Method for gold extraction by stage potential control of thiosulfate
By employing a staged potential control method, the problem of high thiosulfate consumption in the thiosulfate process is solved, achieving high gold leaching rate, low consumption, and short leaching time. This method is applicable to various gold-containing materials, including quartz vein type, sulfide type, carbon-containing type, antimony-containing type, and gold-containing electronic waste.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CENT SOUTH UNIV
- Filing Date
- 2026-06-25
- Publication Date
- 2026-07-24
AI Technical Summary
In existing gold extraction technologies using the thiosulfate process, thiosulfate consumption is high, and existing potential control strategies fail to achieve a synergistic optimization of leaching rate and reagent consumption, resulting in a contradiction.
A staged potential control method was adopted, dividing the leaching process into initial, middle and late stages, and setting different target potential ranges (E1>E2>E3) for each stage. By switching the potential strategy through control means, the leaching rate and reagent consumption were synergistically optimized.
It significantly improves gold leaching rate, reduces thiosulfate consumption, shortens leaching time, is applicable to a variety of gold-containing materials, and is simple to implement and easy to industrialize.
Smart Images
Figure CN122445944A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a method for gold extraction from thiosulfate based on the active control of slurry potential in stages according to leaching time. Background Technology
[0002] The thiosulfate process is the most promising cyanide-free gold extraction technology for industrial application, boasting advantages such as being environmentally friendly, having a fast gold leaching rate, and good ore adaptability. However, this method has long faced the technical bottleneck of high thiosulfate consumption, severely restricting its industrial application. Thiosulfate consumption mainly comes from two aspects: firstly, consumption during the gold dissolution reaction (theoretical consumption), and secondly, decomposition consumption through catalytic oxidation by copper ions or mineral surfaces (additional consumption). Among these, additional consumption usually dominates and represents the main breakthrough point for reducing thiosulfate usage.
[0003] To address the high consumption of thiosulfate, scholars both domestically and internationally have conducted extensive research. Existing technologies can be mainly categorized into four types: self-generation of thiosulfate, construction of novel catalytic systems, use of additives, and control of reaction conditions. Among these, controlling reaction conditions is the most direct and commonly used technical approach.
[0004] Regarding the control of slurry potential in reaction condition regulation, existing technologies mainly include chemical reagent concentration control, electrochemical active control, and stepwise dosing control. While existing technologies have explored ways to reduce thiosulfate consumption from multiple perspectives, they share the following common problems in reaction condition regulation (especially potential control): thiosulfate leaching is treated as a homogeneous process, failing to recognize the differences in potential requirements at different leaching stages; potential control strategies are all "constant-state control" (maintaining a single potential throughout the process or a one-time initial adjustment), lacking the concept of "sequential scheduling"; and there is a contradiction between "reducing consumption" and "ensuring rate"—low potentials can reduce consumption but result in a slower leaching rate, while high potentials can increase the rate but increase consumption.
[0005] Therefore, it is necessary to find a method for gold extraction by staged potential regulation using thiosulfate to achieve synergistic optimization of leaching rate and reagent consumption. Summary of the Invention
[0006] This invention aims to overcome the technical problem that the constant potential control in the prior art cannot simultaneously take into account the leaching rate and reagent consumption, and provides a method for gold extraction by staged potential regulation of thiosulfate. According to the reaction characteristics of each stage of the leaching process, different target potential ranges (E1>E2>E3) are set in stages, and the potential control strategy is actively switched to achieve synergistic optimization of leaching rate and reagent consumption.
[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:
[0008] A method for staged potential-controlled gold extraction using thiosulfate comprises the following steps: (1) Mix the gold-bearing material with the gold thiosulfate leaching solution to form a slurry, and leach it. The leaching process is divided into three stages: the initial leaching stage, the middle leaching stage, and the later leaching stage. In the initial stage of leaching, the slurry potential is controlled in the first target potential range E1 by means of regulation, and maintained for time t1; this is the time period from the start of leaching to the leaching reaction entering the rapid dissolution stage. During the middle stage of leaching, the slurry potential is controlled in the second target potential range E2 through regulation methods and maintained for time t2; this is the time period from the rapid dissolution stage to the reaction entering a steady state. In the later stage of leaching, the slurry potential is controlled within the third target potential range E3 through regulation methods and maintained for time t3 until the leaching ends; this is the time period from when the reaction enters steady state to when the leaching ends. (2) After leaching, solid-liquid separation is performed to recover gold from the leachate; Among them, the first target potential range E1, the second target potential range E2 and the third target potential range E3 satisfy: E1>E2>E3, E3<+200 mV (ensuring that E3 is lower than the potential range of conventional low potential leaching), and E1, E2 and E3 are all measured relative to a standard hydrogen electrode; The holding time t1 in the initial stage of leaching is 0.5-3 h, the holding time t2 in the middle stage of leaching is 1-6 h, the holding time t3 in the later stage of leaching is 2-9 h, and the total leaching time is 6-12 h.
[0009] The principle and reaction mechanism of the staged potential-controlled gold extraction method of this invention are as follows: In gold leaching with thiosulfate, while high potentials can rapidly dissolve gold, they also violently decompose thiosulfate and generate a sulfoxyl passivation film, leading to leaching stagnation and low gold leaching rates. Low potentials, while inhibiting decomposition and passivation, result in insufficient overpotential for gold dissolution, resulting in slow leaching rates, long leaching times, and low gold leaching rates. This invention divides the leaching process into three stages, progressively decreasing the potential (E1>E2>E3): an initial high potential rapidly breaks down the passivation film and initiates gold dissolution; a medium potential in the middle stage balances rate and energy consumption; and a final low potential (below conventional low potential) actively inhibits the generation of sulfoxyl ions, keeping the gold surface clean. This avoids the passivation problem of continuous high potentials and overcomes the rate bottleneck of continuous low potentials, achieving a triple breakthrough of higher leaching rates, lower energy consumption, and shorter leaching times.
[0010] Furthermore, in the above method, the holding time t1 in the initial stage of leaching is 0.5-1.5 h, the holding time t2 in the middle stage of leaching is 2-4 h, the holding time t3 in the later stage of leaching is 3-7 h, and the total leaching time is 6-12 h.
[0011] Furthermore, the first target potential range E1 is +220 mV to +290 mV, the second target potential range E2 is +180 mV to +260 mV, and the third target potential range E3 is +120 mV to +190 mV, and the values of E1, E2, and E3 satisfy E1>E2>E3.
[0012] Furthermore, the thiosulfate leaching solution is obtained by sequentially adding ammonia, copper sulfate, and thiosulfate to water and mixing them; the initial concentration of thiosulfate in the thiosulfate leaching solution is 0.05-0.3 mol / L; and the pH value of the slurry is 8-12.
[0013] Furthermore, the thiosulfate is selected from one or more of sodium thiosulfate, calcium thiosulfate, and ammonium thiosulfate.
[0014] Furthermore, the gold-bearing material is selected from quartz vein-type gold mines, sulfide-type gold mines, carbon-bearing gold mines, antimony-bearing gold mines, or gold-bearing electronic waste.
[0015] Furthermore, when the gold-bearing material is a carbonaceous gold ore, an organic inhibitor is added in the early stage of leaching. The amount of the organic inhibitor added relative to the slurry is 0.1-5 g / t, and the organic inhibitor is selected from one or more of sodium humate, sodium carboxymethyl cellulose, and polyvinyl alcohol ammonium phosphate.
[0016] Furthermore, the method for recovering gold from the leachate is as follows: gold is recovered by electrodeposition to obtain elemental gold; or gold is adsorbed by ion exchange resin, then desorbed, and the desorbed solution is then electrodeposited or reduced to obtain elemental gold.
[0017] Furthermore, the control measures are selected from one or more of the following methods: (a) Adjust the type and flow rate of the gas introduced into the reactor, wherein the gas is selected from oxygen-enriched air, ordinary air or nitrogen; (b) Add a reducing agent; (c) Adjust the concentration of one or more reagents, including thiosulfate, copper ions, and ammonia; (d) Adjust the pH value of the slurry.
[0018] Furthermore, the reducing agent is selected from one or more of sodium sulfite, ascorbic acid, and thiourea.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention is the first to propose the concept of phased potential demand, which breaks through the traditional understanding of constant-state potential control. It introduces the time dimension into the potential control strategy and realizes the synergistic optimization of gold leaching rate and reagent consumption.
[0020] 2. The method of this invention achieves a dual breakthrough of higher gold leaching rate and lower reagent consumption. Compared with the high-potential method throughout the process, this invention significantly inhibits the decomposition of thiosulfate and the passivation of the gold surface by using a lower potential in the later stage, and the consumption of thiosulfate can be reduced by more than 30%, while the gold leaching rate is increased by 1-5%. Compared with the low-potential method throughout the process, this invention uses a higher potential in the early stage, which can increase the gold leaching rate by 5-15%, reduce the consumption of thiosulfate by more than 10%, and shorten the leaching time by 20-40%.
[0021] 3. The method of the present invention can determine the appropriate potential range through pre-experimentation based on the characteristics of different gold-containing materials, without changing the core control strategy (E1>E2>E3), and is applicable to a variety of gold-containing materials.
[0022] 4. The method of the present invention can be achieved simply by adjusting the ventilation rate and adding a reducing agent, which is simple to implement and does not require complex equipment such as electrode systems, power supplies, and feedback control, making it easy to promote industrially. Attached Figure Description
[0023] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a flowchart of the gold extraction process using thiosulfate staged potential regulation according to the present invention. Detailed Implementation
[0025] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.
[0026] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0027] 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.
[0028] In this invention, E1, E2, and E3 are all measured relative to a standard hydrogen electrode (SHE).
[0029] The gold extraction process of the thiosulfate staged potential-controlled extraction method of the present invention is as follows: Figure 1 As shown.
[0030] Example 1 (Quartz Vein Type Gold Deposit) A method for staged potential-controlled gold extraction using thiosulfate comprises the following steps: (1) Mix the gold-bearing material with thiosulfate leaching solution to form a slurry, and leach it. The leaching process is divided into three stages: the initial leaching stage, the middle leaching stage, and the later leaching stage. Gold-bearing materials: gold grade 5.2 g / t, the main minerals are quartz (75 wt.%) and hematite (5 wt.%). Gold leaching solution with thiosulfate: sodium thiosulfate 0.2 mol / L, CuSO4 0.02 mol / L, ammonia 1.5 mol / L; the pulp concentration after mixing is 40 wt.%. In the initial stage of leaching: the gold-bearing material and the gold thiosulfate leaching solution are added to the reactor to form a slurry (pH=11.0). The temperature is controlled at 25℃, stirring is started, and the stirring speed is 400 r / min (constant). The slurry potential is controlled within the range of E1 by adjustment methods and maintained for t1. Mid-stage leaching: When the leaching time reaches t1 or the pulp potential is monitored to naturally drop to the E2 range, switch the potential control method to control the pulp potential within the E2 range and maintain it for t2. Late stage of leaching: When the leaching time reaches t1+t2 or the pulp potential is detected to drop naturally to the range of E3, switch the potential control method again to control the pulp potential within the range of E3 for t3 until the leaching ends. The staged potential control in this embodiment (total leaching time 8 h) is shown in Table 1 below: Table 1: Staged Potential Control Table of the Invention
[0031] (2) After leaching, the slurry was filtered to obtain leaching solution and leaching residue. The gold grade of the leaching residue was analyzed after drying, and the leaching rate was calculated based on the difference in gold grade before and after leaching. Then, a strong basic anion exchange resin was added to the leaching solution for resin adsorption. The resin dosage was 20 g / L, and the adsorption time was 3 h. After adsorption, the gold-loaded resin and lean solution were obtained by filtration. The gold-loaded resin was desorbed using a mixed solution of sodium chloride and sodium sulfite. The sodium chloride concentration was 2 mol / L, the sodium sulfite concentration was 0.1 mol / L, the desorbent dosage was 10 resin bed volumes, and the desorbent flow rate was 2 resin bed volumes / h. After desorption, a gold-enriched desorbed solution was obtained. Gold was recovered by electrodeposition to obtain elemental gold products. The voltage was 2.0 V, and the deposition time was 3 h.
[0032] Experimental conditions for eight control groups: Control group 1: Low potential throughout (+160~+190 mV): Nitrogen gas was passed through at 0.2 L / min throughout the process, Na2SO3 was 0.3 g / L, and the leaching time was 12 h; Control group 2: High potential throughout (+230~+260 mV): Oxygen-enriched air was introduced at a rate of 0.4 L / min throughout the leaching process, with a leaching time of 6 h; Control group 3: Initial high potential (+230~+260 mV): oxygen-enriched air 0.4 L / min, leaching time 1 h; mid- and late-stage medium potential (+190~+220 mV): ordinary air 0.1 L / min, leaching time 7 h; Control group 4: Initial high potential (+230~+260 mV): oxygen-enriched air 0.4 L / min, leaching time 1 h; mid- and late-stage low potential (+130~+160 mV): nitrogen 0.2 L / min, Na2SO3 0.3 g / L, leaching time 8 h; Control group 5: Initial medium potential (+190~+220 mV): ordinary air 0.1 L / min, leaching time 3 h; middle and late low potential (+130~+160 mV): nitrogen 0.2 L / min, Na2SO3 0.3 g / L, leaching time 7 h; Control group 6: High potential in the initial and middle stages (+230~+260 mV): oxygen-enriched air 0.4 L / min, immersion time 3h; medium potential in the later stage (+190~+220 mV): ordinary air 0.1 L / min, immersion time 5h; Control group 7: High potential in the initial and middle stages (+230~+260 mV): oxygen-enriched air 0.4 L / min, leaching time 3h; low potential in the later stage (+130~+160 mV): nitrogen 0.2 L / min, Na2SO3 0.3 g / L, leaching time 6h; Control group 8: Initial and middle stage medium potential (+190~+220 mV): ordinary air 0.1 L / min, leaching time 4h; later stage low potential (+130~+160 mV): nitrogen 0.2 L / min, Na2SO3 0.3 g / L, leaching time 6h.
[0033] Gold leaching rate calculation method: The gold grade of the gold-containing raw material before and after leaching is detected by fire assay. The gold leaching rate is calculated based on the difference in quality and gold grade. Thiosulfate consumption rate: The concentration of thiosulfate in the solution before and after the reaction was determined by iodine titration, and the consumption rate was calculated based on the concentration difference.
[0034] Table 2: Comparison of results between this embodiment and other methods
[0035] The results are shown in Table 2. The present invention significantly improves the gold leaching rate and greatly reduces reagent consumption while shortening the leaching time. Moreover, the gold leaching rate, consumption rate and leaching time of the present invention are all superior to the schemes of low potential throughout the process, high potential throughout the process and two-stage potential adjustment.
[0036] Example 2 (Sulfide Gold Ore) A method for staged potential-controlled gold extraction using thiosulfate differs from Example 1 only in that: Gold-bearing materials: gold grade 28.3 g / t, arsenic content 8.5 wt.%, main minerals are arsenopyrite (15 wt.%) and pyrite (30 wt.%). The concentration of the mixed slurry is 25 wt.%; Initial leaching stage: Adjust the pulp pH to 11.0 and control the temperature at 35℃; The staged potential control in this embodiment (total leaching time 12 h) is shown in Table 3 below: Table 3: Staged Potential Control Table of the Invention
[0037] All other steps and parameters are exactly the same as in Example 1.
[0038] Experimental conditions for eight control groups: Control group 1: Low potential throughout (+180~+210 mV): Nitrogen gas was passed through at 0.3 L / min throughout the process, Na2SO3 was 0.5 g / L, and the leaching time was 16 h; Control group 2: High potential throughout (+250~+280 mV): Oxygen-enriched air was introduced at a rate of 0.8 L / min throughout the leaching process, with a leaching time of 8 h.
[0039] Control group 3: Initial high potential (+250~+280 mV): oxygen-enriched air 0.8 L / min, leaching time 1.5 h; Mid- and late-stage medium potential (+210~+240 mV): ordinary air 0.2 L / min, leaching time 10.5 h; Control group 4: Initial high potential (+250~+280 mV): oxygen-enriched air 0.8 L / min, leaching time 1.5 h; mid- and late-stage low potential (+150~+180 mV): nitrogen 0.3 L / min, Na2SO3 0.5 g / L, leaching time 11.5 h; Control group 5: Initial medium potential (+210~+240 mV): ordinary air 0.2 L / min, leaching time 3.5 h; middle and late low potential (+150~+180 mV): nitrogen 0.3 L / min, Na2SO3 0.5 g / L, leaching time 10.5 h; Control group 6: High potential in the initial and middle stages (+250~+280 mV): oxygen-enriched air 0.8 L / min, leaching time 5h; medium potential in the later stage (+210~+240 mV): ordinary air 0.2 L / min, leaching time 7h; Control group 7: High potential in the initial and middle stages (+250~+280 mV): oxygen-enriched air 0.8 L / min, leaching time 4h; low potential in the later stage (+150~+180 mV): nitrogen 0.3 L / min, Na2SO3 0.5 g / L, leaching time 9h; Control group 8: Initial and middle stage medium potential (+210~+240 mV): ordinary air 0.2 L / min, leaching time 5h; later stage low potential (+150~+180 mV): nitrogen 0.3 L / min, Na2SO3 0.5 g / L, leaching time 9h.
[0040] The test conditions were the same as in Example 1.
[0041] Table 4: Comparison of results between this embodiment and other methods
[0042] The results are shown in Table 4. The gold leaching rate, consumption rate and leaching time of the present invention are all superior to the schemes of low potential throughout the process, high potential throughout the process and two-stage adjustment potential.
[0043] Example 3 (Carbon-bearing gold ore) A method for staged potential-controlled gold extraction using thiosulfate differs from Example 1 only in that: Gold-bearing material: gold grade 4.2 g / t, organic carbon content 1.2 wt.%; Initial leaching stage: Adjust the pulp pH to 10.0 and add 2 g / t of sodium humate; The staged potential control in this embodiment (total leaching time 10 h) is shown in Table 5 below: Table 5: Staged Potential Control Table of the Invention
[0044] All other steps and parameters are exactly the same as in Example 1.
[0045] Experimental conditions for two control groups: Control group 1: Low potential throughout (+180~+210 mV): Nitrogen gas was passed through at 0.3 L / min throughout the process, Na2SO3 was 0.4 g / L, and the leaching time was 14 h; Control group 2: High potential throughout (+250~+280 mV): Oxygen-enriched air was introduced at a rate of 0.5 L / min throughout the leaching process, with a leaching time of 7 h.
[0046] The test conditions were the same as in Example 1.
[0047] Table 6: Comparison of results between this embodiment and other methods
[0048] The results are shown in Table 6. The gold leaching rate, consumption rate and leaching time of the present invention are all better than the schemes with low potential throughout and high potential throughout.
[0049] Example 4 (Antimony-Gold Ore) A method for staged potential-controlled gold extraction using thiosulfate differs from Example 1 only in that: Gold-bearing materials: gold grade 42.5 g / t, antimony content 6.2 wt.%, main mineral stibnite (12 wt.%). The concentration of the mixed slurry is 20 wt.%; Initial leaching stage: Adjust the pulp pH to 11.2 and control the temperature at 40℃; The staged potential control in this embodiment (total leaching time 12 h) is shown in Table 7 below: Table 7: Staged Potential Control Table of the Invention
[0050] All other steps and parameters are exactly the same as in Example 1.
[0051] Experimental conditions for two control groups: Control group 1: Low potential throughout (+190~+220 mV): Nitrogen gas was passed through at 0.4 L / min throughout the process, Na2SO3 was 0.8 g / L, and the leaching time was 18 h; Control group 2: High potential throughout (+260~+290 mV): Oxygen-enriched air was introduced at a rate of 1.0 L / min throughout the leaching process, with a leaching time of 8 h.
[0052] The test conditions were the same as in Example 1.
[0053] Table 8: Comparison of results between this embodiment and other methods
[0054] The results are shown in Table 8. The gold leaching rate, consumption rate and leaching time of the present invention are all better than the schemes with low potential throughout and high potential throughout.
[0055] Example 5 (Gold-containing electronic waste) A method for staged potential-controlled gold extraction using thiosulfate differs from Example 1 only in that: Gold-containing material: gold grade 280 g / t, copper 15 wt.%, tin 3 wt.%, after crushing and roasting at 300℃ to remove organic matter; Gold leaching solution with thiosulfate: sodium thiosulfate 0.2 mol / L, ammonia 1.0 mol / L (Cu is dissolved by the material itself); the slurry concentration after mixing is 20 wt.%. Initial leaching stage: Adjust the pulp pH to 10.8 and control the temperature at 40℃; The staged potential control in this embodiment (total leaching time 7 h) is shown in Table 9 below: Table 9: Staged Potential Control Table of the Invention
[0056] All other steps and parameters are exactly the same as in Example 1.
[0057] Experimental conditions for two control groups: Control group 1: Low potential throughout (+150~+180 mV): Nitrogen gas was passed through at 0.3 L / min throughout the process, Na2SO3 was 0.5 g / L, and the leaching time was 10 h; Control group 2: High potential throughout (+220~+250 mV): Oxygen-enriched air was introduced at a rate of 0.6 L / min throughout the leaching process, with a leaching time of 5 h.
[0058] The test conditions were the same as in Example 1.
[0059] Table 10: Comparison of results between this embodiment and other methods
[0060] The results are shown in Table 10. The gold leaching rate, consumption rate and leaching time of the present invention are all better than the schemes with low potential throughout and high potential throughout.
[0061] Example 6 (Quartz Vein Type Gold Deposit) A method for staged potential-controlled gold extraction using thiosulfate is the same as that in Example 1 in terms of operation steps and raw materials. The difference lies in the means of controlling the potential. In Example 1, the potential is controlled by gas and reducing agent, while in this example, the potential is controlled by adjusting the concentration of a small amount of reagent (including reducing agent, which can affect pH).
[0062] The staged potential control in this embodiment (total leaching time 8 h) is shown in Table 11 below: Table 11: Staged Potential Control Table of the Invention
[0063] Experimental conditions for two control groups: Control group 1: High potential throughout (+220~+240 mV): Sodium thiosulfate 0.2 mol / L, CuSO4 0.02 mol / L, ammonia 1.5 mol / L, initial slurry pH=11.0, sodium thiosulfate, CuSO4 and ammonia were added every half hour to restore the concentration and slurry pH to the initial values, leaching time 6 h; Control group 2: Low potential throughout (150+~+170 mV): Sodium thiosulfate 0.05 mol / L, CuSO4 0.002 mol / L, ammonia 0.5 mol / L, initial slurry pH=10.0, sodium thiosulfate, CuSO4 and ammonia were added every half hour to restore the concentration and pH of the slurry to the initial values, leaching time 12 h.
[0064] All other steps and parameters are exactly the same as in Example 1.
[0065] Table 12: Comparison of results between this embodiment and other methods
[0066] The results are shown in Table 12. By slightly adjusting the concentration of the reagent to affect the pH of the slurry, the present invention also significantly improves the gold leaching rate and greatly reduces the reagent consumption while shortening the leaching time. Moreover, the gold leaching rate, consumption rate and leaching time of the present invention are all superior to the schemes of low potential throughout the process, high potential throughout the process and two-stage potential adjustment.
[0067] In summary, this invention overcomes the limitations of existing constant-state potential control technology by actively regulating the slurry potential in stages, achieving synergistic optimization of gold leaching rate and thiosulfate consumption. It boasts significant advantages such as high leaching rate, low reagent consumption, short leaching time, wide applicability, and ease of industrialization. The above descriptions are merely preferred embodiments of this invention and are not intended to limit the invention. Those skilled in the art can make various improvements and modifications without departing from the technical principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.
Claims
1. A method for staged potential-controlled gold extraction using thiosulfate, characterized in that, Includes the following steps: (1) Mix the gold-bearing material with thiosulfate leaching solution to form a slurry, and leach it. The leaching process is divided into three stages: the initial leaching stage, the middle leaching stage, and the later leaching stage. In the initial stage of leaching, the slurry potential is controlled in the first target potential range E1 by means of regulation, and maintained for time t1. During the middle stage of leaching, the slurry potential is controlled in the second target potential range E2 by means of regulation, and maintained for time t2. In the later stage of leaching, the slurry potential is controlled at the third target potential range E3 by means of regulation and control, and maintained for time t3 until the leaching is completed; (2) After leaching, solid-liquid separation is performed to recover gold from the leachate; The first target potential range E1, the second target potential range E2, and the third target potential range E3 satisfy the following conditions: E1>E2>E3, E3<+200 mV, and E1, E2, and E3 are all measured relative to a standard hydrogen electrode. The holding time t1 in the initial stage of leaching is 0.5-3 h, the holding time t2 in the middle stage of leaching is 1-6 h, the holding time t3 in the later stage of leaching is 2-9 h, and the total leaching time is 6-12 h.
2. The method according to claim 1, characterized in that, The holding time t1 in the initial stage of leaching is 0.5-1.5 h, the holding time t2 in the middle stage of leaching is 2-4 h, the holding time t3 in the later stage of leaching is 3-7 h, and the total leaching time is 6-12 h.
3. The method according to claim 1, characterized in that, The first target potential range E1 is +220 mV to +290 mV, the second target potential range E2 is +180 mV to +260 mV, and the third target potential range E3 is +120 mV to +190 mV, and the values of E1, E2, and E3 satisfy E1>E2>E3.
4. The method according to claim 1, characterized in that, The thiosulfate leaching solution is obtained by sequentially adding ammonia, copper sulfate, and thiosulfate to water and mixing them together; the initial concentration of thiosulfate in the thiosulfate leaching solution is 0.05-0.3 mol / L; and the pH value of the slurry is 8-12.
5. The method according to claim 4, characterized in that, The thiosulfate is selected from one or more of sodium thiosulfate, calcium thiosulfate, and ammonium thiosulfate.
6. The method according to claim 1, characterized in that, The gold-bearing materials are selected from quartz vein-type gold mines, sulfide-type gold mines, carbon-bearing gold mines, antimony-bearing gold mines, or gold-bearing electronic waste.
7. The method according to claim 6, characterized in that, When the gold-bearing material is a carbonaceous gold ore, an organic inhibitor is added in the early stage of leaching. The amount of the organic inhibitor added relative to the slurry is 0.1-5 g / t. The organic inhibitor is selected from one or more of sodium humate, sodium carboxymethyl cellulose, and polyvinyl alcohol ammonium phosphate.
8. The method according to claim 1, characterized in that, The method for recovering gold from the leachate is as follows: gold is recovered by electrodeposition to obtain elemental gold; or gold is adsorbed by ion exchange resin, then desorbed, and the desorbed solution is then electrodeposited or reduced to obtain elemental gold.
9. The method according to claim 1, characterized in that, The control measures are selected from one or more of the following methods: (a) Adjust the type and flow rate of the gas introduced into the reactor, wherein the gas is selected from oxygen-enriched air, ordinary air or nitrogen; (b) Add a reducing agent; (c) Adjust the concentration of one or more reagents, including thiosulfate, copper ions, and ammonia; (d) Adjust the pH value of the slurry.
10. The method according to claim 9, characterized in that, The reducing agent is selected from one or more of sodium sulfite, ascorbic acid, and thiourea.