A method for bioleaching of copper and zinc from lead-zinc smelting slag
By using microbial technology to leach copper and zinc from lead-zinc smelting slag under mild conditions with acidophilic leaching bacteria, the problems of high energy consumption and high pollution in traditional metallurgical technology have been solved, and efficient recovery and low-cost production of copper and zinc have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHWEST NORMAL UNIVERSITY
- Filing Date
- 2026-01-23
- Publication Date
- 2026-06-05
AI Technical Summary
Traditional pyrometallurgical and hydrometallurgical techniques suffer from high energy consumption, high pollution, and low efficiency when processing lead-zinc smelting slag, especially in terms of low recovery efficiency of low-grade valuable metals, and there is insufficient research on bioleaching.
Microbial technology was employed to leach lead-zinc smelting slag in an acidic culture medium using acidophilic leaching bacteria acclimated to metal salt stress. Under mild conditions, a mixture of bacteria, including acidophilic thiobacillus and acidophilic ferrothiobacillus, converted copper and zinc from the solid phase into soluble ions.
It achieves efficient and green recycling of copper and zinc, reduces production costs and harmful gas emissions, conforms to the concept of sustainable development, and has low material consumption.
Smart Images
Figure CN122147067A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solid waste recycling, specifically relating to a method for the bioleaching of copper and zinc from lead-zinc smelting slag. Background Technology
[0002] Lead-zinc mining and smelting processes generate massive amounts of smelting slag. This waste not only occupies a large amount of land resources but also poses a serious environmental threat by causing heavy metal pollution to surrounding soil and water bodies. However, this lead-zinc smelting slag is not entirely waste; it often contains a certain amount of valuable metals, such as copper (approximately 0.4-0.6%) and zinc (approximately 3-6%). These valuable metals are strategic metals, and their demand and value are increasing daily.
[0003] Traditional pyrometallurgical and hydrometallurgical technologies for treating lead-zinc smelting slag are often accompanied by high energy consumption and high pollution (such as SO2). x The bioleaching process for lead-zinc smelting slag presents challenges such as emissions and acidic wastewater, and its recovery efficiency for low-grade valuable metals is low. Current research on bioleaching for lead-zinc smelting slag is lacking. Summary of the Invention
[0004] The purpose of this invention is to utilize microbial technology to convert the copper and zinc residues in lead-zinc smelting slag from the solid phase into soluble ions under mild conditions, thereby achieving green and efficient recovery of copper and zinc.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A bioleaching method for copper and zinc in lead-zinc smelting slag is characterized by: adding the lead-zinc smelting slag to an acidic culture medium inoculated with acidophilic leaching bacteria acclimated under metal salt stress for a certain period of time for leaching reaction.
[0006] Preferably, the acidophilic leaching bacteria are selected from at least one of the following: acidophilic thiobacillus, acidophilic ferro-thiobacillus, sulfur-oxidizing thiobacillus, thermophilic acidophilic thiobacillus, and 10,000 acidophilic bacteria.
[0007] More preferably, the acidophilic leaching bacteria is a mixed species composed of *Thiobacillus acidophilus*, *Thiobacillus acidophilus*, and *Thiobacillus thermophilus*.
[0008] Preferably, the step of acclimating the acidophilic leaching bacteria to metal salt stress includes: Inoculate the culture medium with acidophilic leaching bacteria and add an iron-sulfur source; Then, metal salts are added to the culture medium in batches to increase the concentration gradient of the metal salts. After each addition of metal salts, the culture is carried out for a period of time until the strain grows stably. The metal salts are a combination of magnesium salts, aluminum salts, iron salts, zinc salts and copper salts.
[0009] More preferably, the final concentrations of the magnesium salt, aluminum salt, iron salt, zinc salt, and copper salt are as follows: Mg 2+ 5-10 g / L, Al 3+ 5-10 g / L, Fe 3+ 8-10 g / L, Zn 2+ 5-10 g / L, Cu 2+ 5-10 g / L.
[0010] More preferably, the iron-sulfur source is selected from at least one of elemental sulfur, pyrite, chalcopyrite, arsenopyrite, lead-zinc ore, and bainite.
[0011] More preferably, the iron-sulfur source is added to the culture medium at a concentration of 5-7 g / L.
[0012] More preferably, the culture medium is a solution containing 2 g / L (NH4)2SO4, 0.4 g / L KCl, 0.5 g / L KH2PO4, and 0.4 g / L MgSO4·7H2O.
[0013] Preferably, the acidic culture medium is a solution with a pH value of 0.5-3 containing 2 g / L (NH4)2SO4, 0.4 g / L KCl, 0.5 g / L KH2PO4, and 0.4 g / L MgSO4·7H2O.
[0014] More preferably, the pH value of the acidic culture medium is 1 to 2.
[0015] Preferably, the initial concentration of the lead-zinc smelting slag in the leaching reaction system is 10-40 g / L, the reaction temperature is 25-45℃, and the reaction time is 5-9 days.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention utilizes acidophilic leaching bacteria acclimated under high concentration of metal salt stress to achieve efficient leaching of copper and zinc from lead-zinc smelting slag, turning waste into treasure and transforming the original environmental burden into valuable resources, which is in line with the concepts of sustainable development and circular economy.
[0017] 2. The bioleaching process of this invention is carried out under mild conditions and has low material consumption, which can significantly reduce production costs.
[0018] 3. Compared with traditional pyrometallurgical and hydrometallurgical processes, this invention reduces SO2 and NO content. x It has extremely low emissions of harmful gases and generates little wastewater that is easy to treat, making it an environmentally friendly method for metal extraction. Attached Figure Description
[0019] Figure 1This is a backscattered electron image (BSE) of a cross-section of lead-zinc smelting slag particles before bioleaching.
[0020] Figure 2 Field emission electron probe microanalysis (EPMA) image of elemental distribution in cross-section of lead-zinc smelting slag particles before bioleaching.
[0021] Figure 3 Example 4: Changes in copper and zinc leaching rates over time in lead-zinc smelting slag.
[0022] Figure 4 This is a backscattered image of the lead-zinc smelting slag residue after 7 days of bioleaching in Example 4.
[0023] Figure 5 This is a field emission electron probe microanalysis image of the elemental distribution of lead-zinc smelting slag residue 7 days after bioleaching in Example 4. Detailed Implementation
[0024] The technical solution of the present invention will be further described in detail below with reference to the embodiments.
[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.
[0026] The composition of Simplified Inorganic Salt Culture Medium (SSM) is: (NH4)2SO4 2 g / L, KCl 0.4 g / L, KH2PO4 0.5 g / L, MgSO4·7H2O 0.4 g / L, with the remainder being water.
[0027] Acidophilic leaching bacteria: Acidophilic thiobacillus (Thiobacillus acidophilus) Acidithiobacillus thiooxidans ), Acidophilic ferrous thiobacillus ( Acidithiobacillus ferrooxidans ), sulfur-oxidizing sulfobacillus ( Sulfobacillus thermosu lfidooxidans ), thermophilic acidophilic thiobacillus ( Acidithiobacillus caldus ), Wanzao acidophilus ( Acidianus manzaensis ).
[0028] Domestication of acidophilic leaching bacteria: First, inoculate the bacteria into SSM (sulfur-rich soil medium), then add an iron-sulfur source as an energy source for bacterial growth. Next, add metal salts in batches to gradually increase the concentration of metal salts in the culture medium until the desired high concentration (Mg) is reached. 2+ 5-10 g / L, Al 3+ 5-10 g / L, Fe 3+ 8-10 g / L, Zn 2+ 5-10 g / L, Cu 2+ (5-10 g / L). After each increase in concentration, culture for a period of time until the strain can grow stably. Finally, a domesticated strain that can tolerate high concentrations of metal salt stress is obtained.
[0029] The specific acclimatization conditions for the acidophilic leaching bacteria in each embodiment of the present invention are as follows: the inoculum concentration is 1×10⁻⁶. 8 cells / mL; the iron-sulfur source was arsenopyrite at a concentration of 6 g / L; the metal salt was a mixture of MgSO4, Al2(SO4)3, Fe2(SO4)3, ZnSO4, and CuSO4, administered according to Mg... 2+ Al 3+ Fe 3+ Zn 2+ Cu 2+ The concentration of each component was increased by 2 g / L until the acidophilic leaching bacteria could finally adapt to 10 g / L Mg. 2+ 10 g / L Al 3+ 10 g / L Fe 3+ 10 g / L Zn 2+ 10 g / L Cu 2+ An environment of coexistence.
[0030] The lead-zinc smelting slag was provided by Baiyin Nonferrous Honglu Resource Comprehensive Utilization Technology Co., Ltd. The slag is the water-quenched slag after lead and zinc are recovered by reduction and volatilization in the fuming furnace during the closed blast furnace zinc smelting (ISP) process. Analysis confirmed that its copper (Cu) content is about 0.4-0.6% and its zinc (Zn) content is about 3.5-5.2%.
[0031] Pretreatment of lead-zinc smelting slag in various embodiments of the present invention: crushing and grinding to reduce the particle size to less than 74 μm (200 mesh).
[0032] In the various embodiments of the present invention, a 500 mL Erlenmeyer flask is used as the reaction vessel for bioleaching.
[0033] Example 1 (1) After sterilization, SSM is poured into the reaction vessel, controlling the liquid volume to occupy 1 / 3 of the total volume of the reaction vessel. Then, the pH of the SSM is adjusted to 2.0 with 1 mol / L sulfuric acid. Then, a solution with a concentration of 6 × 10⁻⁶ is added. 7 Inoculate with acclimatized *Thiobacillus acidophilus* cells / mL. Acidithiobacillus ferrooxidans Finally, lead-zinc smelting slag is added at a slurry concentration of 20 g / L.
[0034] (2) The reaction vessel was placed in a constant temperature shaker, and the reaction temperature was set to 30 °C and the rotation speed to 180 rpm. During the leaching reaction, the leachate was taken every 24 h, filtered, centrifuged at high speed, and diluted. The concentrations of copper and zinc were then detected by inductively coupled plasma optical emission spectrometry (ICP-OES). After 7 days of bioleaching reaction, the leaching rates of copper and zinc in the lead-zinc smelting slag were 70.6% and 88.1%, respectively.
[0035] Example 2 The operation was the same as in Example 1, except that the pH of the SSM was adjusted to 1.0. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in the lead-zinc smelting slag were 83.9% and 91.4%, respectively.
[0036] Example 3 The procedure was the same as in Example 1, except that the pH of the SSM was adjusted to 3.0. After 7 days of bioleaching, the leaching rates of copper and zinc in the lead-zinc smelting slag were 51.2% and 72.6%, respectively.
[0037] Example 4 (1) After sterilization, SSM is poured into the reaction vessel, controlling the liquid volume to occupy 1 / 3 of the total volume of the reaction vessel. Then, the pH of the SSM is adjusted to 1.0 with 1 mol / L sulfuric acid. Then, a solution of 6 × 10⁻⁶ mol / L is added. 7 Inoculate with well-acclimated *Thiobacillus acidophilus* at a concentration of cells / mL. Acidithiobacillus thiooxidans ), Acidophilic ferrous thiobacillus ( Acidithiobacillus ferrooxidans ) and thermophilic acidophilic thiobacillus ( Acidithiobacillus caldus A mixed bacterial strain with a cell ratio of 2:1:1 was added to the lead-zinc smelting slag at a slurry concentration of 20 g / L.
[0038] (2) The reaction vessel was placed in a constant temperature shaker, and the reaction temperature was set to 35 ℃ and the rotation speed was 180 rpm. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in lead-zinc smelting slag were 91.3% and 97.8%, respectively.
[0039] Backscattering plot and elemental distribution of lead-zinc smelting slag before bioleaching reaction are as follows: Figure 1 and Figure 2 As shown. The backscattering plot and elemental distribution of the residue after 7 days of bioleaching are shown in the figure. Figure 4 and Figure 5 As shown.
[0040] like Figure 3 As shown, the leaching rate of copper and zinc gradually increases with the increase of the leaching reaction days, and tends to stabilize after 6 days.
[0041] Example 5 The operation process was the same as in Example 4, except that the temperature of the bioleaching reaction was set to 30 °C. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in the lead-zinc smelting slag were 88.9% and 93.5%, respectively.
[0042] Example 6 (1) After sterilization, SSM is poured into the reaction vessel, controlling the liquid volume to occupy 1 / 3 of the total volume of the reaction vessel. Then, the pH of the SSM is adjusted to 1.0 with 1 mol / L sulfuric acid. Then, a solution with a concentration of 6 × 10⁻⁶ is added. 7Inoculate with acclimatized acidophilic thiobacillus (cells / mL) Acidithiobacillus thiooxidans Finally, lead-zinc smelting slag is added at a slurry concentration of 20 g / L.
[0043] (2) Place the reaction vessel in a constant temperature shaker, set the reaction temperature to 30 ℃ and the rotation speed to 180 rpm. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in lead-zinc smelting slag were 81.5% and 90.2%, respectively.
[0044] Example 7 (1) After sterilization, SSM is poured into the reaction vessel, controlling the liquid volume to occupy 1 / 3 of the total volume of the reaction vessel. Then, the pH of the SSM is adjusted to 1.0 with 1 mol / L sulfuric acid. Then, a solution with a concentration of 6 × 10⁻⁶ is added. 7 Inoculate with acclimatized thermophilic acidophilic thiobacillus (cells / mL) Acidithiobacillus caldus Finally, lead-zinc smelting slag is added at a slurry concentration of 20 g / L.
[0045] (2) The reaction vessel was placed in a constant temperature shaker, and the reaction temperature was set to 30 °C and the rotation speed was 180 rpm. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in lead-zinc smelting slag were 73.8% and 88.9%, respectively.
[0046] Example 8 The operation process was the same as in Example 4, except that the pH of the SSM was adjusted to 2.0 and the bioleaching reaction temperature was set to 30 °C. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in the lead-zinc smelting slag were 73.1% and 86.7%, respectively.
[0047] Example 9 The operation process was the same as in Example 4, except that the lead-zinc smelting slag was added at a slurry concentration of 40 g / L, and the bioleaching reaction temperature was set at 30 °C. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in the lead-zinc smelting slag were 72.8% and 89.1%, respectively.
[0048] Example 10 The operation process was the same as in Example 4, except that lead-zinc smelting slag was added at a slurry concentration of 40 g / L, and the bioleaching reaction temperature was set at 25 °C. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in the lead-zinc smelting slag were 81.7% and 91.6%, respectively.
[0049] Example 11 (1) After sterilization, SSM is poured into the reaction vessel, controlling the liquid volume to occupy 1 / 3 of the total volume of the reaction vessel. Then, the pH of the SSM is adjusted to 3.0 with 1 mol / L sulfuric acid. Then, a solution with a concentration of 6 × 10⁻⁶ is added. 7 Inoculate with acclimatized acidophilic thiobacillus (cells / mL)Acidithiobacillus thiooxidans Finally, lead-zinc smelting slag is added at a slurry concentration of 20 g / L.
[0050] (2) The reaction vessel was placed in a constant temperature shaker, and the reaction temperature was set to 30 ℃ and the rotation speed was 180 rpm. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in lead-zinc smelting slag were 58.5% and 76.9%, respectively.
[0051] Comparative Example 1 (1) After sterilization, SSM is poured into the reaction vessel, controlling the liquid volume to occupy 1 / 3 of the total volume of the reaction vessel. Then, the pH of the SSM is adjusted to 1.0 with 1 mol / L sulfuric acid. Then, a solution of 6 × 10⁻⁶ mol / L is added. 7 Inoculated with *Thiobacillus acidophilus* at a concentration of cells / mL. Acidithiobacillus thiooxidans ), Acidophilic ferrous thiobacillus ( Acidithiobacillus ferrooxidans ) and thermophilic acidophilic thiobacillus ( Acidithiobacillus caldus A mixed bacterial strain (unacclimated to metal salt stress) with a cell number ratio of 2:1:1 was added to lead-zinc smelting slag at a slurry concentration of 20 g / L.
[0052] (2) The reaction vessel was placed in a constant temperature shaker, and the reaction temperature was set to 35 ℃ and the rotation speed was 180 rpm. After 7 days of bioleaching reaction, the leaching rates of copper and zinc in lead-zinc smelting slag were 71.2% and 80.1%, respectively.
[0053] Comparative Example 2 (1) After sterilization, SSM is poured into the reaction vessel, and the liquid volume is controlled to be 1 / 3 of the total volume of the reaction vessel. Then, the pH of SSM is adjusted to 1.0 with 1 mol / L sulfuric acid, and then lead-zinc smelting slag is added with a slurry concentration of 20 g / L.
[0054] (2) The reaction vessel was placed in a constant temperature shaker, and the reaction temperature was set to 35 ℃ and the rotation speed was 180 rpm. After 7 days of leaching, the leaching rates of copper and zinc in the lead-zinc smelting slag were 12.6% and 39.8%, respectively.
[0055] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for bioleaching copper and zinc from lead-zinc smelting slag, characterized in that: This involves adding lead-zinc smelting slag to an acidic culture medium inoculated with acidophilic leaching bacteria acclimated to metal salt stress, and leaching for a certain period of time.
2. The method according to claim 1, characterized in that: The acidophilic leaching bacteria are selected from at least one of the following: acidophilic thiobacillus, acidophilic ferro-thiobacillus, sulfur-oxidizing thiobacillus, thermophilic acidophilic thiobacillus, and 10,000 acidophilic bacteria.
3. The method according to claim 2, characterized in that: The acidophilic leaching bacteria are a mixed species composed of acidophilic thiobacillus, acidophilic ferro-thiobacillus, and thermophilic acidophilic thiobacillus.
4. The method according to claim 1, characterized in that: The steps for acclimating the acidophilic leaching bacteria to metal salt stress include: Inoculate the culture medium with acidophilic leaching bacteria and add an iron-sulfur source; Then, metal salts are added to the culture medium in batches to increase the concentration gradient of the metal salts. After each addition of metal salts, the culture is carried out for a period of time until the strain grows stably. The metal salts are a combination of magnesium salts, aluminum salts, iron salts, zinc salts and copper salts.
5. The method according to claim 4, characterized in that: The final concentrations of the magnesium, aluminum, iron, zinc, and copper salts are as follows: Mg 2+ 5-10 g / L, Al 3+ 5-10 g / L, Fe 3+ 8-10 g / L, Zn 2+ 5-10 g / L, Cu 2+ 5-10 g / L.
6. The method according to claim 4, characterized in that: The iron-sulfur source is selected from at least one of elemental sulfur, pyrite, chalcopyrite, arsenopyrite, lead-zinc ore, and chalcopyrite; preferably, the iron-sulfur source is added to the culture medium at a concentration of 5-7 g / L.
7. The method according to claim 4, characterized in that: The culture medium is a solution containing 2 g / L (NH4)2SO4, 0.4 g / L KCl, 0.5 g / L KH2PO4, and 0.4 g / L MgSO4·7H2O.
8. The method according to claim 1, characterized in that: The acidic culture medium is a solution with a pH value of 0.5-3 containing 2 g / L (NH4)2SO4, 0.4 g / L KCl, 0.5 g / L KH2PO4, and 0.4 g / L MgSO4·7H2O; preferably, the pH value is 1-2.
9. The method according to claim 1, characterized in that: The initial concentration of the lead-zinc smelting slag in the leaching reaction system is 10-40 g / L, the reaction temperature is 25-45℃, and the reaction time is 5-9 days.
10. The method according to claim 1, characterized in that: The copper content of the lead-zinc smelting slag is 0.4-0.6%, and the zinc content is 3-6%.