Method for gradient separation of zinc, germanium, indium and tin from zinc oxide smoke leachate

Abstract

The invention relates to a method for gradient separation of zinc, germanium, indium and tin from zinc oxide smoke dust leachate, and belongs to the technical field of hydrometallurgy, the method mainly comprises the four steps of extraction, stripping of zinc and tin through reverse extraction, zinc precipitation of raffinate phase oxalic acid and indium precipitation by adding ammonium sulphide, and the process can realize staged recovery of valuable metals in zinc oxide smoke dust, so that the recovery rate of the zinc oxide smoke dust is improved. The technological process is short, the cost is low, operation is easy, the high recovery rate of valuable metal in the zinc oxide smoke dust is achieved, the problems that Fe < 3 + > and In < 3 + > are difficult to separate, Fe < 3 + > is extracted by P204 and the like are solved, meanwhile, germanium and tin are separated out in advance, it is avoided that tannin is used for precipitating germanium, the purity of obtained strip liquor and leaching residues of sulfide precipitates is high, and the recovery rate of valuable metal in the zinc oxide smoke dust is high. The material can be directly used as a precursor of a silicon-based germanium tin optoelectronic material and an ITO (Indium Tin Oxide) film; and finally, the concentration of valuable metal and toxic metal in the residual liquid is reduced to milligram / upgrade, the residual liquid can be directly discharged, and the whole process is clean and efficient.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution. Background Art

[0002] Zinc is widely used in batteries, construction, automobiles, electronics, and healthcare. Zinc exists mainly in the form of lead-zinc sulfide ore in nature, and the hydrometallurgical zinc smelting process contributes about 85% of zinc production. In the process of producing zinc from zinc sulfide ore through hydrometallurgy and pyrometallurgy, a large amount of secondary resources are generated, such as zinc neutral leaching slag, zinc oxide fume, etc. These secondary resources usually contain a variety of valuable metals and toxic metals, such as: Zn, Ge, In, Sn, Ag, Pb, Fe, As, Cd, etc.

[0003] Germanium and indium are important rare earth metals, which are widely used in the production of semiconductors, electronic communications, photovoltaic materials, wireless radio frequency transmission equipment and other devices. Due to the strategic significance of germanium and indium resources and their irreplaceability in some special fields, they have been classified as major key minerals by many countries and their exports are strictly restricted. At present, no independent indium or germanium deposits have been found in nature. They are often associated with zinc ores (such as sphalerite) and are recovered as by-products. Tin exists mainly in the form of dioxide (cassiterite) and various sulfides (such as cassiterite) in nature. About 43.4% of the world's tin is used to make electronic solders, 15.5% of tin is used to make chemicals, and 14.7% of tin is used to make tinplate. However, in recent decades, with the adjustment of industrial structure and the increase in people's demand for high-end products, high-grade zinc and tin ores are facing the risk of exhaustion. Therefore, the resource utilization of zinc smelting secondary resources containing a large amount of valuable metals has always attracted people's attention. At present, the leaching solution containing zinc, germanium and indium is used as the raw material for the stepwise separation of valuable metals. Usually, P204 is used to extract and separate indium first, and then tannin germanium is used to precipitate germanium to obtain tannin germanium. Finally, the precipitated germanium is purified and impurities are removed by electrolysis to separate zinc. However, in the process of extracting indium with P204, due to Fe 3+ The valence state and In 3+ The two are the same, so both are easily extracted and stripped, and it is difficult to obtain effective separation. In the process of tannin germanium precipitation, due to the serious tannin flocculation between tannin and leachate, the kinetics of tannin germanium precipitation deteriorates, and filtration occurs from time to time. Impurities are wrapped by large molecular tannin precipitates, and conventional water washing is difficult to remove impurities in tannin germanium, resulting in a decrease in the grade of germanium concentrate. At the same time, the consumption of tannic acid is large, the cost is high, and emulsified tannin is produced in the neutralization and purification steps. Introducing emulsified tannin during the electrolysis process will burn the electrodes. In addition, tannin will also react with Sn 4+ Precipitation occurs, making the separation of germanium, indium and zinc difficult and inefficient. Summary of the invention

[0004] In order to overcome the problems existing in the background technology, the present invention provides a new method for efficiently and economically separating zinc, germanium, indium and tin from zinc oxide fume leaching solution. The method of the present invention not only realizes the comprehensive recovery of valuable metals in zinc oxide fume, but also solves the problem of Fe 3+ WithIn 3+ The problem of difficult separation is solved; and before zinc recovery, the separation of germanium and tin is achieved, thereby solving the problem that the existing process requires tannin to precipitate germanium and the problems caused by tannin precipitation of germanium. The leached residue of the stripping solution and sulfide precipitate obtained by the present invention has high purity and can be directly used as a precursor of silicon-based germanium-tin optoelectronic materials or ITO films; the concentration of valuable metals and toxic metals in the final residual liquid is reduced to mg / L level, which can be directly discharged, and the whole process is clean and efficient.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions: The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution comprises the following steps: (1) preparing an organic phase containing trioctylamine (TOA), tributyl phosphate (TBP) and sulfonated kerosene (SK); (2) taking zinc oxide fume leaching liquid as the aqueous phase, pouring the aqueous phase into a reactor containing an organic phase to extract germanium and tin; after the extraction is completed, separating the organic phase from the aqueous phase; (3) adding a sulfuric acid solution to the organic phase separated in step (2) to strip germanium and tin; (4) adding zinc oxalate to the aqueous phase separated in step (2) and filtering; (5) Add ammonium sulfide to the filtrate obtained in step (4) to precipitate indium.

[0006] Furthermore, in the organic phase of step (1), the volume ratio of trioctylamine TOA: tributyl phosphate TBP: sulfonated kerosene SK is 0.2-16:1:0-50; in step (2), the pH value of the aqueous phase is 1-2, and the volume ratio of the aqueous phase to the organic phase is 1-6:1.

[0007] Furthermore, the concentration of the sulfuric acid solution added in step (3) is 1-7M, and the volume ratio of the sulfuric acid solution to the organic phase is 1-5:1.

[0008] Furthermore, the stripping solution is used as a raw material for preparing silicon-based germanium-tin optoelectronic materials, and the organic phase after stripping is returned to step (2).

[0009] Furthermore, in step (4), the amount of solid oxalic acid added is 37.5-312.5 g / L, the zinc precipitation reaction is 5-60 min, and the reaction temperature is room temperature to 85°C.

[0010] Furthermore, in step (5), the pH of the filtrate does not need to be adjusted before adding ammonium sulfide. The added ammonium sulfide contains 14 wt % water, the amount of ammonium sulfide added is 0.025-0.375 mL / mL by volume with respect to the filtrate, the temperature for precipitating indium is room temperature, and the reaction time is 10-120 min.

[0011] Furthermore, after the indium is precipitated in step (5), the solid and liquid are separated, the filter residue is dried and then calcined in an oxygen-containing atmosphere, sulfuric acid solution is added to the calcined residue for neutral leaching, and indium and tin enter the residue, which can be used as a precursor for preparing an ITO film, and the leaching solution is returned to step (4) for zinc precipitation.

[0012] Furthermore, the neutral leaching endpoint pH value is 5-6.

[0013] Beneficial effects of the present invention: The method of the present invention can achieve high recovery of zinc, germanium, indium and tin in zinc oxide smoke, and the concentration of valuable metals and toxic metals in the final residual liquid is reduced to mg / L level, which can be directly discharged. The whole process is clean and efficient, and high-purity zinc oxalate, tin oxalate and indium oxide can be obtained, achieving the purpose of clean production and comprehensive utilization of resources.

[0014] The method of the invention has the characteristics of short process flow, low cost, simple and safe operation, and the final residual liquid will not pollute the environment.

[0015] The present invention does not use P204 as an extractant to extract indium, thereby avoiding the inhibition of P204 extraction by silicate. 3+ It will also be extracted by P204, making it difficult to separate iron and indium.

[0016] The method of the present invention realizes the separation of germanium and tin before zinc recovery, thereby solving the problem that tannin is needed to precipitate germanium in the existing process, and the problem that tannin flocculation is serious and the power of tannin precipitating germanium is poor in the process; at the same time, since tannin is not needed to precipitate germanium, the problem that emulsified tannin exists in the electrolyte after tannin precipitates germanium in the existing process and the emulsified tannin will burn the electrode in the electrolysis process is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0019] The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution comprises the following steps: (1) preparing an organic phase extractant with a volume ratio of trioctylamine TOA: tributyl phosphate TBP: sulfonated kerosene SK = 0.2-16:1:0-50; Because the present invention does not use P204 to extract In, in the process of TOA+TBP+SK extracting germanium and tin, Fe3+ will not compete with germanium and tin for extraction, thereby solving the problem of inhibiting P204 from extracting indium when silicate is used; and Fe3+ in the solution 3+ It will also be extracted by P204, making it difficult to separate iron and indium.

[0020] (2) Measure the zinc oxide fume leaching liquid as the aqueous phase, the pH value of the aqueous phase is 1-2, and the volume ratio of the aqueous phase to the organic phase is controlled to be 1-6:1. Pour the aqueous phase into a reactor filled with an organic extractant to extract germanium and tin; extract at room temperature for about 10 minutes. After the extraction is completed, separate the organic phase and the aqueous phase.

[0021] This step separates tin from germanium, avoiding the co-precipitation of zinc and tin in the subsequent zinc oxalate precipitation process, and high-purity zinc oxalate can be obtained.

[0022] (3) Adding sulfuric acid solution to the organic phase separated in step (2) to strip germanium and tin, the concentration of the added sulfuric acid solution is 1-7M, the volume ratio of the sulfuric acid solution to the organic phase is 1-5:1, and stripping is performed 2 to 3 times to strip germanium and tin from the organic phase.

[0023] (4) Add zinc oxalate to the aqueous phase separated in step (2) to obtain zinc oxalate precipitate, which is filtered; the amount of solid oxalic acid added is 37.5-312.5 g / L, the zinc precipitation reaction is carried out for 5-60 min, and the reaction temperature is room temperature to 85°C.

[0024] In this step, zinc is precipitated as high-purity zinc oxalate, indium is substantially not precipitated, and the concentrations of zinc and tin in the filtrate are further reduced.

[0025] (5) Without adjusting the pH value of the filtrate in step (4), ammonium sulfide is added to the filtrate to precipitate indium. The water content of the added ammonium sulfide is 14 wt%, and the volume ratio of the added ammonium sulfide to the filtrate is 0.025-0.375 mL / mL. The temperature for precipitating indium is room temperature, and the reaction time is 10-120 min. After precipitation of indium, the solid and liquid are separated, and the filter residue is placed in a drying oven for drying.

[0026] During the indium precipitation process, the residual zinc, tin and indium in the filtrate will precipitate together and generate sulfur.

[0027] (6) The dried filter residue in step (5) is calcined in an air atmosphere in a muffle furnace with the furnace mouth open. After calcination, sulfuric acid solution is added for neutral leaching at a leaching pH of 5-6. After leaching, the leached residue containing indium and tin is obtained by filtering. The leaching solution is returned to step (4) for zinc precipitation.

[0028] By roasting in the presence of oxygen, sulfur is converted into sulfur dioxide gas, and the generated zinc sulfide, tin sulfide and indium sulfide are converted into oxides. Then, based on the low solubility of indium oxide at low temperature and low acid, the precipitate is neutrally leached with sulfuric acid solution at low temperature (can be completed at room temperature), which causes zinc oxide to dissolve, while indium and tin oxides remain in the slag phase.

[0029] The stripping solution of step (3) can be directly used as a raw material for preparing the ITO film, and the organic phase is returned to step (2).

[0030] In order to more clearly illustrate the present invention, it is described in detail through the following examples.

[0031] The main components of the zinc oxide smoke leaching solution used in the following examples are: Example 1

[0032] The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution comprises the following steps: (1) The extractant (organic phase) was prepared at a volume ratio of TOA:TBP:SK = 31.5:7.5:61, and then 80 mL of zinc oxide fume leaching solution was measured as the aqueous phase. The aqueous phase was added to the extractant at a volume ratio of A (aqueous phase): O (organic phase) = 1.45:1. At room temperature, a mechanical oscillator was used to start the extraction of germanium and tin. The extraction reaction was stopped after 10 min, and the organic phase was separated from the aqueous phase using a separatory funnel. The organic phase was back-extracted 3 times with a 4 M sulfuric acid solution to strip the germanium and tin from the organic phase by back-extraction. The contents of germanium and tin in the back-extracted solution were 64.57 mg / L and 1.49 g / L, respectively, according to ICP analysis.

[0033] (2) The raffinate (water phase after separation) of step (1) was placed in a conical flask. Solid oxalic acid was added to the conical flask containing the raffinate at room temperature in an amount of 187.5 g / L, and the reaction was carried out for 5 minutes to precipitate and separate zinc. After the precipitation reaction was completed, the mixture was filtered and separated to obtain a filter residue and a filtrate. The filter residue was placed in a drying oven at 50°C for 10 hours. According to ICP analysis, the zinc content in the filtrate was 330.05 mg / L.

[0034] (3) The filtrate obtained in step (2) is placed in a conical flask, and then, at room temperature, an ammonium sulfide solution (unless otherwise specified, all ammonium sulfide solutions used are ammonium sulfide solutions containing 14 wt% water) is added to the conical flask containing the filtrate at a volume ratio of 0.1875 mL / mL to precipitate indium. The precipitation reaction is terminated after 60 min of reaction, and the mixture is filtered to separate and obtain a filtrate and a filter residue.

[0035] Valuable metal concentration in the filtrate:

[0036] The indium content in the mixed solution was 0.40 mg / L by ICP analysis. The extraction rates of zinc, germanium, indium and tin were calculated to be 99.54%, 95.27%, 99.42% and 95.63% respectively, and the stripping rates of germanium and tin were 96.63% and 91.52% respectively. The filter residue was placed in a drying oven at 50°C for 10 hours, and then the dried filter residue was placed in a muffle furnace and calcined in an air atmosphere. After the calcination was completed, the furnace temperature was lowered to room temperature, and the calcined residue was taken out for analysis. The In content in the calcined residue was measured to be 11wt%.

[0037] (4) The calcined residue obtained in step (3) is placed in a flask, and then a sulfuric acid solution is added at room temperature with a liquid-to-solid ratio of 4:1 for neutral leaching. The pH of the leaching end point is controlled to be 5-6. The leaching reaction is terminated after 90 minutes of reaction, and the residue is filtered to obtain a filter residue and a filtrate. The filtrate is returned to step (2), and the filter residue is placed in a drying oven at 50° C. for 10 hours. According to ICP analysis, the contents of indium and tin in the filter residue are 39.69wt% and 37.58wt% (dry basis), respectively. Example 2

[0038] The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution comprises the following steps: (1) The extractant (organic phase) was prepared at a volume ratio of TOA:TBP:SK = 31.5:7.5:61, and then 80 mL of zinc oxide fume leaching solution was measured as the aqueous phase. The aqueous phase was quickly poured into the reactor containing the organic phase at a volume ratio of A (aqueous phase): O (organic phase) = 4:1. At room temperature, a mechanical oscillator was used to start the extraction of germanium and tin. The extraction reaction was stopped after 10 min, and the organic phase was separated from the aqueous phase by a separatory funnel. The organic phase was stripped once with a 4 M sulfuric acid solution to remove germanium and tin from the organic phase. The contents of germanium and tin in the stripping solution were 141.54 mg / L and 3.02 g / L, respectively, according to ICP analysis.

[0039] (2) The raffinate (water phase after separation) of step (1) was placed in a conical flask, and then solid oxalic acid was added to the conical flask containing the raffinate at room temperature in an amount of 125 g / L for 5 min to precipitate zinc. After the precipitation reaction was completed, the residue was filtered and separated to obtain a filtrate. The zinc content in the filtrate was 5.15 g / L by ICP analysis, and the residue was placed in a drying oven at 50°C and kept dry for 10 h.

[0040] (3) The filtrate obtained in step (2) was placed in a conical flask, and then, at room temperature, an ammonium sulfide solution was added to the conical flask containing the filtrate at a volume ratio of 0.1875 mL / mL to precipitate indium. The precipitation reaction was terminated after 60 minutes of reaction, and the residue and the filtrate were separated by filtration. The indium content in the filtrate was 0.47 mg / L by ICP analysis, and the residue was placed in a drying oven at 50°C and kept dry for 10 hours.

[0041] The dried filter residue was placed in a muffle furnace with the furnace mouth opened and calcined in an air atmosphere. After the calcination was completed, the furnace temperature was lowered to room temperature, and the calcined residue was taken out for analysis. The In content in the calcined residue was measured to be 0.04%.

[0042] (4) The calcined slag obtained in step (3) is placed in a flask, and then a sulfuric acid solution is added at a liquid-to-solid ratio of 3:1 at room temperature to neutrally leach the calcined slag, and the reaction end point pH is controlled to be 5.5. The leaching reaction is terminated after the reaction for 120 minutes, and the mixture is filtered to separate to obtain a filter residue and a filtrate. The contents of indium and tin in the filter residue are 2.36 wt% and 60.29 wt% (dry basis), respectively, according to ICP analysis. The filtrate is returned to step (2).

[0043] The extraction rates of germanium and tin were 70.82% and 68.87% respectively (the amount of germanium and tin finally entering the stripping solution accounted for the total amount of germanium and tin in the zinc oxide smoke leaching solution, the same as in the following examples), and the stripping rates of germanium and tin were 70.20% and 61.29% respectively (the percentage of germanium and tin stripped from the organic phase by stripping, the same as in the following examples). The extraction rate of zinc was 93.41% (the amount of zinc in the filtrate after entering the indium precipitation accounted for the total amount of zinc in the zinc oxide smoke leaching solution, the same as in the following examples), and the extraction rate of indium was 95.63% (the amount of indium in the filtrate after entering the zinc precipitation accounted for the total amount of indium in the zinc oxide smoke leaching solution, the same as in the following examples). Example 3

[0044] The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution comprises the following steps: (1) Prepare the extractant (organic phase) at a volume ratio of TOA:TBP:SK=31.5:7.5:61, then take 80mL of zinc oxide fume leaching solution as the aqueous phase, and quickly pour the aqueous phase into the reactor containing the organic phase at a volume ratio of A (aqueous phase):O (organic phase)=2:1. Use a mechanical oscillator to start extracting germanium and tin at room temperature. Stop the extraction reaction after 60 minutes, and separate the organic phase from the aqueous phase using a separatory funnel. Use 4 M sulfuric acid solution to strip the organic phase three times to strip germanium and tin from the organic phase. ICP analysis shows that the contents of germanium and tin in the stripping solution are 61.57 mg / L and 1.33 g / L, respectively.

[0045] (2) The raffinate from step (1) was placed in a conical flask, and then 250 g / L of oxalic acid solid was added to the raffinate at room temperature for 40 min to precipitate and separate zinc. After the precipitation reaction was completed, the residue and the filtrate were separated by filtration. The zinc content in the filtrate was 240.76 mg / L by ICP analysis. The residue was placed in a drying oven at 50°C and kept dry for 10 h.

[0046] (3) The filtrate obtained in step (2) was placed in a conical flask, and then at room temperature, 0.375 mL / mL of ammonium sulfide solution was added to the conical flask containing the filtrate to precipitate indium. The precipitation reaction was terminated after 20 minutes of reaction, the mixture was filtered and separated, and the filter residue was placed in a drying oven at 50°C for 10 hours. The indium content in the mixed solution was 38.1 mg / L by ICP analysis. The dried filter residue was then placed in a muffle furnace and calcined in an air atmosphere. The calcination experiment was terminated after a certain reaction time. When the furnace temperature dropped to room temperature, the calcined residue was taken out for analysis. At this time, the In content in the calcined residue was 1.43%.

[0047] It was calculated that the extraction rates of zinc, germanium, indium and tin were 99.65%, 90.13%, 75.25% and 89.87% respectively, and the stripping rates of germanium and tin were 94.63% and 88.52% respectively. Example 4

[0048] The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution comprises the following steps: (1) The extractant (organic phase) was prepared at a volume ratio of TOA:TBP:SK = 20:5:75, and then 80 mL of zinc oxide fume leaching solution was measured as the aqueous phase. The aqueous phase was quickly poured into the reactor containing the organic phase at a volume ratio of A (aqueous phase): O (organic phase) = 1.45:1. At room temperature, the mechanical oscillator was turned on to start the extraction of germanium and tin. The extraction reaction was stopped after 10 min, and the organic phase was separated from the aqueous phase by a separatory funnel. The organic phase was stripped 3 times with 4 M sulfuric acid solution to achieve the purpose of stripping germanium and tin from the organic phase. The contents of germanium and tin in the stripping solution were 62.08 mg / L and 1.37 g / L, respectively, according to ICP analysis.

[0049] (2) The raffinate from step (1) was placed in a conical flask, and then 187.5 g / L of oxalic acid solid was added to the conical flask containing the raffinate at room temperature for 30 min to precipitate and separate zinc. After the precipitation reaction was completed, the mixture was filtered to separate the filtrate and the residue. The zinc content in the mixed solution was 310.77 mg / L by ICP analysis. The residue was placed in a drying oven at 50°C and kept dry for 10 h.

[0050] (3) The filtrate obtained in step (2) is placed in a conical flask, and then at room temperature, ammonium sulfide solution is added to the filtrate at a volume ratio of 0.25 mL / mL to precipitate indium. After reacting for 100 min, the mixture is filtered to obtain a filtrate and a residue.

[0051] The indium content in the filtrate was 29.9 mg / L by ICP analysis. The filter residue was placed in a drying oven at 50°C for 10 hours, and the dried filter residue was placed in a muffle furnace and calcined in an air atmosphere. After the calcination, the furnace temperature was lowered to room temperature, and the calcined residue was taken out for analysis, and the In content in the calcined residue was measured to be 4.74%.

[0052] It was calculated that the extraction rates of zinc, germanium, indium and tin were 99.66%, 93.74%, 86.84% and 92.13% respectively, and the stripping rates of germanium and tin were 94.54% and 90.79% respectively. Example 5

[0053] The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution comprises the following steps: (1) Prepare the extractant (organic phase) at a volume ratio of TOA:TBP:SK=31.5:7.5:61, then take 80 mL of zinc oxide fume leaching solution as the aqueous phase, and quickly pour the aqueous phase into the reactor containing the organic phase at a volume ratio of A (aqueous phase):O (organic phase)=1.45:1. Use a mechanical oscillator to start extracting germanium and tin at room temperature. Stop the extraction reaction after 5 minutes, and separate the organic phase from the aqueous phase using a separatory funnel.

[0054] The organic phase was stripped once with 3 M sulfuric acid solution to achieve the purpose of stripping germanium and tin from the organic phase. ICP analysis showed that the contents of germanium and tin in the stripping solution were 112.88 mg / L and 2.44 g / L, respectively.

[0055] (2) The raffinate (aqueous phase) of step (1) was placed in a conical flask, and then 187.5 g / L of oxalic acid solid was added to the conical flask containing the raffinate at room temperature for 5 min to precipitate and separate zinc. After the precipitation reaction was completed, the filtrate and the filter residue were separated by filtration. The zinc content in the filtrate was 330.05 mg / L by ICP analysis. The filter residue was placed in a drying oven at 50°C for 10 h.

[0056] (3) The filtrate obtained in step (2) was placed in a conical flask, and then at room temperature, an ammonium sulfide solution was added to the filtrate at a volume ratio of 0.1875 mL / mL to precipitate indium. The reaction was continued for 40 minutes, and the filtrate and the residue were separated by filtration. The indium content in the filtrate was 6.01 mg / L by ICP analysis.

[0057] The filter residue was placed in a drying oven at 50°C for 10 hours, and the dried filter residue was placed in a muffle furnace and calcined in an air atmosphere. After the calcination was completed, the furnace temperature was lowered to room temperature, and the calcined residue was taken out for analysis, and the In content in the calcined residue was 7.44%.

[0058] The extraction rates of zinc, germanium, indium and tin were calculated to be 99.54%, 95.27%, 91.08% and 95.63% respectively, and the stripping rates of germanium and tin were 56.09% and 50.13% respectively.

[0059] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution, characterized in that: The following steps are involved: (1) preparing an organic phase containing trioctylamine (TOA), tributyl phosphate (TBP) and sulfonated kerosene (SK); (2) taking zinc oxide fume leaching liquid as the aqueous phase, pouring the aqueous phase into a reactor containing an organic phase to extract germanium and tin; After the extraction is completed, the organic phase and the aqueous phase are separated; (3) adding a sulfuric acid solution to the organic phase separated in step (2) to strip germanium and tin; (4) adding zinc oxalate to the aqueous phase separated in step (2) and filtering; (5) Add ammonium sulfide to the filtrate obtained in step (4) to precipitate indium.

2. The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution according to claim 1, characterized in that: In the organic phase of step (1), the volume ratio of trioctylamine TOA: tributyl phosphate TBP: sulfonated kerosene SK is 0.2-16:1:0-50; in step (2), the pH value of the aqueous phase is 1-2, and the volume ratio of the aqueous phase to the organic phase is 1-6:

1.

3. The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution according to claim 1 or 2, characterized in that: The concentration of the sulfuric acid solution added in step (3) is 1-7M, and the volume ratio of the sulfuric acid solution to the organic phase is 1-5:

1.

4. The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution according to claim 3, characterized in that: The stripping solution is used as a raw material for preparing silicon-based germanium-tin optoelectronic materials, and the organic phase after stripping is returned to step (2).

5. The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution according to claim 3, characterized in that: In step (4), the amount of solid oxalic acid added is 37.5-312.5 g / L, the zinc precipitation reaction is 5-60 min, and the reaction temperature is room temperature to 85°C.

6. The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution according to claim 3, characterized in that: In step (5), the pH of the filtrate does not need to be adjusted before adding ammonium sulfide. The added ammonium sulfide contains 14 wt % water, and the volume ratio of ammonium sulfide added to the filtrate is 0.025-0.375 mL / mL. The temperature for precipitating indium is room temperature, and the reaction time is 10-120 min.

7. The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution according to any one of claims 4 to 6, characterized in that: After the indium is precipitated in step (5), the solid and liquid are separated, the filter residue is dried and then roasted in an oxygen-containing atmosphere, sulfuric acid solution is added to the roasted residue for neutral leaching, and indium and tin enter the residue, which can be used as a precursor for preparing an ITO film. The leaching solution is returned to step (4) for zinc precipitation.

8. The method for stepwise separation of zinc, germanium, indium and tin from zinc oxide fume leaching solution according to claim 7, characterized in that: The neutral leaching endpoint pH is 5-6.

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