Method for purifying and removing impurities from indium electrolyte by taking fresh sponge indium as raw material
Through the purification and removal method of fresh sponge indium, the problem of removing impurities in indium electrolyte is solved, and efficient and environmentally friendly indium electrolyte purification is achieved, and refined indium products that meet the standards are produced, reducing production costs and environmental risks.
Patent Information
- Application Number
- CN202510508479.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-22
- Publication Date
- 2025-08-08
AI Technical Summary
In the purification of indium electrolyte, the problems of poor resin selectivity, organic phase contamination, zinc residue and indium loss are difficult to effectively remove impurities such as Pb, Sn, Cd, T1, etc., resulting in the electrolyte not meeting the purity requirements of refined indium.
Fresh sponge indium is used as the purification material, and through zinc ingot replacement, ultrasonic activation and sulfuric acid treatment, combined with ultrasonic assisted purification, the purification and impurity removal of indium electrolyte is achieved, including the preparation, activation and purification and decontamination steps of sponge indium, control parameters such as temperature, time and acidity, and use the reducing and adsorption properties of sponge indium to remove impurities.
It has achieved efficient purification of indium electrolyte, reduced dependence on external chemical reagents, recycled resources, and in line with the development trend of green metallurgy, and produced refined indium products that meet the purity of In99995 grade.
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Figure CN120443263A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of indium metallurgy and purification, and in particular to a method for purifying and removing impurities from indium electrolyte by using fresh sponge indium as a raw material. Background Art
[0002] As the application of the rare earth metal indium expands, its consumption is increasing, and product purity requirements are constantly rising. Electrolytic refining is a commonly used method for indium metallurgy and purification. During the electrolytic refining process to produce refined or high-purity indium, impurities such as Pb, Sn, Cd, and Tl from the anode enter the electrolyte as the electrolysis proceeds. Tin, which has a more positive potential than indium, is a difficult impurity to remove during indium electrorefining. When its concentration in the electrolyte reaches 10 mg / L, the indium deposited at the cathode does not meet the standard requirements for refined indium. Therefore, to produce qualified and stable products, regular purification of the indium electrolyte to remove impurities such as Pb, Sn, Cd, and Tl is essential.
[0003] Traditional methods for purifying indium electrolytes usually use ion exchange, solvent extraction, or single replacement reaction. Among them, ion exchange has problems such as poor resin selectivity and high resin regeneration cost; solvent extraction has problems such as organic phase contamination and difficult phase separation; single replacement reactions such as zinc powder replacement have problems such as zinc residue and indium loss.
[0004] Therefore, there is an urgent need for an economical and efficient treatment method with a high removal rate of impurities such as Pb, Sn, Cd, and Tl in indium electrolyte. Summary of the Invention
[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.
[0006] To this end, the present invention provides a method for purifying and removing impurities from indium electrolyte using fresh sponge indium as a raw material. The method is used to purify and remove impurities from indium electrolyte with excessive impurity content during the process of preparing refined indium by electrolytic refining of crude indium, and comprises the following steps:
[0007] Preparation of sponge indium: adding a reducing agent, zinc ingot, to the indium electrolyte with excessive impurity content to replace indium, thereby obtaining fresh sponge indium;
[0008] Activating the indium sponge: activating the fresh indium sponge with ultrasound to obtain activated indium sponge;
[0009] Purification and impurity removal: adding sulfuric acid to the indium electrolyte with excessive impurity content to control the sulfuric acid content to 20 g / L-70 g / L, then adding the activated sponge indium to purify and remove impurities, and filtering to obtain a qualified indium electrolyte;
[0010] Among them, the qualified indium electrolyte composition indicators include: In ions: 40g / L-100g / L, Cl ions: 25g / L-72g / L, Cd ions ≤1.0g / L, Sn ions ≤0.01g / L, Pb ions ≤0.01g / L, Zn ions <3g / L, Bi ions ≤0.005g / L, Tl ions ≤0.001g / L.
[0011] Furthermore, in the preparation of the sponge indium, the indium replacement temperature is 65° C.-96° C., the indium replacement time is 5 h-8 h, and the indium replacement endpoint pH is 3.2-4.5.
[0012] Furthermore, in the activation of the sponge indium, the activation temperature is 65° C.-85° C., the activation time is 30 min-120 min, and the activation pH is 2.5-3.8.
[0013] Furthermore, the activation is performed using ultrasound, and the power of the ultrasound is 75W-120W.
[0014] Furthermore, in the purification and impurity removal, the amount of the activated sponge indium added is 40g-80g per liter of the indium electrolyte with excessive impurity content, the purification and impurity removal temperature is 55°C-90°C, and the purification and impurity removal time is 120min-360min.
[0015] Furthermore, the purification and impurity removal is carried out under ultrasonic conditions, and the power of the ultrasonic waves is 60W-80W.
[0016] Furthermore, in the electrolytic refining of the crude indium, the composition of the anode crude indium satisfies In≥95.20%, Sn≤0.65%, Cd≤0.18%, Cu≤0.12% and Pb≤0.16%.
[0017] The method for purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material provided by the present invention has at least the following beneficial effects compared to the prior art:
[0018] (1) Self-circulation of raw materials: The sponge indium produced by the indium electrolyte is directly used as the purification material, realizing the closed-loop utilization of resources within the production system; the qualified indium electrolyte after purification is electrolytically purified according to the process conditions of conventional electrolytic refining of crude indium, and the final refined indium product meets the chemical composition requirements of In99995 refined indium (i.e., 99.995% purity) in YS / T 257-2009 "Indium".
[0019] (2) Process sustainability: significantly reducing dependence on external chemical reagents, reducing raw material costs and environmental risks;
[0020] (3) Green and environmentally friendly characteristics: No harmful substances are added during the entire purification process, which is in line with the current development trend of green metallurgy;
[0021] (4) Economical and efficient: Through internal resource recycling, the economy and resource utilization of the overall process are improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a process flow chart of the principle of purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material provided in the embodiment of the present application. 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 purifying and removing impurities from an indium electrolyte using fresh sponge indium as a raw material. The method is used to purify and remove impurities from an indium electrolyte with an excessive impurity content during the process of preparing refined indium by electrolytic refining of crude indium, and comprises the following steps:
[0025] Preparation of sponge indium: Add zinc ingot, a reducing agent, to an indium electrolyte with excessive impurity content to replace indium and obtain fresh sponge indium;
[0026] Sponge indium activation: fresh sponge indium is activated by ultrasonic wave to obtain activated sponge indium;
[0027] Purification and impurity removal: add sulfuric acid to the indium electrolyte with excessive impurity content to control the sulfuric acid content to 20g / L-70g / L, then add activated sponge indium to purify and remove impurities, and filter to obtain qualified indium electrolyte;
[0028] Among them, the qualified indium electrolyte composition indicators include: In ions: 40g / L-100g / L, Cl ions: 25g / L-72g / L, Cd ions ≤1.0g / L, Sn ions ≤0.01g / L, Pb ions ≤0.01g / L, Zn ions <3g / L, Bi ions ≤0.005g / L, Tl ions ≤0.001g / L, and pH 1.5-2.5.
[0029] In the embodiment of the present invention, zinc ingots are used as a reducing agent in the preparation of sponge indium, which optimizes the generation efficiency and initial purity of sponge indium. At the same time, the use of zinc ingots as a reducing agent can avoid the inclusion of broken zinc flakes, ensure the purity of sponge indium, ensure the stability of the indium content in the subsequent indium electrolyte, and avoid the introduction of impurity zinc. In the activation of sponge indium, fresh sponge indium is added to deionized water and activated with ultrasound to obtain a porous structure with lower impurity content and an activated sponge indium with a high specific surface area; the microstructure of sponge indium (such as porosity and high specific surface area) is regulated by the cavitation effect of ultrasound, which significantly enhances its subsequent adsorption and replacement capabilities; at the same time, the impurity content is effectively reduced by ultrasonic activation. The activated sponge indium is combined with sulfuric acid concentration control (20g / L-70g / L) to remove impurities (such as Cd, Sn, Pb, etc.) by utilizing the dual functions of reducing and adsorbing properties of sponge indium.
[0030] It is understandable that when the sulfuric acid concentration is lower than 20 g / L, impurity ions such as tin, bismuth, lead and thallium are not activated in place, the replacement reaction is slow or no replacement reaction is performed, and the purified liquid does not meet the indium electrolyte composition index; when the sulfuric acid concentration is higher than 70 g / L, impurity ions such as tin, bismuth, lead and thallium are fully activated, and the impurity ions in the purified indium electrolyte meet the indium electrolyte composition index, but the higher the sulfuric acid concentration, the more sponge indium or alkali is required to neutralize the excess acid, which increases the production cost. More importantly, other impurities will be introduced into the indium electrolyte, such as flake alkali, which also contains some impurities. For example, the preparation of sponge indium requires zinc flakes to be replaced with sponge indium, and sponge indium will also carry impurity ions such as zinc. Therefore, in order to control the increase of other impurities and reduce production costs, the sulfuric acid concentration is selected to be controlled at 20 g / L-70 g / L.
[0031] The chemical equation of the purification reaction principle is as follows:
[0032] 2In+3Sn 2+ =3Sn+2In 3+
[0033] 4In+3Sn 4+ =3Sn+4In 3+
[0034] 2In+3Pb 2+ =3Pb+2In 3+
[0035] In+Bi 3+ =Bi+In 3+
[0036] In+3Tl + =3Tl+In 3+
[0037] At the same time, impurities in the indium electrolyte and the replaced metals are adsorbed by the sponge indium, and the indium electrolyte is further purified, thereby improving the quality of the precipitated indium.
[0038] In a feasible embodiment, in the preparation of sponge indium, the indium replacement temperature is 65° C.-96° C., the indium replacement time is 5 h-8 h, and the indium replacement endpoint pH is 3.2-4.5.
[0039] Specifically, the indium replacement temperature is lower than 65°C. If the temperature is too low, the reaction rate is slow, the sponge indium activity is weak, and the indium in the indium electrolyte is difficult to be completely replaced, resulting in the loss of indium; the indium replacement temperature is higher than 96°C. If the temperature is too high, the pH value of the indium replacement end point is difficult to control, and the sponge indium is also easily oxidized into indium oxide, thereby losing its activity; under the condition of fixed temperature, the replacement time is too short, the indium replacement is incomplete, resulting in the loss of indium; if the time is too long, the sponge indium is easily oxidized into indium oxide and loses its activity, and the purification effect of the inactive sponge indium deteriorates, so the indium replacement time is controlled to 5h-8h; under the conditions of fixed temperature and time, when the pH is less than 3.2, the indium replacement is incomplete, resulting in the loss of indium; when the pH is greater than 4.5, zinc ions may hydrolyze into the sponge indium, increase the impurities of the sponge indium, and block the pore size of the sponge indium, resulting in reduced adsorption and ultimately poor purification effect; compared with the traditional replacement method, the refined design of the parameter range improves the consistency of the product.
[0040] In a feasible embodiment, during the activation of sponge indium, the activation temperature is 65° C.-85° C., the activation time is 30 min-120 min, and the activation pH is 2.5-3.8.
[0041] Specifically, when the pH is less than 2.5, sponge indium will react with acid, resulting in the loss of indium. When the pH is greater than 3.8, the resulting precipitates such as indium hydroxide will not dissolve, or new indium hydroxide precipitates will be generated, blocking the porosity of the sponge indium. When the activation temperature is lower than 65°C, the indium oxide precipitates attached to the sponge indium cannot be completely dissolved. At the same time, the impurities such as lead, bismuth and thallium attached to the sponge indium during the preparation of sponge indium cannot be separated and removed from the sponge indium, resulting in impurities being introduced during subsequent purification, resulting in incomplete purification. When the activation temperature is higher than 85°C, there may be problems such as oxidation loss of indium and redissolution of impurities, resulting in incomplete purification. If the activation time is shorter than 30 minutes, the porosity of the sponge indium does not meet the requirements and the specific surface area is insufficient. If the activation time is longer than 120 minutes, the sponge indium will be oxidized, resulting in indium loss.
[0042] Optionally, ultrasound is used for activation, and the power of the ultrasound is 75W-120W.
[0043] Specifically, if the ultrasonic power is too low, impurities attached to the indium sponge are difficult to separate from the indium sponge, slowing the dissolution of indium hydroxide and resulting in insufficient porosity and specific surface area. If the ultrasonic power is too high, impurity ions attached to large pores enter small pores, making separation from the indium sponge difficult and resulting in inadequate purification of the subsequent indium electrolyte. Therefore, the ultrasonic power is controlled at 75W-120W for activation.
[0044] In a feasible embodiment, during purification and impurity removal, the amount of activated sponge indium added is 40g-80g per liter of indium electrolyte with excessive impurity content, the purification and impurity removal temperature is 55°C-90°C, and the purification and impurity removal time is 120min-360min.
[0045] Specifically, the amount of activated sponge indium added is too low, less than 40g / L, resulting in insufficient active sites, incomplete adsorption of impurities, and the situation where impurities still exceed the standard after purification. The amount of activated sponge indium added is too high, greater than 80g / L. Under acidic conditions, the excess sponge indium may dissolve itself, increasing the loss of indium. The purification and impurity removal temperature is too low (<55°C), and impurities may not be completely removed. The purification and impurity removal temperature is too high (>90°C), and the oxidation of sponge indium is aggravated, losing its purification activity. The purification and impurity removal time is 120min-360min, which ensures that the impurities are thoroughly purified and balances efficiency and energy consumption.
[0046] Optionally, the purification and impurity removal is carried out under ultrasonic conditions, and the power of the ultrasonic waves is 60W-80W.
[0047] Specifically, the purification and impurity removal strategy of multiple mechanisms, namely reduction + adsorption + ultrasonic enhancement, was used to effectively purify and remove impurities from indium electrolyte with excessive impurity content, and a qualified indium electrolyte was obtained. By introducing ultrasonic assisted purification, mass transfer was enhanced through the cavitation effect, thereby improving purification efficiency. When the ultrasonic power is too low, below 60W, tin, lead, bismuth and thallium are insufficiently activated, the replacement is not thorough, and the purification is incomplete, making it difficult to meet the standards of indium electrolyte. At the same time, the impurities replaced cannot adhere to the surface of sponge indium, and a galvanic cell reaction cannot be formed. Inactive impurities will also dissolve again under this condition, resulting in incomplete purification. When the ultrasonic power is too high, exceeding 80W, although the impurities are highly active and are quickly replaced by sponge indium, the impurities attached to the sponge indium are easily dispersed, and lose their adhesion to the sponge indium, thus losing the galvanic cell effect. As a result, the less active impurities cannot be protected, and the impurities dissolve again, resulting in incomplete purification of the solution.
[0048] In a feasible embodiment, the crude indium is electrolytically refined, and the composition of the anode crude indium satisfies In≥95.20%, Sn≤0.65%, Cd≤0.18%, Cu≤0.12% and Pb≤0.16%.
[0049] Example 1
[0050] For crude indium with a content of In 98.25%, Sn 0.41%, Cd 0.13%, Cu 0.08%, and Pb 0.14%, electrolytic refining is used to prepare 99.995% refined indium. After a period of electrolysis, the ion content in the indium electrolyte is as follows: the mass-volume concentrations of In, Cl, Cd, Sn, Pb, Bi, Tl, and Zn are 88g / L, 29g / L, 0.75g / L, 0.107g / L, 0.056g / L, 0.009g / L, 0.006g / L, and 1.63g / L, respectively. The pH is 2.2. At this time, the impurity content in the indium electrolyte exceeds the standard and needs to be purified and removed. Figure 1 The process includes the following steps:
[0051] The first step is to prepare sponge indium: take the above-mentioned indium electrolyte with excessive impurity content and add zinc ingot, with indium replacement temperature T = 65°C, replacement time t = 8h, and end point pH = 4.5 to obtain fresh sponge indium.
[0052] The second step is sponge indium activation: the fresh sponge indium is added to deionized water and activated with ultrasound at a power of 75W. The sponge indium activation pH is 2.5, the activation time is t=30min, and the activation temperature is T=85°C to obtain an activated sponge indium with a porous structure having a lower impurity content and a high specific surface area.
[0053] The third step is purification and impurity removal: add sulfuric acid to the indium electrolyte with excessive impurity content after preparing the fresh sponge indium as mentioned above and control the acidity to 20 g / L, turn on the ultrasonic wave and control the power to 60 W, then add 80 g of activated sponge indium per liter of indium electrolyte for reduction and adsorption purification, the purification and impurity removal temperature T = 90 ° C, the purification and impurity removal time t = 120 min, and filter to obtain the purified indium electrolyte (qualified indium electrolyte) as shown in Table 1 below.
[0054] According to the crude indium electrolysis process conditions, crude indium purification electrolysis is carried out in the purified indium electrolyte, and the precipitated indium obtained meets the chemical composition table of In99995 refined indium "YS / T 257-2009 "Indium"".
[0055] Table 1 Indium and impurity content of indium electrolyte sponge before and after purification
[0056]
[0057] Example 2
[0058] For crude indium with a content of In 99.16%, Sn 0.53%, Cd 0.12%, Cu 0.09%, and Pb 0.12%, electrolytic refining is used to prepare 99.995% refined indium. After a period of electrolysis, the ion content in the indium electrolyte is as follows: the mass-volume concentrations of In, Cl, Cd, Sn, Pb, Bi, Tl, and Zn are 95g / L, 70g / L, 0.63g / L, 0.063g / L, 0.084g / L, 0.008g / L, 0.007g / L, and 1.95g / L, respectively. The pH is 2.3. At this time, the impurity content in the indium electrolyte exceeds the standard and needs to be purified and removed. Figure 1 The process includes the following steps:
[0059] The first step is to prepare sponge indium: take the above-mentioned indium electrolyte with excessive impurity content and add zinc ingot, indium replacement temperature T = 96 ° C, replacement time t = 5h, end point pH = 3.2, and obtain fresh sponge indium.
[0060] The second step is sponge indium activation: the fresh sponge indium is added to deionized water and activated with ultrasound at a power of 120W. The sponge indium activation pH is 3.8, the activation time is t=120min, and the activation temperature is T=65°C to obtain an activated sponge indium with a porous structure having a lower impurity content and a high specific surface area.
[0061] The third step is purification and impurity removal: add sulfuric acid to the indium electrolyte with excessive impurity content after preparing the fresh sponge indium as mentioned above and control the acidity to 70g / L, turn on the ultrasonic wave and control the power to 80W, then add 40g of activated sponge indium per liter of indium electrolyte for reduction and adsorption purification, the purification and impurity removal temperature T = 55°C, the purification and impurity removal time t = 360min, and filter to obtain the purified indium electrolyte (qualified indium electrolyte) as shown in Table 2 below.
[0062] According to the crude indium electrolysis process conditions, crude indium purification electrolysis is carried out in the purified indium electrolyte, and the precipitated indium obtained meets the chemical composition table of In99995 refined indium "YS / T 257-2009 "Indium"".
[0063] Table 2 Indium and impurity content of indium electrolyte sponge before and after purification
[0064]
[0065] Example 3
[0066] For crude indium with a content of In 96.13%, Sn 0.53%, Cd 0.14%, Cu 0.10%, and Pb 0.13%, electrolytic refining is used to prepare 99.995% refined indium. After a period of electrolysis, the ion content in the indium electrolyte is as follows: the mass-volume concentrations of In, Cl, Cd, Sn, Pb, Bi, Tl, and Zn are 42g / L, 54g / L, 0.58g / L, 0.121g / L, 0.031g / L, 0.007g / L, 0.008g / L, and 1.38g / L, respectively. The pH is 2.1. At this time, the impurity content in the indium electrolyte exceeds the standard and needs to be purified and removed. Figure 1 The process includes the following steps:
[0067] The first step is to prepare sponge indium: take the above-mentioned indium electrolyte with excessive impurity content and add zinc ingot, indium replacement temperature T = 80 ° C, replacement time t = 6h, end point pH = 4.0, and obtain fresh sponge indium.
[0068] The second step is sponge indium activation: the fresh sponge indium is added to deionized water and activated with ultrasound at a power of 100W. The sponge indium activation pH is 3.0, the activation time is t=80min, and the activation temperature is T=75°C to obtain an activated sponge indium with a porous structure having a lower impurity content and a high specific surface area.
[0069] The third step is purification and impurity removal: add sulfuric acid to the indium electrolyte with excessive impurity content after preparing the fresh sponge indium as mentioned above and control the acidity to 45g / L, turn on the ultrasonic wave and control the power to 70W, then add 60g of activated sponge indium per liter of indium electrolyte for reduction and adsorption purification, the purification and impurity removal temperature T = 70°C, the purification and impurity removal time t = 240min, and filter to obtain the purified indium electrolyte (qualified indium electrolyte) as shown in Table 3 below.
[0070] According to the crude indium electrolysis process conditions, crude indium purification electrolysis is carried out in the purified indium electrolyte, and the precipitated indium obtained meets the chemical composition table of In99995 refined indium "YS / T 257-2009 "Indium"".
[0071] Table 3 Indium and impurity content of indium electrolyte sponge before and after purification
[0072]
[0073] Comparative Example 1
[0074] For crude indium with a content of In 96.13%, Sn 0.53%, Cd 0.14%, Cu 0.10%, and Pb 0.13%, electrolytic refining is used to prepare 99.995% refined indium. After a period of electrolysis, the ion content in the indium electrolyte is as follows: the mass-volume concentrations of In, Cl, Cd, Sn, Pb, Bi, Tl, and Zn are 42g / L, 54g / L, 0.58g / L, 0.121g / L, 0.031g / L, 0.007g / L, 0.008g / L, and 1.38g / L, respectively. The pH is 2.1. At this time, the impurity content in the indium electrolyte exceeds the standard and needs to be purified and removed. Figure 1 The process includes the following steps:
[0075] The first step is to prepare sponge indium: take the above-mentioned indium electrolyte with excessive impurity content and add zinc ingot, indium replacement temperature T = 80 ° C, replacement time t = 6h, end point pH = 4.0, and obtain fresh sponge indium.
[0076] The second step is purification and impurity removal: sulfuric acid is added to the indium electrolyte with excessive impurity content after preparing the fresh sponge indium as described above, and the acidity is controlled to 45 g / L. The ultrasonic wave is turned on and the power is controlled to 70 W. Then, 60 g of activated sponge indium is added to each liter of indium electrolyte for reduction and adsorption purification. The purification and impurity removal T = 70 ° C, the purification and impurity removal time t = 240 min, and the purified indium electrolyte is obtained by filtration as shown in Table 4 below.
[0077] Comparative Example 1 did not undergo the "sponge indium activation" step, and crude indium purification electrolysis was carried out in the purified indium electrolyte according to the crude indium electrolysis process conditions. The precipitated indium obtained did not meet the chemical composition table of In9999 refined indium "YS / T 257-2009 "Indium"".
[0078] Table 4 Indium and impurity content of indium electrolyte sponge before and after purification
[0079]
[0080] Comparative Example 2
[0081] For crude indium with a content of In 96.13%, Sn 0.53%, Cd 0.14%, Cu 0.10%, and Pb 0.13%, electrolytic refining is used to prepare 99.995% refined indium. After a period of electrolysis, the ion content in the indium electrolyte is as follows: the mass-volume concentrations of In, Cl, Cd, Sn, Pb, Bi, Tl, and Zn are 42g / L, 54g / L, 0.58g / L, 0.121g / L, 0.031g / L, 0.007g / L, 0.008g / L, and 1.38g / L, respectively. The pH is 2.1. At this time, the impurity content in the indium electrolyte exceeds the standard and needs to be purified and removed. Figure 1The process includes the following steps:
[0082] The first step is to prepare sponge indium: take the above-mentioned indium electrolyte with excessive impurity content and add zinc ingot, indium replacement temperature T = 80°C, replacement time t = 6h, and end point pH = 4.0.
[0083] The second step is sponge indium activation: the fresh sponge indium is added to deionized water and activated with ultrasound at a power of 100W. The sponge indium activation pH is 3.0, the activation time is t=80min, and the activation temperature is T=75°C to obtain an activated sponge indium with a porous structure having a lower impurity content and a high specific surface area.
[0084] The third step is purification and impurity removal: the indium electrolyte with excessive impurity content after the preparation of fresh sponge indium is turned on with ultrasonic power controlled to 70W, and then 60g of activated sponge indium is added to each liter of indium electrolyte for reduction and adsorption purification. The purification and impurity removal temperature T = 70°C, the purification and impurity removal time t = 240min, and the purified indium electrolyte is obtained by filtration as shown in Table 5 below.
[0085] In Comparative Example 2, acid adjustment was not performed during purification and impurity removal. Crude indium purification electrolysis was carried out in the purified indium electrolyte according to the crude indium electrolysis process conditions. The precipitated indium obtained did not meet the chemical composition table of In9999 refined indium "YS / T 257-2009 "Indium"".
[0086] Table 5 Indium and impurity content of indium electrolyte sponge before and after purification
[0087]
[0088] 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 purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material, characterized in that: The purification and impurity removal method is used to purify and remove impurities from indium electrolyte with excessive impurity content during the process of preparing refined indium by electrolytic refining of crude indium, and comprises the following steps: Preparation of sponge indium: adding a reducing agent, zinc ingot, to the indium electrolyte with excessive impurity content to replace indium, thereby obtaining fresh sponge indium; Activating the indium sponge: activating the fresh indium sponge with ultrasound to obtain activated indium sponge; Purification and impurity removal: adding sulfuric acid to the indium electrolyte with excessive impurity content to control the sulfuric acid content to 20 g / L-70 g / L, then adding the activated sponge indium to purify and remove impurities, and filtering to obtain a qualified indium electrolyte; Among them, the qualified indium electrolyte composition indicators include: In ions: 40g / L-100g / L, Cl ions: 25g / L-72g / L, Cd ions ≤1.0g / L, Sn ions ≤0.01g / L, Pb ions ≤0.01g / L, Zn ions <3g / L, Bi ions ≤0.005g / L, Tl ions ≤0.001g / L.
2. The method for purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material according to claim 1, characterized in that: In the preparation of the sponge indium, the indium replacement temperature is 65° C.-96° C., the indium replacement time is 5 h-8 h, and the indium replacement endpoint pH is 3.2-4.
5.
3. The method for purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material according to claim 1, characterized in that: In the activation of the sponge indium, the activation temperature is 65° C.-85° C., the activation time is 30 min-120 min, and the activation pH is 2.5-3.
8.
4. The method for purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material according to claim 3, characterized in that: The activation is performed by ultrasonic wave, and the power of the ultrasonic wave is 75W-120W.
5. The method for purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material according to claim 1, characterized in that: During the purification and impurity removal, the amount of the activated sponge indium added is 40g-80g per liter of the indium electrolyte with excessive impurity content, the purification and impurity removal temperature is 55°C-90°C, and the purification and impurity removal time is 120min-360min.
6. The method for purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material according to claim 5, characterized in that: The purification and impurity removal is carried out under ultrasonic conditions, and the power of the ultrasonic waves is 60W-80W.
7. The method for purifying and removing impurities from indium electrolyte using fresh sponge indium as raw material according to claim 1, characterized in that: The crude indium is electrolytically refined, and the composition of the anode crude indium satisfies In≥95.20%, Sn≤0.65%, Cd≤0.18%, Cu≤0.12% and Pb≤0.16%.