Method for directly electrolyzing and recycling ITO (indium tin oxide) waste

Abstract

The invention provides a direct electrolysis recycling method for ITO waste, belongs to the technical field of smelting separation and purification of scattered metal indium, and aims to solve the problems of low electrolysis recycling rate and high cost of the ITO waste. The invention provides an ITO waste direct electrolysis recovery method. The ITO waste direct electrolysis recovery method comprises the following steps that ITO waste is made into an ITO mixed oxide plate; preparing an indium electrolyte; the ITO mixed oxide plate is used as an anode plate, the ITO mixed oxide plate and the cathode plate are placed in the indium electrolyte together for electrolysis, and animal glue, an activating agent and a precipitating agent are added into the indium electrolyte. According to the method, electrolysis separation of indium and simultaneous purification of the indium electrolyte can be achieved under the condition of an electrolytic bath without special requirements, the quality of separated indium is guaranteed, continuous production is guaranteed, the investment cost of direct electrolysis recovery of ITO waste is reduced, and meanwhile the production cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of smelting, separation and purification of rare dispersed metal indium, and particularly relates to a method for directly electrolyzing and recovering ITO waste materials. Background Art

[0002] Indium is an important strategic metal and has extensive applications in fields such as electronic communication, national defense industry, energy medicine, etc. As a rare dispersed metal, the content of indium in the earth's crust is 1×10 -5 %, and it is dispersed, mostly associated with important non-ferrous metal minerals such as zinc, lead, and copper. Therefore, the extraction raw materials of indium are complex, there are many extraction methods and the extraction route is long. With the exhaustion of primary indium resources, it is particularly important to recycle indium from secondary indium resources.

[0003] Currently, the main application of indium is still in the field of flat panel display, including traditional ITO targets and emerging indium gallium zinc oxides and indium for bonding, accounting for about 80% of the global indium application field; in industrial applications, the utilization rate of ITO target sputtering coating is generally 30 - 40%, and the remaining part becomes waste targets. Coupled with the scraps, grinding powders, cutting powders and waste products generated during the forming process of the targets, they are collectively referred to as ITO waste materials; usually, ITO targets are composed of indium oxide and tin oxide, among which the mass percentage content of tin oxide (SnO2) is about 9.7%, and the rest is indium oxide (In2O3). Therefore, the indium content in ITO waste targets is as high as 78%. Therefore, recycling metal In from waste targets has become the main source of recycled In.

[0004] The traditional comprehensive recycling technology of ITO waste targets lies in the effective separation of In and Sn. It mainly utilizes the differences in the physical and chemical properties of In and Sn, and methods such as electrolysis, hydrolysis precipitation, alkali method separation, and replacement can be used. However, these methods have deficiencies such as incomplete separation of In and Sn and low efficiency. At the same time, the recovery rate of In in ITO targets is relatively low, and metal Sn is recovered and processed as tin raw materials in the form of intermediate material tin oxide. At the same time, there are also problems such as low recovery rates of indium and tin, high energy consumption, high equipment maintenance costs, and it is difficult to obtain refined indium and refined tin, and the direct recovery rate is low. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a method for directly electrolyzing and recovering ITO waste materials, which can recover valuable metals from used indium - tin oxide (ITO) sputtering targets, ITO scraps generated during manufacturing, or ITO powders generated during processing, etc.

[0006] To solve the above problems, the present invention provides a method for directly electrolyzing and recovering ITO waste materials, including the following steps:

[0007] Making the ITO waste materials into ITO mixed oxide plates;

[0008] Prepare indium electrolyte;

[0009] Use the ITO mixed oxide plate as the anode plate, place it together with the cathode plate in the indium electrolyte, conduct electrolysis, and add gelatin, activator and precipitant to the indium electrolyte.

[0010] Optionally, make the ITO waste into an ITO mixed oxide plate, including:

[0011] Cut the ITO waste to form an ITO waste plate and remaining materials;

[0012] Grind the remaining materials to form ITO powder;

[0013] Mix the ITO powder, binder and water according to the mass percentage of ITO powder: binder: water = 1: 0.005 - 0.012: 0.01 - 0.03, and after mixing evenly, perform cold isostatic pressing to form an ITO powder plate;

[0014] Both the ITO waste plate and the ITO powder plate serve as the ITO mixed oxide plate.

[0015] Optionally, the indium electrolyte is an In2(SO4)3-H2SO4 system electrolyte; preparing the indium electrolyte includes:

[0016] Melt refined indium at high temperature to form liquid refined indium;

[0017] Water-break the liquid refined indium to form indium flowers;

[0018] Cool the indium flowers to a preset temperature;

[0019] Dissolve the indium flowers with sulfuric acid with a volume percentage concentration of 200 g / L - 300 g / L, and slowly add sodium chloride during the dissolution process according to the chloride ion control requirements.

[0020] Optionally, preparing the indium electrolyte further includes:

[0021] After the indium flowers are dissolved, adjust the pH of the solution with sodium hydroxide, and add sodium chloride and water for volume fixing according to the component requirements.

[0022] Optionally, the H2SO4 system of the indium electrolyte includes an activator Cl - , Cl - The volume percentage content is 3 - 25 g / L.

[0023] Optionally, the components of the indium electrolyte are (unit: g / L, volume percentage content): In 73 - 98, Cl - 64 - 72, Cd ≤ 1.0, Sn ≤ 0.005, Pb ≤ 0.008, Zn ≤ 1.54.

[0024] Optionally, an ITO mixed oxide plate is used as the anode plate, which is placed in indium electrolyte together with the cathode plate. The control conditions for the electrolysis process are as follows: the same-pole distance is 70 - 82 mm, the current density A = 82 - 98 A / m 2 , the pH of the electrolyte is 1.5 - 2.0, the precipitation period is 96 - 192 h, and the electrolysis temperature is 32 - 38 °C.

[0025] Optionally, hydrogen peroxide is used as the activator; barium chloride is used as the precipitant.

[0026] Optionally, the precipitant is a solution prepared by mixing barium chloride and deionized water with a volume percentage concentration of 45 - 250 g / L.

[0027] Optionally, the cathode plate is one of a titanium plate, a stainless steel plate, and refined indium. The length and width dimensions of the anode plate are 5 - 20 mm smaller than those of the cathode plate respectively.

[0028] Beneficial effects

[0029] The ITO waste direct electrolysis recovery method provided by the present invention directly uses ITO waste as the anode and an electrolyte with conventional components as the indium electrolyte, and can directly electrolytically precipitate 99.995% of refined indium; at the same time, tin is recovered from the anode mud in the form of tin dioxide precipitation. The present invention can realize the electrolytic precipitation of indium and the simultaneous purification of indium electrolyte under the conditions of an electrolytic cell without special requirements, ensuring both the quality of the precipitated indium and continuous production, and reducing both the investment cost and production cost of the direct electrolysis recovery of ITO waste. Description of the drawings

[0030] Figure 1 is a flow chart of an ITO waste direct electrolysis recovery method provided by an embodiment of the present invention;

[0031] Figure 2 is a flow chart of another ITO waste direct electrolysis recovery method provided by an embodiment of the present invention;

[0032] Figure 3 is a flow chart of yet another ITO waste direct electrolysis recovery method provided by an embodiment of the present invention;

[0033] Figure 4 is a process flow chart of an ITO waste direct electrolysis recovery method provided by an embodiment of the present invention. Detailed implementation manners

[0034] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The present invention includes other embodiments and their deformations within the scope of its technical idea.

[0035] Figure 1 It is a flowchart of a method for directly electrolytically recovering ITO waste provided by the present invention in an embodiment. Figure 2 It is a flowchart of another method for directly electrolytically recovering ITO waste provided by the present invention in an embodiment. Figure 3 It is a flowchart of yet another method for directly electrolytically recovering ITO waste provided by the present invention in an embodiment. Figure 4 It is a process flowchart of a method for directly electrolytically recovering ITO waste provided by the present invention in an embodiment.

[0036] As Figure 1 shown, a method for directly electrolytically recovering ITO waste provided by an embodiment of the present invention includes the following steps:

[0037] S1. Make the ITO waste into an ITO mixed oxide plate.

[0038] Specifically, the ITO mixed oxide plate is rectangular, and its length and width dimensions are respectively 5-20 mm smaller than the length and width dimensions of the cathode plate. The length and width of the cathode plate can be determined according to the height and width of the indium electrolytic cell used.

[0039] S2. Configure indium electrolyte.

[0040] S3. Use the ITO mixed oxide plate as the anode plate and place it together with the cathode plate in the indium electrolyte for electrolysis, and add gelatin, activator and precipitant to the indium electrolyte.

[0041] Specifically, the addition amount of gelatin is: add 0.5-1 g / m 3 gelatin per cubic meter of indium electrolyte, and it needs to be added slowly. The addition amount of the activator is: add 800-2000 mL of activator per cubic meter of indium electrolyte. At the same time, add a precipitant, and the addition amount of the precipitant is: add 5-80 g of precipitant per cubic meter of indium electrolyte, and it is slowly dripped in.

[0042] The present invention can achieve full coverage of ITO waste through one-step electrolysis. By adding an activator and a precipitant, 99.995% of refined indium can be produced through one-step electrolysis, and high-quality tin dioxide products can be prepared. The present invention has the advantages of reasonable process, low equipment investment cost, environmental friendliness, non-toxicity, etc. The direct recovery rate of indium during the indium electrolysis process reaches 97.85%, and the total recovery rate exceeds 98.68%. The present invention produces no "three wastes" and has a very broad application prospect.

[0043] Among them, as Figure 2 shown, S1. Making the ITO waste into an ITO mixed oxide plate, specifically including the following steps:

[0044] S11. Cutting the ITO waste to form an ITO waste plate and remaining materials;

[0045] Specifically, the ITO waste is cut with the length and width dimensions being respectively 5 - 20 mm less than the length and width dimensions of the cathode plate during the production process to obtain a rectangular ITO waste plate.

[0046] S12. Grinding the remaining materials to form ITO powder;

[0047] Specifically, the remaining materials are some smaller scraps or powders, and these remaining materials are ball-milled into ITO powder. Among them, in the ITO powder, the mass percentage of materials with a particle size exceeding 200 meshes accounts for 70 - 85%.

[0048] S13. Mixing according to the mass percentage of ITO powder: binder: water = 1: 0.005 - 0.012: 0.01 - 0.03, and after mixing evenly, performing cold isostatic pressing to form an ITO powder plate;

[0049] Specifically, deionized water is used for the water in the formulation. The length and width dimensions of the ITO powder plate are respectively 5 - 20 mm less than the length and width dimensions of the cathode plate during the production process.

[0050] S14. Both the ITO waste plate and the ITO powder plate serve as the ITO mixed oxide plate.

[0051] By cutting the larger ITO waste to obtain an ITO waste plate, then crushing and mixing the smaller scraps and powders in the remaining materials, and then performing cold isostatic pressing to obtain an ITO powder plate, the full recovery of ITO waste is ensured. At the same time, the present invention directly cuts the larger ITO waste to prepare the ITO mixed oxide plate, reducing the production cost of the anode plate, also ensuring that the anode plate resistance is below 0.1 Ω, reducing the cell voltage of indium electrolysis, improving the electro- efficiency, and being beneficial to reducing the power consumption of indium electrolysis.

[0052] By controlling the crushing particle size of ITO waste, selecting the proportion and types of ingredients, and adding cold isostatic pressing, the resistance of the formed anode plate is ensured to be about 0.09 Ω, the cell voltage is reduced, the current efficiency is improved, the electrolysis current efficiency can reach 99%, and the power consumption is controlled within 4 kWh / kg of indium precipitation.

[0053] Among them, the indium electrolyte is an In2(SO4)3-H2SO4 system electrolyte; as Figure 3 shown, S2. Configure the indium electrolyte, specifically including the following steps:

[0054] S21. Melt refined indium at high temperature to form liquid refined indium;

[0055] Specifically, refined indium with a purity of 99.995% or more is used for configuring the indium electrolyte.

[0056] S22. Water-quench the liquid refined indium to form indium flowers;

[0057] Specifically, deionized water is used for water quenching.

[0058] S23. Cool the indium flowers to a preset temperature;

[0059] Specifically, the preset temperature T = 85 - 96 °C.

[0060] S24. Dissolve the indium flowers with sulfuric acid with a volume percentage concentration of 200 g / L - 300 g / L, and slowly add sodium chloride during the dissolution process according to the requirements of chloride ion control.

[0061] Specifically, the purity of the sulfuric acid used is analytical pure.

[0062] Using refined indium to configure the indium electrolyte ensures that the impurity content in the indium electrolyte is controlled within the range of indium electrolyte components, which can further improve the quality of precipitated indium, and the content of precipitated refined indium can exceed 99.998%; melting refined indium at high temperature and directly performing water quenching ensure that there is no passivation phenomenon on the surface of indium flowers and the refined indium is in the shape of fine snowflakes. At the same time, under the activation conditions of high temperature, high acid and the presence of Cl - ions, the dissolution rate of indium can be reduced from 1 - 2 days to 2 - 3 hours, saving production costs.

[0063] Among them, as Figure 3 shown, S2. Configure the indium electrolyte, and also includes the following steps:

[0064] S25. After the indium flowers are dissolved, use sodium hydroxide to adjust the pH of the solution, and add sodium chloride and water for volume fixation according to the component requirements.

[0065] Specifically, the purity of the sodium chloride used is analytical pure, and the water used is deionized water.

[0066] Among them, the H2SO4 system of indium electrolyte includes an activator Cl - , Cl - The volume percentage content is 3 - 25 g / L.

[0067] Among them, the components of the indium electrolyte are (unit: g / L, volume percentage content): In 73 - 98, Cl - 64 - 72, Cd ≤ 1.0, Sn ≤ 0.005, Pb ≤ 0.008, Zn ≤ 1.54.

[0068] Among them, the ITO mixed oxide plate is used as the anode plate and placed in the indium electrolyte together with the cathode plate. The control conditions for the electrolysis process are: the same - pole distance is 70 - 82 mm, the current density A = 82 - 98 A / m 2 , the pH of the electrolyte: 1.5 - 2.0, the precipitation period is 96 - 192 h, and the electrolysis temperature is 32 - 38 °C.

[0069] In the indium electrolyte, tin generally exists in the forms of Sn 2+ and Sn 4+ . Among them, Sn 4+ is more likely to undergo hydrolysis reaction to produce charged colloidal tin glue, and the complete precipitation pH is above 1.25. While the colloidal tin glue produced by the hydrolysis of Sn 2+ completely precipitates at a pH above 2.6, and the hydrolysis pH of In 3+ is higher than that of Sn 2+ , and the pH exceeds 3.0; the relevant chemical formulas are as follows. In this experiment, the pH is controlled at 1.5 - 2.0. To ensure the purity of indium precipitated at the cathode, hydrogen peroxide needs to be continuously added to the electrolyte during the electrolysis process to oxidize Sn 2+ to Sn 4+ , so as to completely precipitate tin.

[0070] Hydrolysis reaction of Sn 4+ :

[0071] Hydrolysis reaction of Sn 2+ :

[0072] Hydrolysis reaction of In 3+ :

[0073] In order to ensure that the anode mud contains as little entrained and precipitated In(OH)3 as possible, improve the direct recovery rate of indium, and ensure the quality of tin dioxide in the anode mud, the measures taken in the present invention are to control the pH and add hydrogen peroxide, and at the same time control the same - pole distance and current density to ensure.

[0074] In addition, the control of the same electrode distance, current density, electrolysis temperature, and precipitation period is a comprehensive selection based on a large number of test results and the improvement of current efficiency, reduction of power consumption, and guarantee of the quality of precipitated indium. If the same electrode distance is too small, the quality of precipitated indium will decline; if it is too large, the current efficiency will decrease and the power consumption will increase. If the current density is too small, the quality of precipitated indium will increase, but the production efficiency will decline and the production cost will increase. If the electrolysis temperature is too low, the current efficiency will decline and the power consumption will increase; if the electrolysis temperature is too high, the energy consumption will increase and the production cost will increase.

[0075] Among them, hydrogen peroxide is used as the activator; barium chloride is used as the precipitant. The addition amount of barium chloride is: 5 - 80 g of barium chloride is added per cubic meter of indium electrolyte, and it is slowly dropped in.

[0076] Generally, tin dioxide is α-SnO2, and α-SnO2 is soluble in strong acids. After being treated at high temperature or activated by a strong oxidant, α-SnO2 is converted into β-SnO2 that is insoluble in strong acids. Adding hydrogen peroxide as the activator in the present invention has two functions: that is, it has the function of oxidizing Sn 2+ to Sn 4+ and also has the function of converting α-SnO2 into β-SnO2, thereby ensuring that the content of tin ions in the indium electrolyte is controlled within Sn≤0.005 g / L.

[0077] Sn 4+ is more likely to undergo a hydrolysis reaction to produce charged colloidal tin glue, which is difficult to form particles and precipitate in the indium electrolyte, and may thus precipitate from the precipitated indium, resulting in a decline in the quality of the precipitated indium and making it difficult to guarantee the quality of refined indium. The addition of barium chloride is to generate barium sulfate precipitate with an opposite charge to that of tin dioxide, and to completely form particles of tin dioxide colloid by borrowing the principle of attracting opposite charges; the structure of barium sulfate is similar to that of tin dioxide and has an opposite charge, so that the positive and negative charges interact with each other, ensuring that tin dioxide grows into large particles and precipitates in a timely manner.

[0078] Furthermore, the precipitant is a solution prepared by barium chloride and deionized water with a volume percentage concentration of 45 - 250 g / L, and it is slowly added. The reasons for dissolving barium chloride into a solution before adding, controlling the addition amount, and slowly adding are to improve the quality of tin dioxide, reduce the production cost, and make tin dioxide precipitate completely. If the combined method is not controlled, barium chloride will react completely in a short time after adding, resulting in the inability of newly formed tin dioxide colloid to precipitate later and a decline in the quality of the precipitated indium.

[0079] Among them, the cathode plate is one of a titanium plate, a stainless steel plate, and refined indium.

[0080] The ITO waste direct electrolysis recovery method provided by the embodiment of the present invention has a process flow as Figure 4 shown. The following specifically describes the ITO waste direct electrolysis recovery method provided by the present invention through examples.

[0081] Example 1

[0082] For a block-shaped, sputtered ITO waste material that is larger than the cathode plate, it is processed according to the Figure 4 process flow, including the following steps:

[0083] First step: Preparation of the anode plate. The ITO waste material is cut so that its length and width are each less than 5 mm of the cathode plate, obtaining a rectangular ITO waste material plate;

[0084] Second step: Preparation of indium electrolyte. The indium electrolyte adopts the In2(SO4)3-H2SO4 system. Using 99.995% pure indium as the raw material, indium flowers are prepared, and then dissolved in a 200 g / L sulfuric acid solution at T = 96 °C. During the dissolution process, sodium chloride is added according to a chlorine content of 3 g / L. After dissolution is completed, the pH is adjusted to 2, and at the same time, sodium chloride is added to make the electrolyte composition (unit: g / L): In 73, Cl- 72, Cd 0.001, Sn 0.0008, Pb 0.0008, Zn 0.001;

[0085] Third step: Electrolysis. Using the obtained rectangular ITO waste material plate as the anode plate and a titanium plate as the cathode plate, the same electrode distance is 82 mm, the current density A = 98 A / m 2 , the pH of the electrolyte is 2.0, the precipitation period is 96 h, the electrolysis temperature is 32 °C, and the amount of gelatin added is slowly added according to 0.5 g / m 3 the amount of indium electrolyte. The amount of activator added is added according to 2000 mL / m 3 the amount of indium electrolyte. Barium chloride is prepared into a 45 g / L solution and slowly dripped in according to 5 g / m 3 the amount of indium electrolyte.

[0086] After cutting the sputtered residual ITO waste material, it is directly electrolyzed in one step as the anode plate. The obtained product, refined indium, has a grade of 99.998%, and the quality of the anode mud, tin dioxide, meets the product requirements; the electrolysis current efficiency is 99.25%, the power consumption is 3.65 kWh / kg of precipitated indium, the direct recovery rate of indium during the indium electrolysis process is 97.97%, and the total recovery rate is 98.92%.

[0087] Example 2

[0088] For ITO corner waste materials, they are processed according to the Figure 4 process flow, including the following steps:

[0089] Step 1: Preparation of anode plate: crush and ball-mill the ITO scraps in the remaining materials, so that 70% of the materials pass through a 200-mesh screen, mix and mix the materials according to the mass percentage of ITO: binder: water = 1:0.012:0.01, and then perform cold isostatic pressing to form an ITO powder plate with a length and width that is 20 mm less than the length and width of the cathode plate;

[0090] Step 2: Indium electrolyte preparation: Indium electrolyte adopts In2(SO4)3-H2SO4 system, and indium flower is prepared with 99.995% refined indium as raw material, and then dissolved in 300g / L sulfuric acid solution at T=85℃. During the dissolution process, sodium chloride is added according to 25g / L chlorine content. After the dissolution is completed, pH=1.5 is adjusted, and sodium chloride is added at the same time, so that the electrolyte composition (unit g / L): In 98, Cl-64, Cd 1.0, Sn 0.005, Pb0.008, Zn 1.54;

[0091] Step 3: Electrolysis: The rectangular ITO powder plate obtained by cold isostatic pressing is used as the anode plate, the titanium plate is used as the cathode plate, the inter-electrode distance is 70 mm, and the current density is A = 82 A / m 2 , electrolyte pH: 1.5, precipitation cycle is 192h, electrolysis temperature is 38℃, and the amount of animal glue added is 1g / m 3 The amount of indium electrolyte was slowly added, and the amount of activator added was 800mL / m 3 Add the amount of indium electrolyte, barium chloride to make a 250g / L solution, and 80g / m 3 The amount of indium electrolyte is slowly added dropwise.

[0092] The ITO waste after crushing and ball milling is made into ITO powder plates through batching and cold isostatic pressing. The ITO powder plates are directly electrolyzed in one step to obtain a product with a refined indium grade of 99.996%, and the quality of anode mud tin dioxide meets the product requirements; the electrolysis current efficiency is 99.31%, the power consumption is 3.73 kWh / kg of precipitated indium, the direct recovery rate of indium in the indium electrolysis process is 97.92%, and the total recovery rate is 99.15%.

[0093] Example 3

[0094] For ITO waste powder Figure 4 The process includes the following steps:

[0095] Step 1: Anode plate preparation: ITO waste powder, 85% of which can pass through a 200-mesh screen, is mixed and evenly prepared according to the mass percentage of ITO: binder: water = 1:0.005:0.03, and then cold isostatically pressed to form an ITO powder plate with a length and width that is 12 mm smaller than the length and width of the cathode plate;

[0096] Step 2: Indium electrolysis is also configured: Indium electrolyte adopts In2(SO4)3-H2SO4 system, and 99.995% refined indium is used as raw material to prepare indium flower, and then 260g / L sulfuric acid solution is used to dissolve it at T=90℃. During the dissolution process, sodium chloride is added according to the chlorine content of 14g / L. After the dissolution is completed, the pH is adjusted to 1.8, and sodium chloride is added at the same time to make the electrolyte composition (unit g / L): In 88, Cl-68, Cd 0.05, Sn 0.001, Pb 0.002, Zn 0.045;

[0097] Step 3: Electrolysis: ITO powder plate is used as anode plate, titanium plate is used as cathode plate, the same pole distance is 87mm, and the current density is A=91A / m 2 , electrolyte pH: 1.8, precipitation cycle: 120h, electrolysis temperature: 35℃, animal glue addition amount: 0.8g / m 3 The amount of indium electrolyte was slowly added, and the amount of activator added was 1300mL / m 3 Add the amount of indium electrolyte, barium chloride to make a 150g / L solution, and 45g / m 3 The amount of indium electrolyte is slowly added dropwise.

[0098] Using ITO powder plate as anode plate, direct electrolysis in one step can obtain a product with a refined indium grade of 99.997%, and the quality of anode mud tin dioxide meets product requirements; the electrolysis current efficiency is 99.35%, the power consumption is 3.81 kWh / kg of precipitated indium, the direct recovery rate of indium in the indium electrolysis process is 98.33%, and the total recovery rate is 99.11%.

[0099] Example 4

[0100] For ITO scraps, Figure 4 The process includes the following steps:

[0101] Step 1: Anode plate preparation: ITO scraps are crushed and ball-milled to make 80% of the materials pass through a 200-mesh screen, and the materials are mixed according to the mass percentage of ITO: binder: water = 1:0.010:0.02 and then cold isostatically pressed to form an ITO powder plate with a length and width smaller than the length and width of the negative titanium plate by 14 mm;

[0102] Step 2: Preparation of indium electrolyte: The indium electrolyte adopts the In2(SO4)3-H2SO4 system. High-purity indium of the 99.995% model is used as the raw material to prepare indium flowers, which are then dissolved in a 220 g / L sulfuric acid solution at T = 94°C. During the dissolution process, sodium chloride is added according to a chlorine content of 11 g / L. After dissolution, the pH is adjusted to 1.9, and sodium chloride is added simultaneously to make the electrolyte composition (unit: g / L): In 90, Cl- 65, Cd 0.07, Sn 0.0009, Pb 0.0002, Zn 0.022;

[0103] Step 3: Electrolysis: Using the ITO powder plate as the anode plate and the titanium plate as the cathode plate, the same pole distance is 73 mm, and the current density A = 94 A / m 2 , the pH of the electrolyte is 1.9, the precipitation period is 178 h, the electrolysis temperature is 34°C, and the amount of gelatin added is slowly added according to 0.6 g / m 3 of the indium electrolyte. The amount of the activator added is added according to 1500 mL / m 3 of the indium electrolyte. Barium chloride is prepared into a 123 g / L solution and slowly dripped in according to 50 g / m 3 of the indium electrolyte.

[0104] Using the ITO powder plate as the anode plate, direct electrolysis is carried out in one step to obtain refined indium with a grade of 99.998%. The quality of the anode mud tin dioxide meets the product requirements; the electrolysis current efficiency is 99.52%, the power consumption is 3.96 kWh / kg of precipitated indium, the direct recovery rate of indium during the indium electrolysis process is 97.91%, and the total recovery rate is 99.17%.

[0105] Since the types and contents of the impurities doped in the ITO waste will cause different compositions of the ITO waste, therefore, certain auxiliary materials can be added or reduced according to the composition of the ITO waste. However, as long as the basic process flow remains unchanged, it still belongs to the protection scope of the present invention.

[0106] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for directly electrolytically recovering ITO waste, characterized in that, It includes the following steps: Making ITO waste into an ITO mixed oxide plate; Preparing indium electrolyte; Placing the ITO mixed oxide plate as the anode plate and the cathode plate together in the indium electrolyte for electrolysis, and adding gelatin, activator and precipitant to the indium electrolyte.

2. The ITO waste direct electrolysis recovery method according to claim 1, characterized in that, The step of making ITO waste into an ITO mixed oxide plate includes: Cutting the ITO waste to form an ITO waste plate and remaining materials; Grinding the remaining materials to form ITO powder; Mixing according to the mass percentage of ITO powder: binder: water = 1: 0.005 - 0.012: 0.01 - 0.03, and performing cold isostatic pressing after mixing evenly to form an ITO powder plate; Using the ITO waste plate and the ITO powder plate as the ITO mixed oxide plate.

3. The ITO waste direct electrolysis recovery method according to claim 1, characterized in that, The indium electrolyte is an In2(SO4)3-H2SO4 system electrolyte; The step of preparing indium electrolyte includes: Melting refined indium at high temperature to form liquid refined indium; Water granulating the liquid refined indium to form indium flowers; Cooling the indium flowers to a preset temperature; Dissolving the indium flowers with sulfuric acid having a volume percentage concentration of 200 g / L - 300 g / L, and slowly adding sodium chloride during the dissolution process according to the chloride ion control requirements.

4. The ITO waste direct electrolysis recovery method according to claim 3, characterized in that, The step of preparing indium electrolyte further includes: After the indium flowers are dissolved, adjusting the pH of the solution with sodium hydroxide, and making up the volume with sodium chloride and water according to the component requirements.

5. The ITO waste direct electrolysis recovery method according to claim 3, characterized in that, The H2SO4 system of the indium electrolyte includes an activator Cl - , Cl - The volume percentage content is 3-25g / L.

6. The ITO waste direct electrolysis recovery method according to claim 1, characterized in that The composition of the indium electrolyte is (unit: g / L, volume percentage content): In 73-98, Cl - 64-72, Cd ≤ 1.0, Sn ≤ 0.005, Pb ≤ 0.008, Zn ≤ 1.

54.

7. The method for directly electrolytically recovering ITO waste according to claim 1, characterized in that, Take the ITO mixed oxide plate as the anode plate and place it together with the cathode plate in the indium electrolyte. The control conditions for the electrolysis process are as follows: the same-pole distance is 70 - 82 mm, the current density A = 82 - 98 A / m 2 , the pH of the electrolyte: 1.5 - 2.0, the precipitation period is 96 - 192 h, and the electrolysis temperature is 32 - 38 °C.

8. The ITO waste direct electrolysis recovery method according to claim 1, characterized in that The activator is hydrogen peroxide; the precipitant is barium chloride.

9. The ITO waste direct electrolysis recovery method according to claim 8, wherein, The precipitant is a solution prepared by mixing barium chloride and deionized water with a volume percentage concentration of 45 - 250 g / L.

10. The method for directly electrolytically recovering ITO waste according to claim 1, wherein The cathode plate is one of a titanium plate, a stainless steel plate and refined indium; the length and width dimensions of the anode plate are respectively 5 - 20 mm smaller than the length and width dimensions of the cathode plate.

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