A method for separating copper and germanium from a zinc hydrometallurgy leach solution

Abstract

The application discloses a method for separating copper and germanium from a zinc hydrometallurgy leaching solution, and belongs to the technical field of metallurgical chemical industry. The method comprises the following steps: adding the zinc hydrometallurgy leaching solution containing copper and germanium into a sealed reaction kettle, adding crystal seeds into the solution, and then adding hydrogen sulfide gas; under the conditions of 70-90 DEG C and 0.1-0.3 MPa, the solution is stirred for 5-30 min; after the reaction is completed, the copper precipitation solid product is obtained through filtration, and the germanium does not precipitate and remains in the copper precipitation solution; the copper precipitation solution is neutralized to pH 2-3 by using a neutralizing agent; after liquid-solid separation, the obtained neutralized solution is added with a germanium precipitation agent to precipitate germanium at 70-85 DEG C; after liquid-solid separation, the germanium-rich residue is obtained. The method realizes the separation of copper and germanium through the above-mentioned step-by-step selective precipitation mode, and has the advantages of high separation efficiency, fast reaction rate, cleanness and high efficiency.

Description

Technical Field

[0001] This invention relates to a method for separating copper and germanium from wet zinc smelting leachate, belonging to the field of metallurgical and chemical technology. Background Technology

[0002] In nature, germanium rarely forms independent minerals; it primarily exists as an isomorphous inclusion in the sphalerite crystal lattice. Consequently, zinc concentrates from some producing areas contain 50–500 g / t of germanium. Additionally, zinc concentrates from other producing areas contain 0.3–2% copper. In actual hydrometallurgical zinc refining processes, when processing zinc sulfide concentrates containing germanium and copper, neutral leaching, low-acid leaching, and reductive leaching produce copper- and germanium-containing hydrometallurgical zinc leaching solutions. These solutions typically contain 0.5–2 g / L copper ions, 20–150 mg / L germanium ions, and 5–40 g / L of free sulfuric acid and a certain concentration of ferric ions. Traditional methods such as iron powder replacement and tannin precipitation suffer from low separation efficiency due to the influence of impurity ions and free sulfuric acid in the solution, leading to co-precipitation of copper and germanium. Patent application number 202510802297.1 proposes a method for selectively precipitating copper by substituting iron powder with copper to obtain sponge copper. Approximately 5% or less of germanium enters the sponge copper. However, excessive iron powder addition increases germanium precipitation loss, and fluctuations in solution chemical composition during production lead to poor process control stability. Patent application number 20220003289.7 discloses a method for separating copper and germanium in a hydrometallurgical zinc smelting process. This method involves mixing copper-germanium-zinc roasted ore with water or wash water to form a slurry. The mixed slurry is then mixed with a zinc sulfate solution from the hydrometallurgical zinc smelting process and an oxidant. A weak acid leaching process is used to precipitate copper and ferric germanium. The weak acid solution is then used for copper recovery using zinc powder or iron powder displacement precipitation technology, yielding copper-rich slag. Existing methods for separating copper and germanium from hydrometallurgical zinc solutions have certain advantages, but they also suffer from technical challenges such as easy co-precipitation of copper and germanium, low separation degree, complex processes, and difficulty in process control. Therefore, researching novel germanium precipitants and stepwise selective precipitation processes for enriching copper and germanium has become the technological development direction in this field. Summary of the Invention

[0003] To overcome the problems and shortcomings of the prior art, this invention provides a method for separating copper and germanium from wet zinc smelting leaching solutions. This invention employs a stepwise selective precipitation method to achieve copper-germanium separation. First, copper is selectively precipitated in an acidic solution using seed-induced precipitation and selective sulfide precipitation, yielding copper-rich slag; germanium remains in the post-precipitation solution without precipitation. Simultaneously, air is used as a pressure-maintaining medium to increase the solubility of hydrogen sulfide in the solution, improving the copper precipitation efficiency. The post-precipitation solution is neutralized to a pH of 2-3 with a neutralizing agent, filtered, and then a germanium-precipitating agent is added to the resulting neutralized solution to precipitate germanium, obtaining germanium-rich slag.

[0004] To achieve the above objectives, the present invention provides a method for separating copper and germanium from a wet zinc smelting leaching solution, comprising:

[0005] A wet zinc leaching solution containing copper and germanium is added to a closed reactor. Seed crystals are added to the solution, followed by hydrogen sulfide gas. The reaction is carried out at 70-95°C and 0.1-0.3 MPa with stirring for at least 5 minutes. After the reaction, the mixture is filtered to obtain a copper-precipitated solid product. Germanium does not precipitate and remains in the copper-precipitated liquid. The copper-precipitated liquid is neutralized to a pH of 2-3 using a neutralizing agent. After liquid-solid separation, a germanium-precipitating agent is added to the neutralized liquid, and germanium is precipitated at 70-85°C to obtain germanium-rich slag. The hydrogen ion concentration in the copper- and germanium-containing wet zinc leaching solution is 0.1-0.5 mol / L. This invention achieves copper-germanium separation by employing a stepwise selective precipitation method, using a strategy of first precipitating copper and then precipitating germanium.

[0006] Furthermore, the seed crystals added during the copper plating process are copper sulfide, and the amount of seed crystals added is 2~5 g / L. The particle size of the copper sulfide seed crystals is less than 74 micrometers, preferably 45 micrometers to 74 micrometers.

[0007] Furthermore, the hydrogen sulfide gas is added at 1.0 to 1.4 times the theoretical amount required for copper precipitation, preferably 1.0 to 1.2 times, which includes 1.0 to 1.15 times. In this invention, the theoretical amount of copper for precipitation refers to the amount calculated according to the chemical reaction formula Cu... 2+ + H2S = CuS + 2H + The theoretical amount used for measurement.

[0008] Furthermore, air is introduced into the upper space of the sealed reactor to maintain the pressure inside the sealed reactor at 0.1~0.3MPa.

[0009] Furthermore, a wet zinc leaching solution containing copper and germanium is added to a sealed reactor. Seed crystals are added to the solution, followed by hydrogen sulfide gas. The reaction is carried out at 70-95°C and a pressure of 0.1-0.3 MPa, preferably 0.15-0.3 MPa, and more preferably 0.2-0.3 MPa, with stirring for 15-30 minutes. The optimized pressure of 0.15-0.3 MPa in this invention is chosen to increase the solubility and utilization efficiency of hydrogen sulfide in the solution. If the pressure is too low, hydrogen sulfide is difficult to dissolve, and most of it enters the gas phase, resulting in low hydrogen sulfide utilization.

[0010] In this invention, the temperature is controlled at 70-95°C, preferably 85-95°C, after introducing hydrogen sulfide gas. This temperature range is beneficial for obtaining well-crystallized copper sulfide precipitate. If the temperature is too low, the precipitated copper sulfide will have poor crystallinity, high water content, and low copper content. If the temperature is too high, unreacted hydrogen sulfide will easily enter the exhaust gas along with water vapor, resulting in low hydrogen sulfide utilization and increased safety risks of hydrogen sulfide poisoning.

[0011] Furthermore, the neutralizing agent used in the germanium precipitation solution is zinc oxide powder, and the reaction time is greater than or equal to 20 min, preferably 30 to 120 min, including 30 to 60 min.

[0012] Furthermore, the germanium precipitation agent is zinc powder with a particle size of less than 74 micrometers, and the reaction time is greater than or equal to 60 min, preferably 90 to 150 min, including 90 to 120 min.

[0013] Furthermore, the present invention precipitates germanium at 70~85℃ because the germanium grade in the precipitated germanium product is high. If the temperature is too high, it will cause co-precipitation of impurity ions coexisting in the solution, resulting in low germanium content in the precipitated germanium product. If the temperature is too low, it will cause low reaction efficiency of the germanium precipitation agent, large consumption of the germanium precipitation agent, and low germanium content in the germanium enrichment.

[0014] Furthermore, the concentration of copper ions in the wet zinc smelting leaching solution is 0.5~2g / L, the concentration of germanium ions is 20~150mg / L, the concentration of hydrogen ions is 0.1~0.5mol / L, and the concentration of ferric ions is less than 1g / L.

[0015] The beneficial effects of this invention are:

[0016] (1) High copper-germanium separation efficiency. This invention adopts a stepwise selective precipitation method to obtain copper-rich slag and germanium-rich slag respectively. Through innovation and optimization of germanium precipitation agent and precipitation process, copper-germanium separation is achieved with a copper precipitation rate of more than 96% and a germanium precipitation rate of more than 98%, resulting in high copper-germanium separation efficiency; and the content of germanium in the copper precipitation product is very low.

[0017] (2) High utilization efficiency of germanium precipitator and low reagent consumption. This invention uses a closed reactor for selective copper precipitation, utilizes seed crystal induction, and uses air as a pressurizing medium to increase the solubility of hydrogen sulfide in the solution, thereby improving the copper precipitation efficiency. The utilization efficiency of germanium precipitator is high, reaching over 95%.

[0018] (3) The product has high copper and germanium content, and a high degree of copper and germanium enrichment. The copper-rich slag produced by the method of this invention has a copper content ≥20% and a germanium content of less than 30 g / t (which can be as low as ≤18 g / t after optimization), and the copper mainly exists in the form of copper sulfide, which is convenient for use as a raw material for subsequent copper smelting. The germanium-rich slag produced has a germanium content ≥6000 g / t and a high germanium enrichment factor.

[0019] (4) The copper plating process of this invention uses a closed reactor, with no harmful gas leakage, and the process is clean, efficient and environmentally friendly. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0021] Example 1

[0022] 1000 mL of wet zinc leaching solution was taken, containing copper ions at a concentration of 1.0 g / L, germanium ions at a concentration of 50 mg / L, free sulfuric acid at a concentration of 30 g / L, ferric ions at a concentration of 100 mg / L, and zinc ions at a concentration of 105 g / L. This copper- and germanium-containing wet zinc leaching solution was added to a 2 L sealed reactor. 3 g / L of copper sulfide (particle size ≤ 74 μm) was added as seed crystals. Hydrogen sulfide gas, with a theoretical mass ratio of 1.1 times that of copper precipitation, was then slowly added. Air was introduced into the upper space of the sealed reactor to maintain a pressure of 0.2 MPa. The reaction was carried out at 90 °C with stirring for 20 min. After the reaction, the mixture was filtered to obtain a solid copper precipitate product containing 44.1% copper and 15 g / t germanium, with a copper precipitation rate of 98%. The germanium ion concentration in the copper precipitation solution was 49.5 mg / L. 35 g / L of zinc oxide powder was added as a neutralizing agent to neutralize the solution to pH 2.5. The solution was then filtered, with no germanium loss during this process. 5.5 g / L of zinc powder was added as a germanium precipitating agent to the neutralized solution, and germanium was precipitated at 80℃ for 120 min. Filtration yielded germanium-rich slag containing 8502 g / t of germanium. The germanium concentration in the precipitated solution was 2 mg / L, resulting in a germanium precipitation rate of 96%.

[0023] Exploratory Example 1-1

[0024] The raw materials and other conditions were the same as in Example 1, except that hydrogen sulfide gas was added at a theoretical mass ratio of 0.8 times that of copper precipitation. The obtained copper precipitate contained 48.5% copper and 10 g / t germanium, with a copper precipitation rate of 85%. The obtained germanium-rich slag contained 6075 g / t germanium, and the germanium concentration in the precipitate was 1.6 mg / L, with a germanium precipitation rate of 96.8%.

[0025] Exploratory Examples 1-2

[0026] The raw materials and other conditions were the same as in Example 1, except that hydrogen sulfide gas, at a theoretical mass multiple of 1.0 times that of copper precipitation, was added. The obtained copper-precipitated product contained 45.2% copper and 12 g / t germanium, with a copper precipitation rate of 92%. The obtained germanium-rich slag contained 7121 g / t germanium, and the germanium concentration in the post-precipitation solution was 1.8 mg / L, with a germanium precipitation rate of 96.4%.

[0027] Exploratory Examples 1-3

[0028] The raw materials and other conditions were the same as in Example 1, except that hydrogen sulfide gas, at a theoretical mass multiple of 1.2 times, was added. The obtained copper-plated product contained 40.3% copper and 18 g / t germanium, with a copper precipitation rate of 98.7%. The obtained germanium-rich slag contained 9283 g / t germanium, the germanium concentration in the post-precipitation liquid was 2.2 mg / L, and the germanium precipitation rate was 95.6%.

[0029] Exploratory Examples 1-4

[0030] The raw materials and other conditions were the same as in Example 1, except that hydrogen sulfide gas, at a theoretical mass multiple of 1.4 times that of copper precipitation, was added. The obtained copper-precipitated product contained 38.2% copper and 45 g / t germanium, with a copper precipitation rate of 99.2%. The obtained germanium-rich slag contained 9825 g / t germanium, the germanium concentration in the post-precipitation liquid was 2.5 mg / L, and the germanium precipitation rate was 95.0%.

[0031] Exploratory Examples 1-5

[0032] The raw materials and other conditions were the same as in Example 1, except that air was introduced into the upper space of the sealed reactor or water vapor was removed to maintain the pressure inside the sealed reactor at 0.1 MPa. The obtained copper-precipitated product contained 43.1% copper and 17 g / t germanium, with a copper precipitation rate of 97.1%. The obtained germanium-rich slag contained 8210 g / t germanium, and the germanium concentration in the post-precipitation liquid was 2.2 mg / L, with a germanium precipitation rate of 95.6%.

[0033] Explore 1-6

[0034] The raw materials and other conditions are the same as in Example 1, except that:

[0035] Air was introduced into the upper space of a sealed reactor to maintain a pressure of 0.2 MPa. The reaction was carried out at 95°C with stirring for 20 minutes. The obtained copper-precipitated product contained 47.2% copper and 16 g / t germanium, with a copper precipitation rate of 98.1%. The obtained germanium-rich slag contained 8321 g / t germanium, and the germanium concentration in the post-precipitation liquid was 1.9 mg / L, with a germanium precipitation rate of 96.2%.

[0036] Explore 1-7

[0037] The raw materials and other conditions are the same as in Example 1, except that:

[0038] Air was introduced into the upper space of a sealed reactor to maintain a pressure of 0.2 MPa. The reaction was carried out at 100°C with stirring for 20 minutes. The obtained copper-precipitated product contained 48.3% copper and 13 g / t germanium, with a copper precipitation rate of 96.1%. The obtained germanium-rich slag contained 6526 g / t germanium, and the germanium concentration in the post-precipitation solution was 2.5 mg / L, with a germanium precipitation rate of 95%.

[0039] Explore 1-8

[0040] The raw materials and other conditions were the same as in Example 1, except that 5.5 g / L zinc powder was added to the neutralized liquid as a germanium precipitant, germanium was precipitated at 70°C for 120 min, and the residue was filtered to obtain germanium-rich slag. The germanium-rich slag contained 7328 g / t of germanium, the germanium concentration in the precipitated liquid was 2.2 mg / L, and the germanium precipitation rate was 95.6%.

[0041] Explore 1-9

[0042] The raw materials and other conditions were the same as in Example 1, except that 5.5 g / L zinc powder was added to the neutralized liquid as a germanium precipitant, germanium was precipitated at 50°C for 120 min, and the residue was filtered to obtain germanium-rich slag. The germanium-rich slag contained 3162 g / t of germanium, the germanium concentration in the precipitated liquid was 12.8 mg / L, and the germanium precipitation rate was 83.6%.

[0043] Explore 1-10

[0044] The raw materials and other conditions were the same as in Example 1, except that 5.5 g / L zinc powder was added to the neutralized liquid as a germanium precipitant, germanium was precipitated at 85°C for 120 min, and the residue was filtered to obtain germanium-rich slag. The germanium-rich slag contained 7669 g / t of germanium, the germanium concentration in the precipitated liquid was 3.8 mg / L, and the germanium precipitation rate was 94.4%.

[0045] Explore 1-11

[0046] The raw materials and other conditions were the same as in Example 1, except that 5.5 g / L zinc powder was added to the neutralized liquid as a germanium precipitant, germanium was precipitated at 100°C for 120 min, and the residue was filtered to obtain germanium-rich slag. The germanium-rich slag contained 4212 g / t of germanium, the germanium concentration in the precipitated liquid was 17.6 mg / L, and the germanium precipitation rate was 65.6%.

[0047] Example 2

[0048] 1000 mL of wet zinc leaching solution was taken, containing copper ions at a concentration of 1.25 g / L, germanium ions at 35 mg / L, free sulfuric acid at 21 g / L, ferric ions at 120 mg / L, and zinc ions at 95 g / L. This copper- and germanium-containing wet zinc leaching solution was added to a 2 L sealed reactor. 4 g / L of copper sulfide (particle size ≤ 74 μm) was added as seed crystals. Hydrogen sulfide gas, with a theoretical copper deposition ratio of 1.15 times, was then slowly added. Air was introduced into the upper space of the sealed reactor to maintain a pressure of 0.3 MPa. The reaction was carried out at 85 °C with stirring for 25 min. After the reaction, the mixture was filtered to obtain a copper-precipitated solid product. This product contained 43.6% copper and 18 g / t germanium, with a copper precipitation rate of 98%. The germanium ion concentration in the copper precipitation solution was 34.8 mg / L. 26 g / L of zinc oxide powder was added as a neutralizing agent to neutralize the solution to pH 2.0. The solution was then filtered, with no germanium loss during this process. 7.8 g / L of zinc powder was added as a germanium precipitating agent to the neutralized solution, and germanium was precipitated at 80℃ for 100 min. Filtration yielded germanium-rich slag containing 7385 g / t of germanium. The germanium concentration in the precipitated solution was 2 mg / L, resulting in a germanium precipitation rate of 95.9%.

[0049] Example 3

[0050] 1000 mL of wet zinc leaching solution was taken, containing copper ions at a concentration of 1.55 g / L, germanium ions at 30 mg / L, free sulfuric acid at 25 g / L, ferric ions at 150 mg / L, and zinc ions at 100 g / L. This copper- and germanium-containing wet zinc leaching solution was added to a 2 L sealed reactor. 5 g / L of copper sulfide (particle size ≤ 74 μm) was added as seed crystals. Hydrogen sulfide gas, with a theoretical copper deposition ratio of 1.2 times, was then slowly added. Air was introduced into the upper space of the sealed reactor to maintain a pressure of 0.2 MPa. The reaction was carried out at 85 °C with stirring for 30 min. After the reaction, the mixture was filtered to obtain a copper-precipitated solid product. This product contained 46.2% copper and 12 g / t germanium, with a copper precipitation rate of 98.5%. The germanium ion concentration in the copper precipitation solution was 29.9 mg / L. 31 g / L of zinc oxide powder was added as a neutralizing agent to neutralize the solution to pH 2.2. The solution was then filtered, with no germanium loss during this process. 6.6 g / L of zinc powder was added to the neutralized solution as a germanium precipitating agent, and germanium was precipitated at 80℃ for 90 min. Filtration yielded germanium-rich slag containing 6503 g / t of germanium. The germanium concentration in the precipitated solution was 1.7 mg / L, resulting in a germanium precipitation rate of 94.3%.

[0051] Example 4

[0052] 1000 mL of wet zinc leaching solution was taken, containing copper ions at a concentration of 1.95 g / L, germanium ions at 21 mg / L, free sulfuric acid at 15 g / L, ferric ions at 90 mg / L, and zinc ions at 110 g / L. This copper- and germanium-containing wet zinc leaching solution was added to a 2 L sealed reactor. 2 g / L of copper sulfide (particle size ≤ 74 μm) was added as seed crystals. Hydrogen sulfide gas, with a theoretical copper deposition ratio of 1.1 times, was then slowly added. Air was introduced into the upper space of the sealed reactor to maintain a pressure of 0.2 MPa. The reaction was carried out at 80 °C with stirring for 25 min. After the reaction, the mixture was filtered to obtain a copper-precipitated solid product. This copper-precipitated product contained 44.5% copper and 13 g / t germanium, with a copper precipitation rate of 99.1%. The germanium ion concentration in the copper-precipitated solution was 20.8 mg / L. 18 g / L of zinc oxide powder was added as a neutralizing agent to neutralize the solution to pH 3.0. The solution was then filtered, with no germanium loss during this process. 5 g / L of zinc powder was added to the neutralized solution as a germanium precipitating agent, and germanium was precipitated at 80℃ for 110 min. Filtration yielded germanium-rich slag containing 6021 t of germanium. The germanium concentration in the precipitated solution was 1.5 mg / L, resulting in a germanium precipitation rate of 92.8%.

[0053] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for separating copper and germanium from a wet zinc smelting leaching solution, characterized in that... The process includes the following steps: adding a wet zinc leaching solution containing copper and germanium into a closed reactor, adding seed crystals to the solution, and then adding hydrogen sulfide gas. The reaction is carried out at 70-95℃ and 0.1-0.3MPa for 5-30 minutes with stirring. After the reaction is completed, the solution is filtered to obtain a copper-precipitated solid product. Germanium does not precipitate and is retained in the copper-precipitated liquid. The copper-precipitated liquid is neutralized to pH 2-3 with a neutralizing agent. After liquid-solid separation, a germanium-precipitating agent is added to the neutralized liquid and germanium is precipitated at 70-85℃ to obtain germanium-rich slag.

2. The method for separating copper and germanium from a wet zinc smelting leaching solution according to claim 1, characterized in that: The seed crystals added during the copper plating process are copper sulfide, and the amount of seed crystals added is 2~5g / L.

3. The method for separating copper and germanium from wet zinc smelting leaching solution according to claim 2, characterized in that: The copper sulfide seed crystals have a particle size of less than 74 micrometers.

4. The method for separating copper and germanium from a wet zinc smelting leaching solution according to claim 1, characterized in that: The mass of hydrogen sulfide gas added is 1.0 to 1.4 times the theoretical amount required for copper precipitation.

5. The method for separating copper and germanium from a wet zinc smelting leaching solution according to claim 1, characterized in that: Air is introduced into the upper space of the sealed reactor to maintain the pressure inside the sealed reactor at 0.1~0.3MPa.

6. The method for separating copper and germanium from a wet zinc smelting leaching solution according to claim 1, characterized in that: After introducing hydrogen sulfide gas, the temperature is controlled at 85~95℃ for copper plating.

7. The method for separating copper and germanium from a wet zinc smelting leaching solution according to claim 1, characterized in that: After germanium precipitation, the neutralizing agent used is zinc oxide powder, and the reaction time is 30-60 minutes.

8. The method for separating copper and germanium from a wet zinc smelting leaching solution according to claim 1, characterized in that: The germanium precipitation agent is zinc powder with a particle size of less than 74 micrometers, and the reaction time is 90~120 min.

9. The method for separating copper and germanium from a wet zinc smelting leaching solution according to claim 1, characterized in that: The concentration of copper ions in the wet zinc smelting leaching solution is 0.5~2g / L, the concentration of germanium ions is 20~150mg / L, the concentration of hydrogen ions is 0.1~0.5mol / L, and the concentration of ferric ions is less than 500mg / L.