Method for recovering indium from waste target material

Abstract

The application discloses a method for recovering indium from waste target material, which comprises the following steps: (1) leaching: adding hydrochloric acid solution into ITO target material waste, heating and stirring under ultrasonic wave, leaching for a certain time, filtering, and obtaining acid dissolution residue and leaching solution; (2) electrolytic separation of tin: placing the leaching solution in an electrolytic cell to perform micro-current electrolysis, filtering, and taking the filtrate; (3) electrolytic separation of indium: performing micro-current electrolysis on the filtrate again, and taking the sinking sponge indium deposited at the bottom of the cell; and (4) briquetting and drying: after the sinking sponge indium is briquetted, dried and smelted, finished products are obtained. The application effectively avoids the occurrence of the phenomenon of "indium wrapping zinc" and the like during traditional zinc powder replacement, the zinc content in the sponge indium is greatly reduced, the grade of the obtained indium is 99.998%, which meets the industry standard, strong-current electrolysis is not needed, and the energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of ITO target material recycling, and particularly relates to a method for recovering indium from waste target material. BACKGROUND

[0002] Indium Tin Oxide (ITO) target material is an oxide ceramic sintered body composed of In2O3 and SnO2 in a mass ratio of 9:1. ITO thin film prepared therefrom has good light transmittance and conductivity, and is an irreplaceable transparent electrode material for current flat panel displays. At present, ITO thin film is almost produced by the method of magnetron sputtering coating of ITO target material. However, the actual utilization rate of ITO target material in the coating process is only about 30%, and the remaining part becomes waste target, in addition to the edge scraps and cuttings generated in the forming process of the target material, which causes serious waste of indium resources.

[0003] ITO waste target contains a large amount of scattered indium, which is an important secondary resource of indium. At present, the indium used for manufacturing ITO target material accounts for 40-50% of the total output. According to statistics, the content of indium in ITO waste target produced in China each year is more than 300 tons, while the proven indium reserves in China are only about 8000 tons. Therefore, developing an efficient short-process ITO waste target recovery process technology is of great significance to the sustainable development of China's indium industry. SUMMARY

[0004] The purpose of the present application is to solve the above technical problems and provide a method for recovering indium from waste target material which can improve the grade of indium.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows:

[0006] A method for recovering indium from waste target material, comprising the following steps:

[0007] (1) Leaching: adding hydrochloric acid solution to ITO target waste, heating and stirring under ultrasonic wave, leaching for a certain time, filtering to obtain acid-soluble residue and leaching solution;

[0008] (2) Electrolytic separation of tin: placing the leaching solution in an electrolytic cell for micro-current electrolysis, filtering and taking the filtrate;

[0009] (3) Electrolytic separation of indium: performing micro-current electrolysis on the filtrate again, and taking the sinking sponge indium precipitated at the bottom of the cell;

[0010] (4) Pressing, drying: pressing, drying and casting the sinking sponge indium to obtain a finished product.

[0011] As a further technical solution, the liquid-solid ratio of the ITO target waste and the hydrochloric acid solution is 1g:(20-30)ml, and the concentration of the hydrochloric acid solution is 6-7mol / L.

[0012] As a further technical solution, the power of the ultrasonic wave is 300-800W.

[0013] As a further technical solution, the temperature of the heating and stirring is 80-90℃, and the leaching time is 3-4h.

[0014] As a further technical solution, in the two micro-current electrolysis, a large-size zinc plate is used as the anode, and a small-size titanium plate or stainless steel plate is used as the cathode.

[0015] As a further technical solution, the current density of the step (2) micro-current electrolysis is 20A / m 2 -40A / m 2 , the temperature is 70-90℃, and the electrolysis time is 3-5h.

[0016] As a further technical solution, the current density of the step (3) micro-current electrolysis is 20A / m 2 -40A / m 2 , the temperature is 70-90℃, and the electrolysis time is 6-10h.

[0017] Compared with the prior art, the beneficial effects of the present application are:

[0018] The present application uses micro-current "non-uniform electric field" technology to purify indium. Different sizes of anode plates and cathode plates are used to form a non-uniform electric field, and a small current is applied to form a "weak non-uniform electric field" in the leaching solution. Under the action of the weak non-uniform electric field, the anode zinc plate first reacts with tin in the solution: Sn 4+ +2Zn =2Zn 2+ +Sn↓, which can remove 99.5% of the tin ions in the leaching solution, and then the anode zinc plate reacts with indium in the solution: 2In 3+ +3Zn =3Zn 2+ +2In↓, which can finally purify the indium. On the other hand, in step (3), under the action of the micro-current, fine electric sols are generated on the surface of the anode zinc plate, and the indium ions in the solution rapidly exchange electrons with the anode zinc, and the indium ions are reduced to elemental indium on the surface of the zinc anode, while the zinc loses electrons and turns into zinc ions in the solution. The newly reduced indium cannot stick to the zinc plate due to the electric sol of the inner layer zinc and falls to the bottom of the tank to form sponge indium, and the newly exposed zinc on the zinc sheet continues to exchange electrons with the cadmium ions in the solution under the action of the micro-current. The existence of the weak "non-uniform electric field" makes Zn←→In 3+The electronic exchange speed is accelerated; this mode effectively avoids the occurrence of the phenomenon of "indium wrapping zinc" existing in traditional zinc powder replacement, the zinc content in the sponge indium is greatly reduced, and then the grade of the indium is 99.998%, which meets the industry standard, strong current electrolysis is not needed, and the energy consumption is reduced.

[0019] In the leaching stage, the application adopts ultrasonic waves, more indium can be leached, and the recovery rate of indium is improved. DETAILED DESCRIPTION

[0020] The application will be further described in detail in combination with examples, but the implementation manner of the application is not limited to the range indicated by the examples.

[0021] The ITO target material waste used in the embodiment has the following main chemical components: In2O388.76 %, SnO210.33 %. Example 1

[0022] A method for recovering indium from waste target material, comprising the following steps:

[0023] (1) Leaching: 50g of ITO target material waste is added into 1L of 6mol / L hydrochloric acid solution, the pH of the solution is controlled to be between 2 and 3. The solution is heated to 80-90℃ under ultrasonic waves, and leached for 3h, and then filtered to obtain tin oxide acid solution residue and leaching solution; in the acid system, SnO2 is stable, which can reduce the reaction dissolution, and this is very beneficial to the separation of indium and tin. The power of the ultrasonic wave is 300-800W, after the addition of ultrasonic wave assistance, the indium leaching rate is above 98.5 %, and the tin leaching rate is 30 %.

[0024] (2) Electrolytic separation of tin: the leaching solution is placed in an electrolytic tank for micro-current electrolysis, and then filtered to obtain a filtrate; according to the reaction activity of indium and tin, in this step, mainly tin ions are replaced out. The current density of the micro-current electrolysis is 20A / m 2 , the temperature is 70℃, and the electrolysis time is 5h. If the electrolysis is not complete, the impurity removal of tin is not complete, in the subsequent replacement of In, Sn is preferentially replaced into the sponge indium, which affects the product quality, if the amount of electrolytic zinc is too large, In is also replaced during the replacement of Sn, which leads to the increase of the In content in the impurity removal residue, reduces the In yield and increases the recovery cost.

[0025] (3) Electrolytic separation of indium: the filtrate is subjected to micro-current electrolysis again, and the sinking sponge indium at the bottom of the tank is taken; the current density of the micro-current electrolysis is 20A / m 2 , the temperature is 90℃, and the electrolysis time is 10h.

[0026] (4) Pressing, drying: the sinking sponge indium is pressed, dried, and then cast to obtain the finished product. The sponge indium can be cast after being pressed and dried. In the casting process, in order to prevent indium from being oxidized, NaOH is used for covering, and the casting is carried out at 300-400 ℃ for 1-2 h, so that 42.16 g of indium with a grade of about 99.98% can be obtained.

[0027] In the two micro-current electrolysis, the large-size zinc plate is used as the anode, and the small-size titanium plate or stainless steel plate is used as the cathode. Example 2:

[0028] A method for recovering indium from waste target material, comprising the following steps:

[0029] (1) Leaching: 50 g of ITO target waste is added into 1 L of 6 mol / L hydrochloric acid solution, and the pH of the solution is controlled between 2 and 3. Ultrasonic heating is carried out at 80-90 ℃ for 3 h, and then filtration is carried out to obtain tin oxide acid solution residue and leaching solution. In the acid system, SnO2 is stable, which can reduce the reaction dissolution, which is very beneficial to the separation of indium and tin. The power of the ultrasonic wave is 300-800 W. After the addition of ultrasonic wave assistance, the indium leaching rate is above 98.5%, and the tin leaching rate is 30%.

[0030] (2) Electrolytic separation of tin: the leaching solution is placed in an electrolytic tank for micro-current electrolysis, and then filtration is carried out to obtain the filtrate; according to the reaction activity of indium and tin, tin ions are mainly displaced in this step. The current density of micro-current electrolysis is 30 A / m 2 , the temperature is 80 ℃, and the electrolysis time is 4 h. If the electrolysis is not complete, the tin impurity removal is not complete, and in the subsequent replacement of In, Sn is preferentially replaced into the sponge indium, which affects the product quality. If the amount of zinc for electrolysis is too large, In will also be replaced during the replacement of Sn, which will increase the In content in the impurity removal residue, reduce the In yield, and increase the recovery cost.

[0031] (3) Electrolytic separation of indium: the filtrate is subjected to micro-current electrolysis again, and the sinking sponge indium at the bottom of the tank is taken out; the current density of micro-current electrolysis is 30 A / m 2 , the temperature is 80 ℃, and the electrolysis time is 9 h.

[0032] (4) Pressing, drying: the sinking sponge indium is pressed, dried, and then cast to obtain the finished product. The sponge indium can be cast after being pressed and dried. In the casting process, in order to prevent indium from being oxidized, NaOH is used for covering, and the casting is carried out at 300-400 ℃ for 1-2 h, so that 42.16 g of indium with a grade of about 99.98% can be obtained.

[0033] In the two micro-current electrolysis, the large-size zinc plate is used as the anode, and the small-size titanium plate or stainless steel plate is used as the cathode. Example 3:

[0034] A method for recovering indium from waste sputtering targets includes the following steps:

[0035] (1) Leaching: Add 1L of 6mol / L hydrochloric acid solution to 50g of ITO target waste, and control the pH of the solution between 2 and 3. Heat to 80-90℃ under ultrasound, leach for 3h, filter, and obtain stannic acid residue and leachate; SnO2 is stable in acidic system, which can reduce reaction dissolution, which is very beneficial for the separation of indium and tin. The power of ultrasound is 300-800W. After adding ultrasound assistance, the indium leaching rate is above 98.5%, and the tin leaching rate is 30%.

[0036] (2) Electrolytic separation of tin: The leaching solution is placed in an electrolytic cell for micro-current electrolysis, filtered, and the filtrate is collected; according to the reactivity of indium and tin, tin ions are mainly displaced in this step. The current density of micro-current electrolysis is 40 A / m 2 The temperature is 90℃ and the electrolysis time is 3 hours. If the electrolysis is incomplete, the tin impurities will not be completely removed. In the subsequent In replacement process, Sn will be preferentially replaced and enter the sponge indium, affecting product quality. If the amount of zinc electrolyzed is too large, In will also be replaced during Sn replacement, resulting in an increase in the In content in the impurity removal residue, reducing the In yield and increasing the recycling cost.

[0037] (3) Electrolytic separation of indium: The filtrate is subjected to microcurrent electrolysis again, and the indium sponge that has settled at the bottom of the tank is collected; the current density of the microcurrent electrolysis is 40A / m 2 The temperature was 90℃ and the electrolysis time was 6 hours.

[0038] (4) Pressing and drying: The submerged indium sponge is pressed into briquettes, dried, and then melted to obtain the finished product. The indium sponge can be melted after pressing and drying. During the melting and casting process, in order to prevent indium oxidation, it is covered with NaOH. After melting and casting at 300-400 °C for 1-2 hours, about 42.38g of indium with a purity of about 99.98% can be obtained.

[0039] In both microcurrent electrolysis processes, a large zinc plate was used as the anode and a small titanium or stainless steel plate was used as the cathode.

[0040] The above embodiments are merely specific examples to further illustrate the purpose, technical solution, and beneficial effects of the present invention, and the present invention is not limited thereto. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the disclosure of the present invention are included within the protection scope of the present invention.

Claims

1. A method for recovering indium from waste sputtering targets, characterized in that, Includes the following steps: (1) Leaching: Add hydrochloric acid solution to ITO target waste, heat and stir under ultrasonication, leach for a certain time, filter, and obtain acid residue and leachate; (2) Electrolytic separation of tin: The leaching solution is placed in an electrolytic cell for micro-current electrolysis, filtered, and the filtrate is collected; (3) Electrolytic separation of indium: The filtrate is subjected to microcurrent electrolysis again to collect the indium sponge that has settled at the bottom of the tank; (4) Pressing and drying: The submerged indium sponge is pressed into briquettes, dried, and then melted and cast to obtain the finished product; The liquid-to-solid ratio of the ITO target waste to the hydrochloric acid solution is 1g:(20-30)ml, the concentration of the hydrochloric acid solution is 6-7mol / L, and the power of the ultrasound is 300-800W. In both microcurrent electrolysis processes, a large zinc plate was used as the anode and a small titanium or stainless steel plate as the cathode; the current density of the microcurrent electrolysis in step (2) was 20 A / m. 2 ~40A / m 2 The temperature is 70-90℃, and the electrolysis time is 2-3 hours; the current density of the microcurrent electrolysis in step (3) is 20A / m. 2 ~40A / m 2 The temperature is 70–90℃, and the electrolysis time is 6–7 hours.

2. The method for recovering indium from waste sputtering targets according to claim 1, characterized in that: The heating and stirring temperature is 80-90℃, and the leaching time is 3-4 hours.

3. The method for recovering indium from waste sputtering targets according to claim 1, characterized in that: The anode has dimensions of 60×40×0.5cm, and the cathode has dimensions of 30×16×0.5cm.