Method for recycling ITO (indium tin oxide) based on low-temperature molten salt electrolysis

Abstract

The embodiment of the invention discloses a method for recycling ITO based on low-temperature molten salt electrolysis. The method comprises the steps that a low-temperature molten salt electrolyte is arranged in an electrolytic bath; the low-temperature molten salt electrolyte comprises NaOH (sodium hydroxide), KOH (potassium hydroxide), LiOH (lithium hydroxide), NaOH-KOH (potassium hydroxide), NaOH-LiOH (lithium hydroxide), KOH-LiOH (potassium hydroxide) or NaOH-KOH-LiOH (potassium hydroxide); the inert metal crucible is arranged in the electrolytic bath and serves as a cathode; the inert electrode is arranged in the electrolytic bath as an anode; the ITO sputtering target material is placed in the inert metal crucible; and the low-temperature molten electrolyte is heated to a set temperature for electrolysis, and the ITO sputtering target material in the inert metal crucible is converted into the indium tin alloy. According to the method for recycling the ITO based on electrolysis of the low-temperature molten salt, the low-temperature molten salt serves as the electrolyte, under the action of charges, deoxidation of the ITO on the cathode is achieved, meanwhile, electro-deposition of indium and tin is achieved, the indium and tin recycling speed is high, the operation process is simple, energy consumption is low, environment friendliness is achieved, and good economical efficiency and practicability are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sputtering target recycling, and particularly relates to a method for recycling ITO based on low-temperature molten salt electrolysis. Background Art

[0002] The ITO target is composed of 90wt% In2O3 and 10wt% SnO2, which is the main consumption field of indium metal, accounting for 70% of the global indium consumption. With the rapid popularization of electronic products in people's lives, the demand for ITO targets is also increasing. A large amount of ITO waste targets will be generated during the processing and use of ITO. These are valuable secondary resources with great recycling potential and are a potential treasure trove of indium metal.

[0003] At present, the main methods for recycling ITO waste targets are thermal reduction method, acid leaching method and molten salt electrolysis method. The thermal reduction method has a high recovery rate and low energy consumption, but the processing cost is high and the reaction process is not easy to control. The traditional acid leaching method for recycling ITO waste targets has the disadvantages of complex process, low efficiency and generation of pollutants. As a favored green recycling technology, the molten salt electrolysis method can be applied to the recycling of waste ITO. However, CaCl2 is usually used as the deoxidizing electrolyte, which not only causes partial deposition of Ca metal on the cathode product, but also requires the CaCl2 molten salt to be at a high temperature above 800 °C, resulting in energy loss.

[0004] Therefore, it is particularly important to develop a method for recycling ITO waste targets that is efficient, low-energy-consuming and harmless to the environment and human body. Summary of the Invention

[0005] In view of this, the technical solutions disclosed in some embodiments are a method for recycling ITO based on low-temperature molten salt electrolysis, including:

[0006] A low-temperature molten salt electrolyte is provided in the electrolytic cell; the low-temperature molten salt electrolyte includes NaOH, KOH, LiOH, NaOH-KOH, NaOH-LiOH, KOH-LiOH or NaOH-KOH-LiOH;

[0007] An inert metal crucible is arranged in the electrolytic cell as the cathode;

[0008] An inert electrode is arranged in the electrolytic cell as the anode;

[0009] The ITO sputtering target is placed in the inert metal crucible;

[0010] The low-temperature molten electrolyte is heated to a set temperature for electrolysis, and the ITO sputtering target in the inert metal crucible is converted into an indium-tin alloy.

[0011] Furthermore, in the method for recycling ITO based on low-temperature molten salt electrolysis disclosed in some embodiments, the inert metal crucible serving as the cathode is located below the liquid level of the low-temperature molten salt electrolyte.

[0012] In the method for recycling ITO based on low-temperature molten salt electrolysis disclosed in some embodiments, the low-temperature metal crucible includes a molybdenum crucible or a tungsten crucible, and the inert electrode includes a graphite electrode, a molybdenum electrode, or a tungsten electrode.

[0013] In the method for recycling ITO based on low-temperature molten salt electrolysis disclosed in some embodiments, the set temperature is 170 - 300 °C.

[0014] In the method for recycling ITO based on low-temperature molten salt electrolysis disclosed in some embodiments, the electrolysis time is set to 1.5 - 3 h, and the electrolysis voltage is set to 1.5 - 3 V.

[0015] In the method for recycling ITO based on low-temperature molten salt electrolysis disclosed in some embodiments, the mass ratio of the ITO sputtering target to the low-temperature molten salt electrolyte is 1:25 - 100.

[0016] The method for recycling ITO based on low-temperature molten salt electrolysis disclosed in the embodiments of the present invention uses low-temperature molten salt as the electrolyte. Under the action of electric charges, deoxidation of ITO on the cathode is achieved, and at the same time, electrodeposition of indium and tin is realized. The recovery speed of indium and tin is fast, the operation process is simple, the energy consumption is low, it is environmentally friendly, and it has good economic efficiency. Description of the Drawings

[0017] Figure 1 Schematic diagram of the device for recycling ITO based on low-temperature molten salt electrolysis in Example 1.

[0018] Reference Signs

[0019] 1 Anode 2 Cathode

[0020] 3 Waste ITO 4 Electrolyte

[0021] 5 Electrolytic Cell 6 Indium-Tin Alloy Detailed Embodiments

[0022] The special term "embodiment" here, any embodiment described as "exemplary" does not have to be construed as superior to or better than other embodiments. For the performance index tests in the embodiments of the present invention, unless otherwise specified, conventional test methods in the art are used. It should be understood that the terms described in the embodiments of the present invention are only for describing specific embodiments and are not used to limit the content disclosed in the embodiments of the present invention.

[0023] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the technical field to which the embodiments of the present invention pertain; other test methods and technical means not specifically noted in the embodiments of the present invention refer to the test methods and technical means commonly adopted by those of ordinary skill in the art.

[0024] As used herein, the terms "substantially" and "about" are used to describe minor fluctuations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or represented herein in a range format are used only for convenience and brevity, and should therefore be interpreted flexibly to include not only the values explicitly recited as the bounds of the range, but also all individual values or sub-ranges subsumed within that range. For example, a numerical range of "1 to 5%" should be interpreted to include not only the explicitly recited values of 1% to 5%, but also the individual values and sub-ranges within the indicated range. Thus, within this numerical range, individual values such as 2%, 3.5%, and 4% are included, and sub-ranges such as 1% to 3%, 2% to 4%, and 3% to 5% are included, etc. This principle also applies to ranges that list only one numerical value. In addition, such an interpretation applies regardless of the width of the range or the characteristics described.

[0025] In this document, including in the claims, conjunctions such as "comprising", "including", "carrying", "having", "containing", "involving", "accommodating", etc. are understood to be open-ended, that is, meaning "including but not limited to". Only the conjunctions "consisting of" and "composed of" are closed conjunctions.

[0026] For a better illustration of the content of the present invention, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present invention can be implemented without some of these specific details. In the embodiments, some methods, means, instruments, devices, etc. well-known to those skilled in the art are not described in detail in order to highlight the gist of the present invention.

[0027] On the premise of no conflict, the technical features disclosed in the embodiments of the present invention can be combined arbitrarily, and the obtained technical solutions belong to the content disclosed in the embodiments of the present invention.

[0028] In some embodiments, the method for recycling ITO based on low-temperature molten salt electrolysis includes:

[0029] A low-temperature molten salt electrolyte is provided in the electrolytic cell; the low-temperature molten salt electrolyte includes NaOH, KOH, LiOH, NaOH-KOH, NaOH-LiOH, KOH-LiOH, or NaOH-KOH-LiOH;

[0030] An inert metal crucible is disposed in the electrolytic cell and serves as the cathode; generally, the inert metal crucible serving as the cathode is located below the liquid level of the low-temperature molten salt electrolyte disposed in the electrolytic cell; generally, the low-temperature metal crucible includes a molybdenum crucible or a tungsten crucible; generally, the inert metal crucible refers to a metal crucible that only serves as a conductor and does not participate in other electrochemical reaction processes in the embodiments of the present invention;

[0031] An inert electrode is disposed in the electrolytic cell and serves as the anode; generally, the inert electrode includes a graphite electrode, a molybdenum electrode or a tungsten electrode; generally, the inert electrode refers to an electrode that only serves as a conductor and does not participate in other electrochemical reaction processes in the embodiments of the present invention;

[0032] The ITO sputtering target is placed in the inert metal crucible; generally, the mass ratio of the ITO sputtering target to the low-temperature molten salt electrolyte is 1:25 to 100;

[0033] The low-temperature molten electrolyte is heated to a set temperature for electrolysis. The set temperature is 170 to 300 °C, the electrolysis time is set to 1.5 to 3 h, and the electrolysis voltage is set to 1.5 to 3 V. The ITO sputtering target in the inert metal crucible is converted into indium tin alloy.

[0034] For the method for recycling ITO based on low-temperature molten salt electrolysis, the electrolysis current efficiency is 40 to 65%, and the comprehensive product yield is 97 to 99.9%.

[0035] Among them, the comprehensive product yield = (mass of cathode product) ÷ (mass consumed at the anode × content of indium in indium oxide ÷ molecular weight of indium oxide) × 100%.

[0036] The current efficiency is calculated according to the following formula:

[0037] m = I·t / F·Z·M

[0038] η = m1 / m

[0039] Among them, m and m1 are the theoretical mass and actual mass of the electrolytic product respectively, with the unit of g; I represents the current, in A; t is the electrolysis time, in s; M is the atomic mass; F is the Faraday constant, 96485 C·mol -1 ; Z represents the number of moles of transferred electrons, and η is the current efficiency, in %.

[0040] For the method for recycling ITO based on low-temperature molten salt electrolysis disclosed in the embodiments of the present invention, by using the low-temperature molten salt as the electrolyte, under the action of charge, deoxidation of ITO on the cathode is achieved, and at the same time, electrodeposition of indium and tin is realized. The indium and tin recovery speed is fast, the operation process is simple, the energy consumption is low, it is environmentally friendly, and it has good economic efficiency.

[0041] The following further exemplarily illustrates the technical details in combination with the embodiments.

[0042] Example 1

[0043] In Example 1, the method for electrolytic recovery of ITO is carried out in the device shown in Figure 1 and includes:

[0044] A low-temperature molten salt electrolyte 4 is provided in the electrolytic cell 5; the low-temperature molten salt electrolyte is NaOH-LiOH;

[0045] An inert metal crucible is arranged in the electrolytic cell 5 and serves as the cathode 2; the inert metal crucible is a molybdenum crucible;

[0046] An inert electrode is arranged in the electrolytic cell and serves as the anode 1; the inert electrode is a graphite electrode;

[0047] The ITO sputtering target 3 is placed in the inert metal crucible in the form of fragments; the ratio of the ITO sputtering target to the low-temperature molten salt electrolyte is 1:50;

[0048] The low-temperature molten electrolyte is heated to the set temperature of 170 °C at a heating rate of 5 °C / min and kept warm for 1 h, and then electrolysis is carried out. The electrolysis voltage is 1.5 V and the electrolysis time is 1.5 h. The ITO sputtering target in the inert metal crucible is converted into indium tin alloy 6;

[0049] In Example 1, the overall product yield is 96.2% and the current efficiency is 42%.

[0050] Example 2

[0051] In Example 2, the method for electrolytic recovery of ITO is carried out with reference to Example 1;

[0052] Among them, the anode is a graphite electrode, the cathode is a tungsten crucible, the set temperature is 200 °C, the heat preservation time is 1.5 h, the electrolysis voltage is 1.8 V, and the electrolysis time is 1.5 h.

[0053] In Example 2, the overall product yield is 97.2% and the electrolysis efficiency is 49%.

[0054] Example 3

[0055] In Example 3, the method for electrolytic recovery of ITO is carried out with reference to Example 1;

[0056] Among them, the anode is a graphite electrode, the cathode is a molybdenum crucible, the low-temperature molten salt electrolyte is LiOH-KOH, the set temperature is 200 °C, the electrolysis voltage is 2.2 V, and the electrolysis time is 2 h.

[0057] In Example 3, the overall product yield is 98.2% and the electrolysis efficiency is 52%.

[0058] Example 4

[0059] In Example 4, the method for electrolytic recovery of ITO was carried out with reference to Example 1;

[0060] Among them, the anode was a graphite electrode, the cathode was a molybdenum crucible, the low-temperature molten salt electrolyte was NaOH, the ratio of the ITO sputtering target to the low-temperature molten salt electrolyte was 1:100, the set temperature was 250 °C, the heat preservation time was 1.5 h, the electrolysis voltage was 2.6 V, and the electrolysis time was 2 h.

[0061] In Example 4, the comprehensive product yield was 98.6%, and the electrolysis efficiency was 55%.

[0062] Example 5

[0063] In Example 5, the method for electrolytic recovery of ITO was carried out with reference to Example 1;

[0064] Among them, the anode was a graphite electrode, the cathode was a molybdenum crucible, the low-temperature molten salt electrolyte was NaOH-KOH-LiOH, the ratio of the ITO sputtering target to the low-temperature molten salt electrolyte was 1:25, the set temperature was 300 °C, the heating rate was 10 °C / min, the electrolysis voltage was 3 V, and the electrolysis time was 3 h.

[0065] In Example 5, the comprehensive product yield was 99.2%, and the electrolysis efficiency was 63%.

[0066] Example 6

[0067] In Example 6, the method for electrolytic recovery of ITO was carried out with reference to Example 1;

[0068] Among them, the anode was a graphite electrode, the cathode was a molybdenum crucible, the low-temperature molten salt electrolyte was KOH, the ratio of the ITO sputtering target to the low-temperature molten salt electrolyte was 1:100, the electrolysis voltage was 2.2 V, and the electrolysis time was 3 h.

[0069] In Example 6, the comprehensive product yield was 98.2%, and the electrolysis efficiency was 49%.

[0070] Example 7

[0071] In Example 7, the method for electrolytic recovery of ITO was carried out with reference to Example 1;

[0072] Among them, the anode was a molybdenum electrode, the cathode was a molybdenum crucible, the low-temperature molten salt electrolyte was KOH-NaOH, the ratio of the ITO sputtering target to the low-temperature molten salt electrolyte was 1:25, the set temperature was 250 °C, the heating rate was 10 °C / min, the electrolysis voltage was 2.4 V, and the electrolysis time was 2 h.

[0073] In Example 7, the comprehensive product yield was 98.5%, and the electrolysis efficiency was 56%.

[0074] Example 8

[0075] In Example 8, the method for electrolytic recovery of ITO was carried out with reference to Example 1;

[0076] Among them, the anode was a molybdenum electrode, the cathode was a molybdenum crucible, the low-temperature molten salt electrolyte was KOH-NaOH, the ratio of the ITO sputtering target to the low-temperature molten salt electrolyte was 1:100, the set temperature was 250 °C, the electrolysis voltage was 2.8 V, and the electrolysis time was 2 h.

[0077] In Example 8, the comprehensive yield of the product was 98.7%, and the electrolysis efficiency was 58%.

[0078] The method for electrolytic recovery of ITO based on low-temperature molten salt disclosed in the embodiments of the present invention uses low-temperature molten salt as the electrolyte. Under the action of electric charge, the deoxidation of ITO on the cathode is realized, and at the same time, the electrodeposition of indium and tin is realized. The recovery speed of indium and tin is fast, the operation process is simple, the energy consumption is low, it is environmentally friendly, and it has good economy and practicability.

[0079] The technical solutions disclosed in the embodiments of the present invention and the technical details disclosed in the examples are only exemplary illustrations of the inventive concept of the present invention, and do not constitute a limitation on the technical solutions of the embodiments of the present invention. Any conventional changes, substitutions or combinations made to the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the protection scope of the claims of the present invention.

Claims

1. A method for recovering ITO based on low-temperature molten salt electrolysis, characterized in that: include: A low-temperature molten salt electrolyte is arranged in the electrolytic cell, wherein the low-temperature molten salt electrolyte comprises NaOH, KOH, LiOH, NaOH-KOH, NaOH-LiOH, KOH-LiOH or NaOH-KOH-LiOH; An inert metal crucible is placed in the electrolytic cell and serves as the cathode; An inert electrode is placed in the electrolytic cell and serves as the anode; The ITO sputtering target is placed in an inert metal crucible; The low-temperature molten electrolyte is heated to a set temperature and electrolysis is performed, and the ITO sputtering target in the inert metal crucible is converted into an indium tin alloy.

2. The method for recovering ITO based on low-temperature molten salt electrolysis according to claim 1, characterized in that: An inert metal crucible, which serves as the cathode, is located below the surface of a low-temperature molten salt electrolyte.

3. The method for recovering ITO based on low-temperature molten salt electrolysis according to claim 1, characterized in that: The low-temperature metal crucible includes a molybdenum crucible or a tungsten crucible, and the inert electrode includes a graphite electrode, a molybdenum electrode or a tungsten electrode. 4 . The method for recovering ITO based on low-temperature molten salt electrolysis according to claim 1 , wherein the set temperature is 170 to 300° C.

5. According to the method for recovering ITO based on low-temperature molten salt electrolysis according to claim 1, the electrolysis time is set to 1.5 to 3 hours, and the electrolysis voltage is set to 1.5 to 3V.

6. The method for recovering ITO based on low-temperature molten salt electrolysis according to claim 1, characterized in that: The mass ratio of ITO sputtering target to low-temperature molten salt electrolyte is 1:25-100.

7. The method for recovering ITO based on low-temperature molten salt electrolysis according to claim 1, characterized in that: The electrolysis current efficiency is 40-65%.

8. The method for recovering ITO based on low-temperature molten salt electrolysis according to claim 1, characterized in that: The comprehensive yield of the product is 97-99.9%.

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