

6. The chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation according to claim 1, characterized in that, In step S3, the specific process conditions for leaching are: reacting at a stirring intensity of 140-180 r / min at a temperature of 40-55 °C for 7-12 days.

7. The chalcopyrite bioleaching method based on the synergistic effect of mechanical activation and potential regulation according to claim 1, characterized in that, The redox potential of the reaction system during leaching is 300-400 mV.

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