Method for recovering ITO target material based on molten salt electrolysis

Abstract

The method for recycling the ITO target material based on molten salt electrolysis comprises the steps that a partition plate is arranged at the bottom of an electrolytic bath, and the electrolytic bath is divided into a first area and a second area; a first electrode and a second electrode are arranged in the first area, and a third electrode is arranged in the second area; molten salt electrolyte is arranged in the electrolytic bath, and the liquid level of the molten salt electrolyte is higher than the partition plate; the ITO target material is arranged in the first area, the first electrode is used as an anode, the second electrode is used as a cathode for first electrolysis, and indium tin alloy is generated at the bottom of the electrolytic bath located in the first area; the generated indium tin alloy is in contact with the second electrode; and the second electrode is used as an anode, the third electrode is used as a cathode for secondary electrolysis, the indium-tin alloy is dissolved in the first area, formed metallic tin is left in the first area, and metallic indium is formed on the surface of the third electrode in the second area.

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 targets based on molten salt electrolysis. Background Art

[0002] With the rapid popularization of electronic products in people's lives, a large amount of indium tin oxide (ITO) waste targets are generated every year. ITO targets are the main consumption field of indium metal. Since indium and tin are important metal resources widely used in life, ITO waste targets have great recycling value.

[0003] Currently, 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 treatment cost is high and the reaction process is not easy to control. A large amount of pollutants such as waste acid are generated during the treatment process of the traditional acid leaching method, which is harmful to the human body and the environment. The molten salt electrolysis method usually uses CaCl 2 as the electrolyte to electrochemically recycle ITO waste targets. Due to the underpotential deposition of Ca on the cathode and the treatment temperature of CaCl 2 above 800 °C, the application of the molten salt electrolysis method is not extensive.

[0004] At the same time, the recycled ITO waste targets usually exist as indium tin alloys, and the separation of indium and tin requires further treatment, which increases the complexity of the operation process and also limits the application of indium to a certain extent. Summary of the Invention

[0005] In view of this, the technical solutions disclosed in some embodiments are methods for recycling ITO targets based on molten salt electrolysis, and the methods include:

[0006] A partition is arranged at the bottom of the electrolytic cell to isolate the electrolytic cell into a first zone and a second zone; a first electrode and a second electrode are arranged in the first zone, and a third electrode is arranged in the second zone; a molten salt electrolyte is arranged in the electrolytic cell, and the liquid level of the molten molten salt electrolyte is higher than the partition;

[0007] The ITO target is arranged in the first zone, and the first electrolysis is carried out with the first electrode as the anode and the second electrode as the cathode, and indium tin alloy is generated at the bottom of the electrolytic cell in the first zone; the generated indium tin alloy contacts the second electrode;

[0008] The second electrolysis is carried out with the second electrode as the anode and the third electrode as the cathode. The indium tin alloy dissolves in the first zone, the formed metallic tin remains in the first zone, and metallic indium is formed on the surface of the third electrode in the second zone.

[0009] Further, in the method for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments, the first electrode is a graphite electrode, a titanium electrode, a tungsten electrode or a molybdenum electrode, the second electrode is a titanium electrode, a tungsten electrode or a molybdenum electrode, and the third electrode is a titanium electrode, a tungsten electrode or a molybdenum electrode.

[0010] In the method for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments, the molten salt electrolyte is LiCl, LiF or a LiCl-LiF eutectic salt.

[0011] In the method for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments, the molten salt electrolyte melts at a temperature between 500 and 650 °C, and the heating rate is 5 to 10 °C / min.

[0012] In the method for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments, the second electrode is arranged in contact with the bottom of the electrolytic cell.

[0013] In the method for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments, the height of the partition is greater than the height of the ITO target placed in the first zone.

[0014] In the method for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments, the electrolysis voltage for the first electrolysis is 1.8 to 2.8 V, and the electrolysis time is 1.5 to 6 h.

[0015] In the method for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments, the electrolysis voltage for the second electrolysis is -0.4 to 0.5 V relative to the Pt electrode, and the electrolysis time is 1 to 3 h.

[0016] The method for recycling ITO targets based on molten salt electrolysis disclosed in the embodiments of the present invention realizes the recycling of ITO targets by using two consecutive molten salt electrolysis processes, and at the same time completely separates indium and tin metals. The whole process is efficient, simple to operate, low in energy consumption, environmentally friendly, and has good economic efficiency and practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of an electrolysis device for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments;

[0018] Figure 2 Schematic diagram of an electrolysis device for recycling ITO targets based on molten salt electrolysis disclosed in some embodiments.

[0019] REFERENCE SIGNS

[0020] 1 electrolytic cell 2 first electrode

[0021] 3 second electrode 4 third electrode

[0022] 5 molten salt electrolyte 6 partition

[0023] 7 ITO target 8 Indium tin alloy

[0024] 9 Indium metal 10 Tin metal

[0025] I First zone II Second zone Specific implementation manners

[0026] As used herein, the term "embodiment" in the context of "exemplary", any embodiment so described is not necessarily 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 adopted. It should be understood that the terms described in the embodiments of the present invention are only for describing particular implementation manners and are not intended to limit the content disclosed in the embodiments of the present invention.

[0027] Unless otherwise indicated, the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the technical field to which the embodiments of the present invention belong; other test methods and technical means not specifically noted in the embodiments of the present invention refer to the experimental methods and technical means commonly adopted by one of ordinary skill in the art.

[0028] The terms "substantially" and "about" as used herein 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 herein in a range format are used only for convenience and brevity and should therefore be interpreted flexibly as including not only the values expressly listed as the limits of the range but also all individual values or sub-ranges included within the range. For example, the numerical range of "1 to 5%" should be interpreted as including not only the expressly listed values from 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.

[0029] As used herein, including in the claims, conjunctions such as "comprising", "including", "carrying", "having", "containing", "involving", "accommodating", etc. are to be understood as being open-ended, i.e., meaning "including but not limited to". Only the conjunctions "consisting of" and "composed of" are closed conjunctions.

[0030] To better illustrate 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 also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well-known to those skilled in the art are not described in detail in order to highlight the gist of the present invention.

[0031] 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.

[0032] In some embodiments, the method for recycling ITO targets based on molten salt electrolysis includes:

[0033] A partition is provided at the bottom of the electrolytic cell to isolate the electrolytic cell into a first zone and a second zone; a first electrode and a second electrode are provided in the first zone, and a third electrode is provided in the second zone; a molten salt electrolyte is provided in the electrolytic cell, and the liquid level of the molten molten salt electrolyte is higher than the partition; generally, the first electrode is a graphite electrode, a titanium electrode, a tungsten electrode or a molybdenum electrode, the second electrode is a titanium electrode, a tungsten electrode or a molybdenum electrode, and the third electrode is a titanium electrode, a tungsten electrode or a molybdenum electrode; the molten salt electrolyte is LiCl, LiF or a LiCl-LiF eutectic salt; the height of the partition is greater than the height of the ITO target placed in the first zone to confine the ITO target in the first zone and prevent it from entering the second zone;

[0034] The ITO target is arranged in the first zone, and the first electrolysis is carried out with the first electrode as the anode and the second electrode as the cathode. The molten salt electrolyte is heated to between 500 and 650 °C for melting, and the heating rate is 5 to 10 °C / min. Generally, the first electrolysis is a constant voltage electrolysis, and the voltage is 1.8 to 2.8 V. After electrolysis for 3 to 6 h, an indium-tin alloy is formed at the bottom of the electrolytic cell in the first zone; the formed indium-tin alloy is in contact with the second electrode;

[0035] The second electrolysis is carried out with the second electrode as the anode and the third electrode as the cathode. The second electrolysis is a constant voltage electrolysis, and the electrolysis voltage is -0.4 to 0.5 V (compared with the Pt electrode), and the electrolysis time is 1 to 3 h; the indium-tin alloy dissolves in the first zone, the formed metallic tin remains in the first zone, and metallic indium is formed on the surface of the third electrode in the second zone.

[0036] Generally, LiCl or LiF or a LiCl-LiF eutectic salt is used as the molten salt electrolyte. First, the first electrolysis is carried out to electrolytically recover the ITO waste target. After obtaining the indium-tin alloy, the second electrolysis is carried out to electrolytically separate the indium-tin alloy. Compared with tin metal, indium metal is more active. Therefore, indium metal is obtained on the cathode of the second electrolysis.

[0037] In some embodiments, a method for recycling ITO targets based on molten salt electrolysis is disclosed. The second electrode is arranged in contact with the bottom of the electrolytic cell so that the generated indium-tin alloy can be in good contact with the second electrode.

[0038] The following further exemplarily illustrates the technical details in conjunction with embodiments.

[0039] Example 1

[0040] In Example 1, the method for recycling ITO targets based on molten salt electrolysis is carried out in the Figure 1 shown device, including:

[0041] A vertically arranged partition 6 is provided at the bottom of the electrolytic cell 1 to isolate the electrolytic cell 1 into a first zone I and a second zone II; a first electrode 2 and a second electrode 3 are arranged in the first zone I, and a third electrode 4 is arranged in the second zone II; a molten salt electrolyte 5 is arranged in the electrolytic cell 1, and the liquid level of the molten molten salt electrolyte 5 is higher than the partition 6; the first electrode 2 is a graphite electrode, the second electrode 3 is a titanium electrode, and the third electrode 4 is a molybdenum electrode; the molten salt electrolyte 5 is a LiCl-LiF eutectic salt;

[0042] The ITO target is arranged in the first zone. With the first electrode 2 as the anode and the second electrode 3 as the cathode, the first electrolysis is carried out. The molten salt electrolyte is heated to 500 °C for melting at a heating rate of 5 °C / min and kept warm for 1 h; the electrolysis voltage is 1.8 V. After electrolysis for 1.5 h, an indium-tin alloy 8 is generated at the bottom of the first zone of the electrolytic cell; the generated indium-tin alloy 8 is in contact with the second electrode 3;

[0043] With the second electrode 3 as the anode and the third electrode 4 as the cathode, the second electrolysis is carried out. The electrolysis voltage is -0.4 V (reference Pt electrode); electrolysis is carried out for 1.5 h. As Figure 2 shown, the indium-tin alloy dissolves in the first zone, the formed metallic tin 10 remains in the first zone, and metallic indium 9 is formed on the surface of the third electrode 4 in the second zone.

[0044] The current efficiency of Example 1 is 43%.

[0045] The current efficiency is calculated according to the following formula:

[0046] m = I·t / F·Z·M (1)

[0047] η = m1 / m (2)

[0048] Wherein, m and m1 are respectively the theoretical mass and the actual mass of the electrolysis product, 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.

[0049] Example 2

[0050] In Example 2, the method for recycling ITO target based on molten salt electrolysis was carried out with reference to Example 1;

[0051] Among them, the first electrode is a titanium plate, the second electrode is a molybdenum rod, and the third electrode is a molybdenum rod; the heating temperature of the electrolyte LiCl-LiF eutectic salt is 550 °C, the first electrolysis time is 2 h, and the electrolysis voltage is 2.0 V; the second electrolysis time is 2 h, and the electrolysis voltage is -0.4 V (reference Pt electrode);

[0052] The current efficiency of Example 2 is 49%.

[0053] Example 3

[0054] In Example 3, the method for recycling ITO target based on molten salt electrolysis was carried out with reference to Example 1;

[0055] Among them, the first electrode is a tungsten rod, the second electrode is a tungsten rod, and the third electrode is a molybdenum rod; the heating temperature of the electrolyte LiCl-LiF eutectic salt is 600 °C, the first electrolysis time is 2 h, and the electrolysis voltage is 2.4 V; the second electrolysis time is 3 h, and the electrolysis voltage is -0.4 V (reference Pt electrode);

[0056] The current efficiency of Example 3 is 54%.

[0057] Example 4

[0058] In Example 4, the method for recycling ITO target based on molten salt electrolysis was carried out with reference to Example 1;

[0059] Among them, the first electrode is a graphite rod, the second electrode is a tungsten rod, and the third electrode is a molybdenum rod; the heating temperature of the electrolyte LiCl-LiF eutectic salt is 650 °C, the first electrolysis time is 3 h, and the electrolysis voltage is 2.8 V; the second electrolysis time is 2 h, and the electrolysis voltage is -0.4 V (reference Pt electrode);

[0060] The current efficiency of Example 4 is 59%.

[0061] Example 5

[0062] In Example 5, the method for recycling ITO target based on molten salt electrolysis was carried out with reference to Example 1;

[0063] Among them, the first electrode is a graphite rod, the second electrode is a molybdenum rod, and the third electrode is a titanium plate; the heating temperature of the electrolyte LiCl-LiF eutectic salt is 600 °C, the first electrolysis time is 3 h, and the electrolysis voltage is 1.8 V; the second electrolysis time is 1 h, and the electrolysis voltage is -0.5 V (reference Pt electrode).

[0064] The current efficiency of Example 5 is 63%.

[0065] Example 6

[0066] In Example 6, the method for recycling ITO target by molten salt electrolysis was carried out with reference to Example 1;

[0067] Among them, the first electrode is a titanium plate, the second electrode is a titanium plate, and the third electrode is a titanium plate; the heating temperature of the electrolyte LiCl-LiF eutectic salt is 650 °C, the first electrolysis time is 2 h, and the electrolysis voltage is 2.0 V; the second electrolysis time is 1.5 h, and the electrolysis voltage is -0.5 V (reference Pt electrode).

[0068] The current efficiency of Example 6 is 70%.

[0069] Example 7

[0070] In Example 7, the method for recycling ITO target by molten salt electrolysis was carried out with reference to Example 1;

[0071] Among them, the first electrode is a graphite rod, the second electrode is a molybdenum rod, and the third electrode is a molybdenum rod; the heating temperature of the electrolyte LiCl-LiF eutectic salt is 650 °C, the first electrolysis time is 3 h, and the electrolysis voltage is 2.4 V; the second electrolysis time is 3 h, and the electrolysis voltage is -0.5 V (reference Pt electrode).

[0072] The current efficiency of Example 7 is 68%.

[0073] Example 8

[0074] In Example 8, the method for recycling ITO target by molten salt electrolysis was carried out with reference to Example 1;

[0075] Among them, the first electrode is a tungsten rod, the second electrode is a titanium plate, and the third electrode is a molybdenum rod; the heating temperature of the electrolyte LiCl-LiF eutectic salt is 550 °C, the first electrolysis time is 1.5 h, and the electrolysis voltage is 2.8 V; the second electrolysis time is 1.5 h, and the electrolysis voltage is -0.5 V (reference Pt electrode).

[0076] The current efficiency of Example 8 is 67%.

[0077] The method for continuously recycling ITO waste target and separating indium and tin by molten salt electrolysis disclosed in the embodiments of the present invention uses LiCl or LiF or LiCl-LiF eutectic salt to first electrolytically recycle the ITO waste target. After obtaining the indium-tin alloy, the indium-tin alloy is electrolytically separated. Compared with tin metal, indium metal is more active. Therefore, indium metal is obtained on the secondary cathode. The method for continuously recycling ITO waste target and separating indium and tin by molten salt electrolysis disclosed in the embodiments of the present invention has high separation efficiency of indium and tin, simple operation process, low energy consumption, environmental friendliness, and good economy.

[0078] The technical solutions disclosed in the embodiments of the present invention and the technical details disclosed in the embodiments 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, combinations, etc. 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 scope of protection of the claims of the present invention.

Claims

1. A method for recovering ITO target material based on molten salt electrolysis, characterized in that: include: A partition is arranged at the bottom of the electrolytic cell to separate the electrolytic cell into a first zone and a second zone; a first electrode and a second electrode are arranged in the first zone, and a third electrode is arranged in the second zone; a molten salt electrolyte is arranged in the electrolytic cell, and a liquid level of the molten salt electrolyte is higher than the partition; The ITO target is arranged in the first zone, and the first electrolysis is performed with the first electrode as the anode and the second electrode as the cathode, so that an indium tin alloy is generated at the bottom of the electrolytic cell located in the first zone; the generated indium tin alloy is in contact with the second electrode; The second electrolysis is performed with the second electrode as the anode and the third electrode as the cathode. The indium tin alloy is dissolved in the first zone, the formed metal tin remains in the first zone, and metal indium is formed on the surface of the third electrode in the second zone.

2. The method for recovering ITO target material based on molten salt electrolysis according to claim 1, characterized in that: The first electrode is a graphite electrode, a titanium electrode, a tungsten electrode or a molybdenum electrode, the second electrode is a titanium electrode, a tungsten electrode or a molybdenum electrode, and the third electrode is a titanium electrode, a tungsten electrode or a molybdenum electrode.

3. The method for recovering ITO target material based on molten salt electrolysis according to claim 1, characterized in that: The molten salt electrolyte is LiCl, LiF or LiCl-LiF eutectic salt.

4. The method for recovering ITO target material based on molten salt electrolysis according to claim 1, characterized in that: The molten salt electrolyte melts at a temperature between 500 and 650°C, and the heating rate is 5 to 10°C / min.

5. The method for recovering ITO target material based on molten salt electrolysis according to claim 1, characterized in that: The second electrode is arranged in contact with the bottom of the electrolytic cell.

6. The method for recovering ITO target material based on molten salt electrolysis according to claim 1, characterized in that: The height of the partition is greater than the height of the ITO target placed in the first area.

7. The method for recovering ITO target material based on molten salt electrolysis according to claim 1, characterized in that: The electrolysis voltage of the first electrolysis is 1.8-2.8V, and the electrolysis time is 1.5-6h.

8. The method for recovering ITO target material based on molten salt electrolysis according to claim 1, characterized in that: The electrolysis voltage of the second electrolysis is -0.4 to 0.5 V compared to the Pt electrode, and the electrolysis time is 1 to 3 hours.

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