Ferric Leaching Research Articles

Adaptation of an iron oxidising culture to extremely high Fe concentration by a programmed fed-batch bioreactor

Ferric iron plays a key role as a leaching agent. In ferric leaching, the generated ferrous iron can be biologically regenerated by biooxidation. In commercial applications, microbial growth usually limits operational conditions such as iron concentration and pH. Therefore, design and operation are often conditioned by strict restrictions of pulp density and need of addition of alkaline reagents. In the present work a mixed culture consisting mainly of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans has been adapted to extremely high iron concentrations in comparison with the reported information in literature. For this purpose, a programmed fed-batch bioreactor has been used. A continuous stirred tank reactor was operated for testing the adapted culture. As a result, no biological inhibition was observed with iron concentrations up to 50 g·L−1 and pH of 0.7. By this methodology, an adapted inoculum can be continuously generated in order to assist industrial operations.

Comparison of sphalerite, djurleite, and chalcopyrite leaching by chemically and biologically generated ferric sulfate solutions

Ferric leaching, including the oxidation of sulfide raw materials of nonferrous metals in a ferric sulfate solution, is a well-known hydrometallurgical process that is widely applied in practice. Recent studies have indicated differences in the leaching kinetics of sphalerite concentrates when using solutions of ferric sulfate obtained by dissolving a commercial reagent or after bio-oxidation of iron-containing substrates by acidophilic chemolithotrophic microorganisms. In this research, the leaching of powder samples of natural zinc and copper sulfide minerals (sphalerite, djurleite, and chalcopyrite) was compared using two different solutions. The first one was an aqueous solution of a chemically pure ferric sulfate reagent, and the second solution contained ferric sulfate obtained via biooxidation of the chemically pure reagent of ferrous sulfate by an acidophilic bacterium Leptospirillum ferriphilum. The leaching solutions contained 10.1 g/L of ferric iron, pH 1.3. The experiments were carried out in batch mode in a mechanically stirred reactor. When using a solution of the chemical reagent of ferric sulfate, the level of dissolution of sulfide minerals was higher than in the case of the biological reagent: by 21.3% after 5 h (80 °C; 1% pulp density) for sphalerite, by 11.8% after 3 h (80 °C; 1% pulp density) for djurleite, and by 9.1% after 5 h (80 °C; 0.5% pulp density) for chalcopyrite. A comparison of the results of experiments with the biological reagent throughout from which microbial cells were preliminarily removed and the chemical reagent to which microbial cells were added confirmed the pivotal role of microbial cell lysis products in decreased efficiency of leaching with the biological reagent. Metabolomics analysis revealed several potential metabolites of L. ferriphilum involved in the observed negative effect on the leaching effectiveness, including nucleosides, alkaloids, and benzaldehydes. By contrast, the efficiency of zinc leaching from sphalerite was improved in the presence of metabolism products of L. ferriphilum in the first hours of the process.

Comparison of sphalerite concentrate leaching by chemical and microbially produced ferric sulfate

High-temperature ferric leaching is a promising method to improve the recovery of nonferrous metals from sulfide ores and concentrates. In this study, differences in the leaching kinetics of a sphalerite concentrate using chemical and biogenic ferric iron have been revealed. A comparison of leaching with a (i) biosolution containing ferric iron produced by microbial cells assigned to the strain Leptospirillum ferriphilum BUT, (ii) cell-free iron-containing L. ferriphilum culture liquid, and (iii) commercial reagent of ferric iron indicated that the latter allowed the maximum zinc and copper extraction into the solution. It is suggested that the products of the microbial cell lysis interacted with metal cations, decreasing their reactivity, and slowed down the removal of products from the reaction zone. This led to the formation of a dense layer of reaction products coating sulfide minerals. Probably, the rate of zinc and copper leaching was controlled by both the diffusion of the oxidant through a layer of the reaction products and a chemical reaction on the surface of mineral particles, indicating a mixed type of control. This pattern was independent of the chemical or biological origin of the ferric iron solution. The results provide new insights into the kinetic patterns and structural changes of sulfide minerals during ferric leaching and may contribute to the intensification of the processing of sulfide raw materials.

Comparison of Bio- and Ferric Leaching for Beneficiation of Bulk Copper-Nickel Sulfidic Concentrate

Processing of sulfidic raw materials, including bulk concentrates of nonferrous metals, is a problem of current importance in metallurgy and waste recycling. In this study, leaching with a chemical ferric iron reagent was compared to two bio-approaches to process a bulk copper-nickel concentrate: (1) ferric leaching with a solution obtained by microbial oxidation and (2) stirred-tank bioleaching using an active acidophilic microbial community. The results of both the chemical and bio-processes indicated nickel dissolution, while copper was accumulated in leach residues. After short-term high-temperature leaching with the chemical or bio- solution (Fe3+, 10 g/L), the nickel content in solids decreased by 0.7 and 2.6%, respectively, while the copper content slightly increased (by 1.5–3.2%). Bioleaching at 40°C was characterized by a considerably higher efficacy of the process: nickel leaching reached 86.7%, and the copper content increased by ~5% in the bioleach residue. Based on these results, ferric leaching can be considered an inefficient method for selective nickel removal, while bioleaching may be a promising cost-effective approach characterized by relatively low environmental hazards to obtain a high-grade copper product. Moreover, ferric leaching with the bio-solution can improve the grade of monometallic sulfidic concentrates due to additional selective nickel extraction.

Copper recovery from unground printed circuit board by biogenic ferric at high solid/liquid ratio

• Biogenic ferric sulphate leaches Cu from large PCB pieces at high solid–liquid ratio. • A bioreactor that regenerates the spent ferric ion assits the leaching. • Bioreactor operated continuously without showing inhibition problems. In this work, the recovery of Cu from large waste printed circuit board ( PCB) pieces by biogenic ferric sulphate at high solid to liquid ratio was studied. PCB parts were packed in a column and biogenic ferric was constantly recirculated. A high oxidation reduction potential (ORP) decrease was observed in ferric leaching due to ferric ion consumption; this drop caused a slower copper dissolution kinetics. After 25 days, 62.2% of copper was leached from PCBs column. PCBs column was connected to a flooded packed-bed (FPB) bioreactor to study the biological regeneration of ferric ion consumed in chemical reaction. The bioreactor connection enabled working at a constant ORP (700 mV vs. Ag/AgCl) during the whole test time. The improvement of oxidising conditions hugely increased copper dissolution rate, reaching 90% of copper recovery after 25 days. The FPB bioreactor operated continuously without showing inhibition problems and generating a leaching liquor with a high and constant ORP. The novel proposed configuration consists of a chemical reactor, where large PCBs pieces are piled at a high solid load, connected to a FPB bioreactor that regenerates the spent ferric ion enabling the leaching without reagents consumption, is a simple, inexpensive, low energy consumption, eco-friendly and effective system to recover copper from PCBs.

Chalcopyrite leaching with iodine (JX Iodine Process) for various ore types

JX Nippon Mining and Metals Corporation developed the JX Iodine Process, which is an innovative and patented copper-leaching method for low-grade primary sulfide ores. The process consists of the irrigation of ferric iron and low-concentration iodide solutions. One-meter column leaching tests were conducted on a variety of ore types. The JX Iodine Process promoted Cu recovery in several ores compared with the conventional ferric leaching method. However, the Cu recovery was less improved when the ores contained high concentrations of calcite or Cu-soluble minerals. Even among the ores in which the chalcopyrite leaching was successfully improved, there was a notable difference in the improvement rate. Microscopic observations of the post-leaching residue cross-sections showed reaction vestiges around some chalcopyrite particles and even in the inner areas of the ores with high Cu recovery, which suggests that Cu recovery is sensitive to ore permeability. Scanning electron microscope observations indicate that the reaction vestiges were composed of elemental sulfur. The results of 6-m column leaching tests with a closed solution cycle also demonstrated the effectiveness of the JX Iodine Process.

Metal Extraction and Recovery from Mobile Phone PCBs by a Combination of Bioleaching and Precipitation Processes

Bearing in mind the metal rich composition of printed circuit boards (PCBs), this material represents a secondary source of valuable metals and offers an entrepreneurial opportunity in the metal sales market. Based on the ability of microorganisms to regenerate and produce the chemical oxidants that are responsible for metal leaching, bioleaching has become an efficient and affordable alternative to conventional metal recycling technologies, although further research is still necessary before industrial implementation. This study focuses on the recovery of metals contained in mobile phone PCBs through a combined process. Two different PCB pre-treatments were evaluated: grinding the whole piece and removing the epoxy cover from the piece without grinding. The benefit of A. ferrooxidans activity on the metal solubilization rate was analyzed. Additional chemical leaching assays were also conducted for comparison purposes and the reagents ferric iron (Fe3+) and sulfuric acid (H2SO4) were selected for these experiments. The copper extraction results obtained in Fe3+ experiments with and without bacteria (A. ferrooxidans) were similar after 260 h of operation, indicating the need for alternative strategies to ensure a controlled and continuous metal biodissolution rate. The contribution of H2SO4 to the leaching processes for copper and nickel was almost negligible during the first 50 h, and more significant thereafter. The recovered metals were precipitated from a synthetic solution simulating a real ferric leaching by adding sodium hydroxide (NaOH) and sodium sulfide (Na2S). The combination of both precipitants allowed an effective removal of metals from the leachate.

Ferric Leaching of Bulk Sulfidic Concentrates with Biologically Generated Solution

Ferric Leaching of Bulk Sulfidic Concentrates with Biologically Generated Solution

A novel hydrometallurgical treatment for the recovery of copper, zinc, lead and silver from bulk concentrates

Nowadays sulphide ores exploitation is undergoing some troubles, which are hindering the treatment through traditional routes. Bulk flotation followed by a novel hydrometallurgical process can dodge these difficulties. In this work, an integral hydrometallurgical process consists of two ferric leaching steps, followed by a hot brine leaching stage, is proposed to recover target metals from a bulk sulphide concentrate (2.9% Cu, 7.4% Zn, 2.5% Pb, 67 ppm Ag and 37.2% Fe). In the first ferric leaching step, sphalerite, galena and copper secondary sulphides are dissolved and, in the second leaching step, a silver salt is added in order to catalyse chalcopyrite oxidation. If silver salt is added at the beginning of the process, sphalerite passivation is observed, and therefore zinc recovery is not possible. However, when catalytic leaching is performed after a previous ferric leaching, copper and zinc recoveries higher than 95% are achieved. The leached concentrate (0.3% Cu, 0.8% Zn, 3.3% Pb, 1438 ppm Ag, 38.0% Fe and 6.6% S0), is treated by a hot brine leaching. When hot brine leaching is performed at high pulp density, elemental sulphur removal is necessary to recover all silver added as a catalyst. Extractions higher than 95% for Zn, Cu and Pb are achieved as well as the total recovery of catalyst. The proposed process is silver surplus; therefore, this agent can be recirculated.

Sequential Bioleaching of Pyritic Tailings and Ferric Leaching of Nonferrous Slags as a Method for Metal Recovery from Mining and Metallurgical Wastes

In this work, we proposed a method for biohydrometallurgical processing of mining (old pyritic flotation tailings) and metallurgical (slag) wastes to recover gold and other nonferrous metals. Since this processing allows the removal of toxic metals or at least decreases their content in the solids, this approach may reduce the negative environmental impacts of such waste. The proposed process was based on pyritic tailings’ bioleaching to recover metals and produce leach liquor containing a strong oxidizing agent (ferric sulfate) to dissolve nonferrous metal from slag. This approach also allows us to increase concentrations of nonferrous metals in the pregnant leach solution after pyritic waste bioleaching to allow efficient extraction. The old pyritic tailings were previously leached with 0.25% sulfuric acid for 10 min to remove soluble metal sulfates. As a result, 36% of copper and 35% of zinc were extracted. After 12 days of bioleaching with a microbial consortium containing Leptospirillum spp., Sulfobacillus spp., Ferroplasma spp., and Acidithiobacillus spp. at 35 °C, the total recovery of metals from pyritic tailings reached 68% for copper and 77% for zinc; and subsequent cyanidation allowed 92% recovery of gold. Ferric leaching of two types of slag at 70 °C with the leachate obtained during bioleaching of the tailings and containing 15 g/L of Fe3+ allowed 88.9 and 43.4% recovery of copper and zinc, respectively, from copper slag within 150 min. Meanwhile, 91.5% of copper, 84.1% of nickel, and 70.2% of cobalt were extracted from copper–nickel slag within 120 min under the same conditions.

Potential of metals leaching from printed circuit boards with biological and chemical lixiviants

The generation of electronic waste (e-waste) is an issue with global consequences and therefore the proper management and recycling of e-waste are of increasing importance. Printed circuit boards (PCBs), which are a common component of e-waste, have a high valuable metal content which also makes this material an important secondary resource. In this study, biohydrometallurgical extraction of metals from PCBs was investigated as a potential alternative to conventional hydrometallurgical or pyrometallurgical processing options. An indirect non-contact leaching approach using ferric iron generated by Acidithiobacillus ferrooxidans was compared to chemical ferric sulfate leaching of Cu, Ni, Zn and Al from milled high-grade PCBs at 1% pulp density at Fe3+ concentrations of 5–20 g L−1 and at a pH range of 0.6–1.2. The roles of redoxolysis and acidolysis were examined by comparing ferric leaching with sulfuric acid leaching conducted at initial pH values of 0.8–1.4. Results showed that the supplementation of ferric iron significantly (p < 0.05) improved the chemical leaching yields as compared to sulfuric acid leaching for Cu (47.4% to 66.3%), Al (55.3% to 100%), Zn (45.5% to 92.4%) and Ni (61.0% to 97.7%) at pH 0.8. Increase in ferric iron concentration and decrease in pH also significantly (p < 0.05) improved the yield for both biological and chemical leaching. The optimal condition for overall metal bioleaching was at 20 g L−1 ferric iron at an initial pH of 0.6, yielding 87% for Cu and 100% for Al, Zn and Ni. Since no significant variation was found between chemical ferric sulfate and biogenic ferric sulfate leaching at a majority of the tested ferric concentrations, this study suggested that using biogenic lixiviants for extracting metals from PCBs is a viable alternative to chemical leaching.

Copper Recovery from Printed Circuit Boards Using Acidic Ferric Chloride Leaching and Electrodeposition

In this work, 0.5 mol L−1 HCl and 0.13 mol L−1 FeCl3 have been used as leaching solution of industrially wasted copper at room temperature. Copper recovery from the leaching solution has been studied by batch electrodeposition at room temperature and either by using different constant current densities or by pulsing the current. The deposits obtained at 20 mA cm−2 show low efficiencies and are mainly composed of Cu0 with CuCl being a minor component. When the deposits are obtained at 50 mA cm−2, the efficiency is higher, but the adherence is poor and the porosity is high. By using pulsed electrodeposition, it is possible to improve the adherence of the deposits. However, the deposits are contaminated with copper and iron oxides, as well as with chloride compounds. Tin was not detected in any of the deposits obtained using all the electrodeposition conditions tested in this work.

Distinct Roles of Acidophiles in Complete Oxidation of High-Sulfur Ferric Leach Product of Zinc Sulfide Concentrate.

A two-step process, which involved ferric leaching with biologically generated solution and subsequent biooxidation with the microbial community, has been previously proposed for the processing of low-grade zinc sulfide concentrates. In this study, we carried out the process of complete biological oxidation of the product of ferric leaching of the zinc concentrate, which contained 9% of sphalerite, 5% of chalcopyrite, and 29.7% of elemental sulfur. After 21 days of biooxidation at 40 °C, sphalerite and chalcopyrite oxidation reached 99 and 69%, respectively, while the level of elemental sulfur oxidation was 97%. The biooxidation residue could be considered a waste product that is inert under aerobic conditions. The results of this study showed that zinc sulfide concentrate processing using a two-step treatment is efficient and promising. The microbial community, which developed during biooxidation, was dominated by Acidithiobacillus caldus, Leptospirillum ferriphilum, Ferroplasma acidiphilum, Sulfobacillus thermotolerans, S. thermosulfidooxidans, and Cuniculiplasma sp. At the same time, F. acidiphilum and A. caldus played crucial roles in the oxidation of sulfide minerals and elemental sulfur, respectively. The addition of L. ferriphilum to A. caldus during biooxidation of the ferric leach product proved to inhibit elemental sulfur oxidation.

Biooxidation of High-Sulfur Products of Ferric Leaching of a Zinc Concentrate

We have previously proposed a highly efficient technology for metal recovery from low-grade zinc sulfide concentrate by two-step treatment including ferric iron leaching and biooxidation of the produced ferrous iron to ferric iron (an oxidizer for sulfide minerals). The present work proposes joint biooxidation of the products of ferric leaching of the low-grade zinc concentrate: a solution containing 24.2 g/L ferrous iron and a residue containing 29.7% elemental sulfur. Apart from regeneration of the oxidant, joint biooxidation of the solution and the residue by microbial associations including iron- and sulfur-oxidizing organisms, also prevents alkalinization of the solution, which makes it possible to omit using sulfuric acid during bioregeneration. The most efficient bioregeneration of ferric iron occurred when a mixed microbial culture was grown at 40°C. According to the results of metagenomic analysis, predominant lithotrophs in the culture belonged to the genera Leptospirillum, Sulfobacillus, Acidithiobacillus, and Ferroplasma; organotrophic Cuniculiplasma was also present. Under these conditions, the rate of ferrous iron oxidation was 5.4 g/(L day), and the oxidation level of elemental sulfur in the residue was 59.5%. The role of mixo- and organotrophic acidophilic microorganisms is discussed. They predominated in associations during bioregeneration of the oxidant, as well as in the course of the medium detoxication in order to ensure growth of the autotrophic association by utilization of organic compounds. The latter were released by autotrophs during the initial production of the ferric leaching solution and due to autolysis of microbial cells during the high-temperature ferric leaching.

Sustainable copper extraction from mixed chalcopyrite–chalcocite using biomass

Abstract This paper elaborated on the sustainability of the copper extraction process. In fact, an alternative copper extraction route from mixed sulphide ores, chalcopyrite and chalcocite using mesophilic biomass consortium at 33.3 °C and ferric leaching process were attempted. Bioleaching experiments were settled with a fraction size of −75+53 µm. Bacteria were used as the catalyst. A copper yield of 65.50% was obtained. On the other hand, in ferric leaching process, with a fraction size of −53+38 µm, when the temperature was increased to 70 °C, the copper leaching rate increased to 78.52%. Thus, comparatively, the mesophilic bioleaching process showed a more obvious advantage in copper extraction than leaching process with a high temperature. However, it has been resolved from the characterization performed using SEM−EDS, FTIR and XRD observations coupled with different thermodynamic approaches that, the indirect mechanism is the main leaching mechanism, with three transitory mechanisms (polysulphide, thiosulphate and elemental sulphur mechanisms) for the mixed chalcopyrite−chalcocite ore. Meanwhile, the speciation turns into Cu2S−CuS−Cu5FeS4−Cu2S before turning into CuSO4. While ferrous oxidation and the formation of ferric sulphate occur, and there is a formation of strong acid as bacteria digest sulphide minerals into copper sulphate at low temperature, which is why this copper production scenario requires a redox potential more than 550 mV at room temperature for high copper leaching rate.

Ferric Leaching of Low-Grade Zinc Concentrate with a Biologically Produced Solution

The process of ferric leaching of a zinc concentrate (43.3% zinc, 2.03% copper, and 13.6% iron) with a biologically produced solution has been studied. Conditions that can increase its efficiency have been found. The extraction of copper and zinc was found to increase with an increase in temperature from 25 to 80°C. The effect of pH on this process was studied, and the extraction of metals was found to decrease with a decrease in pH from 1.3 to 0.7. It was determined that the Fe3+ concentration in the leaching solution did not affect copper recovery, while zinc recovery increased with an increase in the oxidant concentration. At a solid content in the suspension of 1%, the specific zinc leaching rate was 0.86 g/(g h), and for copper this rate was 0.46 g/(g h). These values decreased to 0.54 and 0.36 g/(g h), respectively, with an increase in pulp density of up to 10%. Thus, the parameters for effective concentrate leaching were found: a temperature of 80°C, a pH of 1.3, a solid content in the suspension equal to 10%, and an initial Fe3+ concentration of 25.0 g/L. Under these conditions, four cycles of ferric leaching of the concentrate were carried out, as a result of which 92.3% of zinc and 51.6% of copper were extracted into the solution. The contents of zinc and copper in the solids decreased to 6.17 and 1.82%, respectively.

Effect of sulfide mineral content in copper-zinc concentrates on the rate of leaching of non-ferrous metals by biogenic ferric iron

The leaching of copper-zinc concentrates with different sulfide mineral content by biogenic ferric iron has been studied. It was determined that chalcopyrite, sphalerite, pyrrhotite, and pyrite were in the range of 29–55, 11–3.9, 34–14, and 12–13%, respectively. The rate of copper leaching was shown to decrease from 5.1 to 2.6 g/L/h, while its content in the concentrate decreased from 19.2 to 10.1%. The rate of zinc leaching increased from 2.9 to 5.3 g/L/h, while its content in these concentrates increased from 2.64 to 7.36%. The results indicate that the specific rates of copper leaching remained unchanged in all the concentrates studied and were within 0.20 and 0.27 g/g/h. We suggest that this was primarily associated with the dependence of this parameter on the rest potential of chalcopyrite. The specific rate of zinc leaching varied from 0.73 to 1.14 g/g/h and depended significantly on the ratio of contents of sulfide minerals in the concentrates. This rate was also found to increase with an increase in the chalcopyrite content in the concentrate, which indicated the presence of galvanic interactions between the minerals. At the same time, sphalerite and pyrrhotite, which are the minerals with a low rest potential, acted as dissolving anodes, while chalcopyrite and pyrite, having high rest potentials, were cathodes. The possibility of predicting the efficiency of zinc and iron removal during ferric leaching of the copper-zinc concentrates was shown in the context of sulfide mineral content.

Analysis of Waste Quality for Two-Step Biohydrometallurgical Processing of Copper–Zinc Concentrate

Iron and non-ferrous metals has been shown to accumulate in the liquid phase during the two-step biohydrometallurgical treatment of copper–zinc concentrate. The removal of iron as a precipitate from a solution obtained after ferric leaching of the concentrate and its subsequent bioregeneration has been studied. Iron was almost completely (98.3%) removed from the liquid phase as jarosite, and the pH value increased up to 2.4 with the addition of lime. About 95% of non-ferrous metals remained in the solution as sulfates. Comparative analysis of the obtained precipitates (including waste from the two-step process) showed that the loss of non-ferrous metals for them was lower than that in waste from the mining of copper–zinc ores and copper smelters.

Application of indirect non-contact bioleaching for extracting metals from waste lithium-ion batteries.

Applying biohydrometallurgy for metal extraction and recovery from mixed and polymetallic wastes such as electronic waste is limited due to microbial inhibition at low pulp densities and substrate (iron and sulfur) limitation. Here, we investigated the application of indirect non-contact bioleaching with biogenic ferric iron and sulfuric acid to extract metals from lithium-ion battery (LIB) waste. Results showed that although a single leach stage at ambient temperature only facilitated low leach yields (<10%), leach yields for all metals improved with multiple sequential leach stages (4 × 1 h). Biogenic ferric leaching augmented with 100 mM H2SO4 further enabled the highest leach yields (53.2% cobalt, 60.0% lithium, 48.7% nickel, 81.8% manganese, 74.4% copper). The proposed use of bioreagents is a viable and a more environmentally benign alternative to traditional mineral processing, which could be further improved by appropriate pre-treatment of the LIB waste.

Two-step biohydrometallurgical technology of copper-zinc concentrate processing as an opportunity to reduce negative impacts on the environment

Polymetallic concentrates obtained during ore beneficiation pose a significant problem for the mining and metallurgy industry due to an increase in load on subsequent comminution steps and a high loss of metals in slag during smelting. Storage of such slag can lead to pollution of groundwater due to weathering. Biohydrometallurgy is an option for the processing of sulfidic raw materials that has a low impact on the environment. Processing of sulfidic concentrates of copper-zinc ore via bioleaching techniques was studied in this paper. Three mixed microbial cultures of acidophilic microorganisms were enriched from industrial mining sites: two autotrophic mesophilic cultures containing Acidithiobacillus ferroxidans and Leptospirillum spp. (grown at 30 and 35 °C), and a mixotrophic moderate thermophilic culture containing Sulfobacillus thermotolerans, Leptospirillum ferriphilum, as well as the archaea Ferroplasma acidiphilum and Acidiplasma spp. (grown at 40 °C). The autotrophic microbial culture growing at 30 °C was used to generate an iron-containing biosolution for ferric leaching of a copper-zinc concentrate. Zinc and iron extracted into solution faster than copper during high-temperature (80 °C) ferric leaching of the concentrate due to galvanic interactions between minerals, redox conditions of the medium, and differences between mineral oxidation mechanisms. Weight loss of the leach residue was 34.0%, with relative copper content increased by 1.0%, zinc content decreased by 6.18%, and iron content decreased by 15.1%. Biooxidation of ferrous iron in the pregnant leach solution by three microbial cultures was also studied. The most effective culture was moderate thermophilic. The results of studies on the bioregeneration of leaching solutions are relevant to the development of a two-step biohydrometallurgical technology for processing of copper-zinc concentrate with a closed cycle of technological flows. The ferrous iron biooxidation rate by the moderate thermophilic culture reached 20 g L−1 day−1. The leach residue obtained can be considered a high-grade copper concentrate able to be processed via smelting. This bioleaching process would make it possible to reduce pollution of groundwater by some toxic metals stored in slags. An environmentally friendly technology flow sheet for copper-zinc sulfidic ore processing using two-step bioleaching treatment was proposed.