Method for selectively leaching germanium based on acidity gradient regulation and control

Abstract

The invention discloses a method for selectively leaching germanium based on acidity gradient regulation and control, and relates to the technical field of hydrometallurgy and rare metal recovery. Comprising the following steps: performing neutral leaching on a germanium-containing raw material to obtain neutral leaching liquid and neutral leaching residues; the neutral leaching residues are subjected to weak acid leaching, and weak acid leaching liquid and weak acid leaching residues are obtained; the weak acid leaching residues are subjected to high-acid leaching, meanwhile, sulfur dioxide is introduced for enhanced leaching, high-acid leaching liquid and high-acid leaching residues are obtained, the high-acid leaching residues are pulpified through the high-acid leaching liquid, and high-acid germanium-rich ore pulp is obtained; the high-acid germanium-rich ore pulp is subjected to ultrahigh-acid leaching, and ultrahigh-acid leaching liquid and ultrahigh-acid leaching residues are obtained; wherein the germanium recovery rate in the ultra-high acid leaching solution is greater than 80%. According to the method, the acidity, the temperature and the reduction leaching conditions are accurately controlled, the germanium recovery rate is maximized, selective separation is achieved, the process is simple, the cost is low, remarkable economic benefits are achieved, and the method has wide application prospects in the field of resource reutilization of germanium-containing smoke dust, germanium-containing slag and other complex raw materials.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy and rare metal recovery, and in particular to a method for selectively leaching germanium based on acidity gradient regulation. Background Art

[0002] As a strategic rare metal, germanium is irreplaceable in cutting-edge technology fields such as fiber optic communications, infrared thermal imaging, and solar cells due to its unique optoelectronic properties. However, independent deposits of germanium are extremely rare in nature, and its occurrence is mostly distributed in the sphalerite lattice in an isomorphous form (accounting for about 70%), or enriched in secondary resources such as smelting dust (such as zinc oxide dust containing 0.01%-0.1% germanium), leaching slag, etc. Therefore, the efficient extraction and enrichment technology of germanium has become a key link that restricts the stability of the downstream high-end manufacturing industry chain. In the current industrial system, hydrometallurgical technology has become the mainstream process for germanium resource recovery due to its environmental friendliness and metal selectivity advantages. Its core process usually includes a two-stage leaching process.

[0003] In the traditional two-stage leaching process, neutral leaching is first used to dissolve the soluble metals and enrich the germanium in the intermediate leaching residue as much as possible. Subsequently, the acid leaching is used to treat the intermediate leaching residue to allow the germanium to enter the solution, thereby achieving recovery. However, this method still has certain limitations. First, the acidity control in the acid leaching stage is relatively simple, and it is difficult to take into account both the efficient dissolution of germanium and the selective leaching of other impurity metals at the same time, resulting in some germanium remaining in the residue and limiting the recovery rate. In addition, in a high acid environment, Fe 3+ Impurity ions such as ions easily form stable complexes with germanium, which increases the subsequent purification load and causes germanium loss. At the same time, during the acid leaching process, the oxidation potential of the system causes some Ge 2+ Oxidized to insoluble GeO2. Summary of the Invention

[0004] To this end, the purpose of the present invention is to develop a germanium enrichment process that takes into account acidity gradient adaptability, impurity selective suppression and self-consistency of the reduction process, which has an urgent industrial demand for improving resource utilization and reducing overall production costs.

[0005] The above invention objectives are achieved through the following technical solutions:

[0006] A method for selectively leaching germanium based on acidity gradient regulation comprises the following steps:

[0007] S1: neutral leaching of the germanium-containing raw material to obtain intermediate leaching solution and intermediate leaching residue;

[0008] S2: subjecting the intermediate leaching residue to weak acid leaching to obtain weak acid leaching solution and weak acid leaching residue;

[0009] S3: subjecting the weak acid leaching residue to high acid leaching, while introducing sulfur dioxide to enhance leaching, to obtain high acid leaching solution and high acid leaching residue; slurrying the high acid leaching residue with the high acid leaching solution to obtain high acid germanium-rich ore pulp;

[0010] S4: subjecting the high-acid, germanium-rich slurry to ultra-high acid leaching to obtain ultra-high acid leaching solution and ultra-high acid leaching residue; wherein the germanium recovery rate in the ultra-high acid leaching solution is greater than 80%.

[0011] Furthermore, the germanium-containing raw material includes germanium-containing smoke and / or germanium-containing slag.

[0012] Furthermore, the germanium-containing raw material is zinc oxide fume, and the germanium content in the zinc oxide fume is 0.01%-0.1% by mass.

[0013] Furthermore, in the method, the neutral leaching temperature is controlled to be less than the weak acid leaching temperature and less than the high acid leaching temperature.

[0014] Furthermore, the neutral leaching in step S1 includes: using wet zinc electrolysis waste liquid as a leaching agent, controlling the liquid-solid ratio to (3-5) mL:1 g, the temperature to 70°C-80°C, the time to 3h-5h, and the endpoint pH to 5.0-6.0.

[0015] Furthermore, the weak acid leaching in step S2 includes: using wet zinc electrolysis waste liquid as a leaching agent, controlling the liquid-solid ratio to (4-6) mL:1 g, the temperature to 75° C. to 85° C., the time to 7 h to 9 h, and the endpoint pH to 2.0-3.0.

[0016] Furthermore, the high-acid leaching in step S3 includes: using wet zinc smelting electrolytic waste liquid as a leaching agent, controlling the liquid-solid ratio to (4-6) mL:1 g, the temperature to 80° C. to 90° C., the time to 8 h to 10 h, and the endpoint sulfuric acid concentration to 70 g / L to 90 g / L.

[0017] Furthermore, in step S3, sulfur dioxide is introduced simultaneously to enhance leaching, with 0.5 L to 1.0 L of sulfur dioxide introduced per liter of pulp per hour, and the sulfur dioxide introduction time is 3 hours to 5 hours.

[0018] Furthermore, in step S3, the high-acid leaching residue is slurried with the high-acid leaching liquid, and the liquid-to-solid ratio of the high-acid leaching liquid to the high-acid leaching residue is controlled to be (2-3) mL:1 g.

[0019] Furthermore, the ultra-high acid leaching in step S4 includes: adding concentrated sulfuric acid to the high-acid germanium-rich slurry to adjust the acidity, controlling the sulfuric acid concentration in the obtained ultra-high acid leaching solution to be 170g / L-190g / L, the temperature to be 90°C-93°C, and the time to be 8h-10h.

[0020] Compared with the existing technology, the present invention has at least the following beneficial effects:

[0021] The method for selectively leaching germanium based on acidity gradient regulation provided by the present invention achieves maximum germanium recovery and selective separation by precisely controlling acidity, temperature and reduction leaching conditions. The process is simple, cost-effective, and feasible, with significant economic benefits. The method is suitable for the treatment of various germanium-containing minerals, especially in the field of resource recycling of complex raw materials such as germanium-containing smoke and germanium-containing slag, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A process flow chart for selectively leaching germanium based on acidity gradient regulation provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to better understand the above technical solution, the technical solution of the present invention is described in detail below through specific embodiments.

[0024] An embodiment of the present invention provides a method for selectively leaching germanium based on acidity gradient control, comprising the following steps:

[0025] S1: neutral leaching of the germanium-containing raw material to obtain intermediate leaching solution and intermediate leaching residue;

[0026] S2: subjecting the intermediate leaching residue to weak acid leaching to obtain weak acid leaching solution and weak acid leaching residue;

[0027] S3: subjecting the weak acid leaching residue to high acid leaching, while introducing sulfur dioxide for enhanced leaching, to obtain high acid leaching solution and high acid leaching residue; the high acid leaching residue is slurried with the high acid leaching solution to obtain high acid germanium-rich ore pulp;

[0028] S4: subjecting the high-acid germanium-rich slurry to ultra-high acid leaching to obtain ultra-high acid leaching solution and ultra-high acid leaching residue; wherein the germanium recovery rate in the ultra-high acid leaching solution is greater than 80%.

[0029] The embodiment of the present invention provides a method for selectively leaching germanium based on acidity gradient control, which gradually controls neutral leaching, weak acid leaching, high acid leaching and ultra-high acid leaching, and combines the reducing atmosphere created by sulfur dioxide to effectively reduce Fe 3+ , Pb 2+ The interference of impurities such as 2+ Oxidation forms insoluble GeO2, which significantly improves the recovery rate of germanium.

[0030] Furthermore, through staged leaching and precise acidity control, excessive acid use is avoided and Fe 3+ , Pb 2+The co-leaching of impurities such as SO2 and SO2 can reduce the subsequent purification load and acid consumption costs. In addition, the optimized SO2 reducing atmosphere adjustment avoids excessive consumption of external reducing agents.

[0031] In some embodiments, the germanium-containing raw material includes germanium-containing fume and / or germanium-containing slag.

[0032] Specifically, the acidity is precisely controlled in stages through neutral leaching-weak acid leaching-high acid leaching-ultra-high acid leaching to achieve maximum germanium recovery and selective separation. The process is simple, low-cost, and highly feasible, with significant economic benefits. It is applicable to a variety of germanium-containing secondary resources, especially in the field of resource recycling of complex raw materials such as germanium-containing smoke and germanium-containing slag, and has broad application prospects.

[0033] In some embodiments, the germanium-containing raw material is zinc oxide fume, and the germanium content in the zinc oxide fume is 0.01%-0.1% by mass.

[0034] Specifically, the phased acidity control method of neutral leaching, weak acid leaching, high acid leaching, and ultra-high acid leaching is particularly suitable for recovering germanium from zinc oxide dust. This avoids the low germanium leaching rate and severe impurity co-leaching caused by single acidity control in traditional processes. By gradually dissolving zinc in the neutral leaching (pH = 5.0-6.0) and weak acid leaching (pH = 2.0-3.0) stages, germanium and indium are enriched in the intermediate leaching residue, creating favorable conditions for subsequent high acid and ultra-high acid leaching.

[0035] In some embodiments, in the method for controlling the selective leaching of germanium based on the acidity gradient, the neutral leaching temperature is less than the weak acid leaching temperature and less than the high acid leaching temperature.

[0036] Specifically, the neutral leaching temperature is controlled to be less than the weak acid leaching temperature and less than the high acid leaching temperature, and less than the ultra-high acid leaching temperature. During the leaching process, optimized control is adopted in different temperature ranges, and the leaching temperature is gradually increased. The temperature is controlled at 70°C to 80°C in the neutral leaching stage, increased to 75°C to 85°C in the weak acid leaching stage, and further increased to 80°C to 90°C and 90°C to 93°C in the high acid and ultra-high acid leaching stages. This optimized design accelerates the dissolution of indium and germanium, increases the leaching rate, reduces acid consumption, and improves resource utilization efficiency.

[0037] In some embodiments, the neutral leaching in step S1 includes: using wet zinc electrolysis waste liquid as a leaching agent, controlling the liquid-solid ratio to (3-5) mL:1 g, the temperature to 70°C to 80°C, the time to 3h to 5h, and the endpoint pH to 5.0-6.0.

[0038] Specifically, through neutral leaching, (1) soluble metals are dissolved and impurity interference is reduced. Under neutral conditions, soluble metal ions such as zinc preferentially enter the solution, significantly reducing the interference load of impurity metals in subsequent steps, creating conditions for the enrichment and selective leaching of germanium. (2) The germanium in the germanium-containing material is activated. Through neutral leaching, the encapsulated germanium-containing components in the raw material are released and converted into easily leached components that are retained in the intermediate leaching residue, creating conditions for the subsequent leaching of germanium.

[0039] In some embodiments, the weak acid leaching in step S2 includes: using wet zinc smelting electrolytic waste liquid as a leaching agent, controlling the liquid-solid ratio to (4-6) mL: 1 g, the temperature to 75° C. to 85° C., the time to 7 h to 9 h, and the endpoint pH to 2.0-3.0.

[0040] Specifically, weak acid leaching further removes soluble impurities such as zinc and iron from the intermediate leaching residue. After neutral leaching, some residual zinc, iron, and other associated impurities remain in the intermediate leaching residue. Weak acid leaching effectively dissolves these impurities, particularly sparingly soluble zinc salts, facilitating subsequent germanium enrichment.

[0041] Furthermore, in traditional processes, zinc and indium often coexist in the intermediate leaching residue, and high zinc content can interfere with the subsequent separation and recovery of indium. The present invention adds a weak acid leaching stage (pH = 2.0-3.0) after neutral leaching to further dissolve residual zinc and reduce the zinc content in the intermediate leaching residue, thereby reducing zinc interference in the subsequent indium recovery process and improving the subsequent purification efficiency of indium.

[0042] In some embodiments, the high-acid leaching in step S3 includes: using wet zinc smelting electrolytic waste liquid as a leaching agent, controlling the liquid-solid ratio to (4-6) mL: 1 g, the temperature to 80° C. to 90° C., the time to 8 h to 10 h, the endpoint sulfuric acid concentration to 70 g / L to 90 g / L, and simultaneously introducing sulfur dioxide for enhanced leaching, introducing 0.5 L to 1.0 L of sulfur dioxide into the pulp per hour during each increase in acid leaching, the sulfur dioxide introduction time to 3 h to 5 h, and controlling the liquid-solid ratio of the high-acid leaching solution to the high-acid leaching slag to be (2-3) mL: 1 g.

[0043] Specifically, through high acid leaching, (1) germanium is leached. In the neutral and weak acid stages, germanium is mainly enriched in the leaching residue. When the reaction reaches the high acid stage, in a strong acidic environment, germanium begins to leach into the solution. The sulfuric acid concentration reaches 70-90g / L, which can significantly increase the dissolution rate of Ge. (2) A reducing environment is constructed to increase the leaching rate of germanium. In this step, SO2 gas is introduced to keep the leaching system reducing, which effectively inhibits the reduction of Ge. 2+Oxidation to insoluble GeO2 avoids secondary precipitation of germanium under high acid and high temperature conditions; on the other hand, it reduces the zinc ferrite in the material, releases the germanium wrapped by the zinc ferrite, and improves the leaching rate of germanium; in addition, this process can reduce Pb 2+ The co-leaching of impurity metals such as chlorinated bicarbonate and chlorinated bicarbonate can improve the subsequent germanium purification efficiency.

[0044] In some embodiments, the ultra-high acid leaching in step S4 includes: adding concentrated sulfuric acid to the high-acid germanium-rich slurry to adjust the acidity, controlling the sulfuric acid concentration in the obtained ultra-high acid leaching solution to 170 g / L to 190 g / L, the temperature to 90° C. to 93° C., and the time to 8 h to 10 h.

[0045] Specifically, ultra-high acid leaching further removes residual germanium from high-acid slag, improving overall recovery. After high-acid reduction leaching, a small amount of germanium remains unleached, particularly in the presence of lattice nesting, physical encapsulation, or weak adsorption. The ultra-high acid environment possesses exceptional solubility and fragmentation capabilities, further dissolving the germanium and increasing its leaching rate.

[0046] Example 1 A method for selectively leaching germanium from zinc oxide dust based on acidity gradient control

[0047] like Figure 1 As shown, the following steps are included:

[0048] S1: 129 g of germanium-containing zinc oxide fume (containing germanium at a mass fraction of 0.011%) produced by a certain factory was taken as raw material, ball-milled to a -200 mesh size of ≥85%, and then slowly placed into 500 mL of hydrometallurgical zinc electrolysis waste liquid for neutral leaching, wherein the sulfuric acid concentration of the hydrometallurgical zinc electrolysis waste liquid was 170 g / L, the heating temperature was controlled at 80°C, stirred and leached for 4 hours, and the reaction end point pH was 5.5. After liquid-solid separation, an intermediate leaching solution and an intermediate leaching residue were obtained. The intermediate leaching solution was returned to the main hydrometallurgical zinc smelting system to recover zinc, and the intermediate leaching residue was used for subsequent further enrichment of germanium.

[0049] S2: The intermediate leaching residue obtained in S1 is slurried with hydrometallurgical zinc electrolysis waste liquid, wherein the sulfuric acid concentration of the hydrometallurgical zinc electrolysis waste liquid is 170g / L, the liquid-solid ratio is 6mL:1g, the temperature is controlled at 84°C, the leaching time is 8h, the end point pH=2.5, and after liquid-solid separation, weak acid leaching solution and weak acid leaching residue are obtained. The weak acid leaching solution is returned to neutral leaching, and the weak acid leaching residue is used for subsequent further enrichment of germanium.

[0050] S3: Take the weak acid leaching residue in S2, add hydrometallurgical zinc electrolysis waste liquid to slurry, and introduce sulfur dioxide gas for 3 hours to perform high-acid reduction leaching, wherein the sulfuric acid concentration of the hydrometallurgical zinc electrolysis waste liquid is 170g / L, the liquid-solid ratio is 5mL:1g, the temperature is controlled at 90°C, and the leaching is stirred for 9 hours. The sulfuric acid concentration at the end point of the reaction is 75g / L, and high-acid leaching liquid and high-acid leaching residue are obtained. The high-acid leaching residue is slurried with the high-acid leaching liquid, and the liquid-solid ratio is controlled to be 2mL:1g to obtain high-acid germanium-rich ore pulp.

[0051] S4: adding concentrated sulfuric acid to the high-acid germanium-rich slurry obtained in S3 to adjust the acidity and perform ultra-high acid leaching, wherein the temperature is controlled at 90°C, stirring and leaching is carried out for 8 hours, the acidity of the solution at the end of the reaction is 170g / L, and ultra-high acid leaching liquid and ultra-high acid leaching residue are obtained after liquid-solid separation.

[0052] The experimental results show that after the zinc oxide dust is subjected to neutral leaching-weak acid leaching-high acid leaching-ultra-high acid leaching combined with sulfur dioxide gas reduction, the leaching rate of germanium in the ultra-high acid leaching solution (germanium-rich leaching solution) is 81.1%.

[0053] Example 2 A method for selectively leaching germanium from zinc oxide dust based on acidity gradient control

[0054] like Figure 1 As shown, the following steps are included:

[0055] S1: 130g of germanium-containing zinc oxide dust from a certain factory (containing 0.0112% germanium by mass) was taken as raw material. After ball milling to a -200 mesh size of ≥86%, 500mL of hydrometallurgical zinc electrolysis wastewater (sulfuric acid concentration of 180g / L) was slowly added. The mixture was heated to 73°C and stirred for 4 hours. The reaction endpoint pH was 5.0. After liquid-solid separation, the resulting intermediate leachate was returned to the main hydrometallurgical zinc smelting system for zinc recovery, and the intermediate leach residue was used for subsequent germanium enrichment.

[0056] S2: The intermediate leaching residue obtained in S1 is slurried with hydrometallurgical zinc electrolysis wastewater (sulfuric acid concentration 180g / L) at a liquid-to-solid ratio of 6mL:1g, a temperature of 82°C, and a leaching time of 7.5h, with an endpoint pH of 2.8. After liquid-solid separation, a weak acid leaching solution and weak acid leaching residue are obtained. The weak acid leaching solution is returned to the main hydrometallurgical zinc smelting system for zinc recovery, and the weak acid leaching residue is used for subsequent further enrichment of germanium.

[0057] S3: Take the weak acid leaching residue in S2, slurry it with wet zinc electrolysis waste liquid (sulfuric acid concentration 180g / L), and introduce sulfur dioxide gas for 3.5h for high acid reduction leaching, with a liquid-solid ratio of 5mL:1g, temperature 90℃, stirring leaching for 9.5h, and end point sulfuric acid concentration 74g / L, to obtain high acid leaching solution and high acid leaching residue, slurry the high acid leaching residue with high acid leaching solution, control the liquid-solid ratio to 3mL:1g, and obtain high acid germanium-rich ore pulp.

[0058] S4: adding concentrated sulfuric acid to the high-acid germanium-rich slurry obtained in S3 to adjust the acidity and perform ultra-high acid leaching, wherein the temperature is 91°C, the stirring leaching is carried out for 8 hours, the end point sulfuric acid concentration is 172 g / L, and ultra-high acid leaching liquid and ultra-high acid leaching residue are obtained after liquid-solid separation.

[0059] The experimental results show that after the zinc oxide fume is treated by the process of Example 2, the leaching rate of germanium in the ultra-high acid leaching solution (germanium-rich leaching solution) is 81.5%.

[0060] Example 3 A method for selectively leaching germanium from zinc oxide dust based on acidity gradient control

[0061] like Figure 1 As shown, the following steps are included:

[0062] S1: 125g of germanium-containing zinc oxide dust (0.0108% germanium) from a certain factory was ball-milled to a -200 mesh density of ≥85%. 500mL of hydrometallurgical zinc electrolysis wastewater (sulfuric acid concentration: 170g / L) was then slowly added. The mixture was heated to 71°C and stirred for 4 hours, with the pH reaching 5.3 at the end of the reaction. After liquid-solid separation, the resulting intermediate leachate was returned to the main hydrometallurgical system for zinc recovery, and the intermediate leach residue was used for subsequent germanium enrichment.

[0063] S2: The intermediate leaching residue obtained in S1 was slurried with hydrometallurgical zinc electrolysis wastewater (sulfuric acid concentration 170g / L) at a liquid-solid ratio of 5.8mL:1g, at a temperature of 82°C, and stirred for 8 hours, with an endpoint pH of 2.6. After liquid-solid separation, weak acid leaching solution and weak acid leaching residue were obtained.

[0064] S3: Take the weak acid leaching residue in S2, slurry it with wet zinc electrolysis waste liquid (sulfuric acid concentration 170g / L), and introduce sulfur dioxide gas for 4.2h for high acid reduction leaching, with a liquid-solid ratio of 5.3mL:1g, temperature 89°C, stirring leaching for 9h, and end point sulfuric acid concentration 76g / L, to obtain high acid leaching solution and high acid leaching residue, slurry the high acid leaching residue with high acid leaching solution, control the liquid-solid ratio to 2mL:1g, and obtain high acid germanium-rich ore pulp.

[0065] S4: adding concentrated sulfuric acid to the high-acid germanium-rich slurry obtained in S3 to adjust the acidity and perform ultra-high acid leaching, wherein the temperature is 92° C., the stirring leaching is carried out for 8 hours, the end point sulfuric acid concentration is 175 g / L, and ultra-high acid leaching liquid and ultra-high acid leaching residue are obtained after liquid-solid separation.

[0066] The experimental results show that after the zinc oxide fume is treated by the process of Example 3, the leaching rate of germanium in the ultra-high acid leaching solution (germanium-rich leaching solution) is 82.1%.

[0067] Example 4 A method for selectively leaching germanium from zinc oxide dust based on acidity gradient control

[0068] like Figure 1 As shown, the following steps are included:

[0069] S1: 132g of germanium-containing zinc oxide dust (0.0120% germanium) from a certain factory was ball-milled to a -200 mesh density of ≥87%. 500mL of hydrometallurgical electrolytic wastewater (sulfuric acid concentration: 185g / L) was then slowly added. The mixture was heated to 74°C and stirred for 4 hours, with the pH reaching 5.1 at the end of the reaction. After liquid-solid separation, the resulting intermediate leachate was returned to the main hydrometallurgical system for zinc recovery, and the intermediate leach residue was used for subsequent germanium enrichment.

[0070] S2: The intermediate leaching residue obtained in S1 was slurried with hydrometallurgical zinc electrolysis wastewater (sulfuric acid concentration 185g / L) at a liquid-solid ratio of 5.7mL:1g, temperature 79°C, and leaching for 8 hours, with an endpoint pH of 2.4. After liquid-solid separation, weak acid leaching solution and weak acid leaching residue were obtained.

[0071] S3: Take the weak acid leaching residue in S2, slurry it with wet zinc electrolysis waste liquid (sulfuric acid concentration 185g / L), and introduce sulfur dioxide gas for 3.8h for high acid reduction leaching, with a liquid-solid ratio of 5.1mL:1g, temperature 90℃, stirring and leaching for 9h, and the end point sulfuric acid concentration of 77g / L, to obtain high acid leaching solution and high acid leaching residue. The high acid leaching residue is slurried with high acid leaching solution, and the liquid-solid ratio is controlled to be 2.5mL:1g to obtain high acid germanium-rich ore pulp.

[0072] S4: Add concentrated sulfuric acid to the high-acid germanium-rich slurry obtained in S3 to adjust the acidity and perform ultra-high acid leaching at a temperature of 93°C and stirring for 8 hours. The end point sulfuric acid concentration is 178 g / L. After liquid-solid separation, ultra-high acid leaching liquid and ultra-high acid leaching residue are obtained.

[0073] The experimental results show that after the zinc oxide fume is treated by the process of Example 4, the leaching rate of germanium in the ultra-high acid leaching solution (germanium-rich leaching solution) is 81.8%.

[0074] Comparative Example 1: A method for leaching germanium from zinc oxide dust

[0075] The only difference from Example 1 is that in step S3, high-acid reduction leaching is not performed using sulfur dioxide gas.

[0076] The experimental results show that after zinc oxide dust is leached by neutral leaching, weak acid leaching, high acid leaching and ultra-high acid leaching, the leaching rate of germanium is 74.5%.

[0077] Comparative Example 2: A method for leaching germanium from zinc oxide dust

[0078] The only difference from Example 2 is that the neutral leaching residue obtained in step S1 is not subjected to weak acid leaching in S2 but directly enters the high acid leaching process in S3.

[0079] The experimental results show that after the zinc oxide dust is subjected to the traditional three-stage acid leaching of neutral leaching-high acid leaching-ultra-high acid leaching, the leaching rate of germanium is 62.6%.

[0080] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed. The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application. The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application. These improvements and variations should also be regarded as the scope of protection of the present application.

Claims

1. A method for selectively leaching germanium based on acidity gradient regulation, characterized in that: The following steps are involved: S1: neutral leaching of the germanium-containing raw material to obtain intermediate leaching solution and intermediate leaching residue; S2: subjecting the intermediate leaching residue to weak acid leaching to obtain weak acid leaching solution and weak acid leaching residue; S3: subjecting the weak acid leaching residue to high acid leaching, while introducing sulfur dioxide to enhance leaching, to obtain high acid leaching solution and high acid leaching residue; slurrying the high acid leaching residue with the high acid leaching solution to obtain high acid germanium-rich ore pulp; S4: subjecting the high-acid, germanium-rich slurry to ultra-high acid leaching to obtain ultra-high acid leaching solution and ultra-high acid leaching residue; wherein the germanium recovery rate in the ultra-high acid leaching solution is greater than 80%.

2. The method for selectively leaching germanium based on acidity gradient regulation according to claim 1, characterized in that: The germanium-containing raw material includes germanium-containing smoke and / or germanium-containing slag.

3. The method for selectively leaching germanium based on acidity gradient regulation according to claim 2, characterized in that: The germanium-containing raw material is zinc oxide fume, and the germanium content in the zinc oxide fume is 0.01%-0.1% by mass.

4. The method for selectively leaching germanium based on acidity gradient regulation according to any one of claims 1 to 3, characterized in that: In the method, the neutral leaching temperature is controlled to be less than the weak acid leaching temperature and less than the high acid leaching temperature.

5. The method for selectively leaching germanium based on acidity gradient control according to any one of claims 1 to 3, characterized in that: The neutral leaching in step S1 includes: using wet zinc smelting electrolytic waste liquid as a leaching agent, controlling the liquid-solid ratio to (3-5) mL:1 g, the temperature to 70° C. to 80° C., the time to 3 h to 5 h, and the endpoint pH to 5.0-6.

0.

6. The method for selectively leaching germanium based on acidity gradient control according to any one of claims 1 to 3, characterized in that: The weak acid leaching in step S2 includes: using wet zinc electrolysis waste liquid as a leaching agent, controlling the liquid-solid ratio to (4-6) mL:1 g, the temperature to 75° C. to 85° C., the time to 7 h to 9 h, and the end point pH to 2.0-3.

0.

7. The method for selectively leaching germanium based on acidity gradient control according to any one of claims 1 to 3, characterized in that: The high-acid leaching in step S3 includes: using wet zinc smelting electrolytic waste liquid as a leaching agent, controlling the liquid-solid ratio to (4-6) mL:1 g, the temperature to 80° C. to 90° C., the time to 8 h to 10 h, and the endpoint sulfuric acid concentration to 70 g / L to 90 g / L.

8. The method for selectively leaching germanium based on acidity gradient control according to claim 7, characterized in that: In step S3, sulfur dioxide is introduced simultaneously to enhance leaching, with 0.5 L to 1.0 L of sulfur dioxide introduced per liter of pulp per hour, and the sulfur dioxide introduction time is 3 hours to 5 hours.

9. The method for selectively leaching germanium based on acidity gradient control according to any one of claims 1 to 3, characterized in that: In step S3, the high-acid leaching residue is slurried with the high-acid leaching liquid, and the liquid-to-solid ratio of the high-acid leaching liquid to the high-acid leaching residue is controlled to be (2-3) mL:1 g.

10. The method for selectively leaching germanium based on acidity gradient control according to any one of claims 1 to 3, characterized in that: The ultra-high acid leaching in step S4 includes: adding concentrated sulfuric acid to the high-acid germanium-rich slurry to adjust the acidity, controlling the sulfuric acid concentration in the obtained ultra-high acid leaching solution to be 170g / L-190g / L, the temperature to be 90°C-93°C, and the time to be 8h-10h.

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