ITO waste target recovery method

Abstract

The invention provides an ITO waste target recovery method. The ITO waste target recovery method comprises the following steps: mixing an ITO waste target, sulfur and graphite to obtain a mixture; placing the mixture in an inert environment, heating the mixture to 300-430 DEG C, and carrying out a vulcanization reaction to obtain an intermediate after the reaction is finished; heating the intermediate to 1100-1200 DEG C under a first pressure, and obtaining a mixed gas containing indium sulfide and tin sulfide after the reaction is finished; under second pressure intensity, placing the mixed gas containing indium sulfide and tin sulfide at the temperature of 800-850 DEG C, and respectively obtaining condensed indium sulfide and gas containing tin sulfide after the reaction is finished; and placing the gas containing tin sulfide at a temperature of 550-650 DEG C under a third pressure intensity, and obtaining condensed tin sulfide after the reaction is finished. The method provided by the invention is environment-friendly, and the ITO waste target can be recycled to prepare the high-purity indium sulfide.

Description

Technical Field

[0001] The invention relates to the field of ITO waste target recycling, and more particularly to a method for recycling ITO waste targets. Background Art

[0002] Indium tin oxide (ITO), a strategic functional material with excellent conductivity and optical transparency, holds an irreplaceable position in the field of flat panel displays. However, its entire industry chain faces significant resource efficiency bottlenecks: the sintering process produces approximately 15-20% of scrap, and the magnetron sputtering process suffers from severe losses. The actual utilization rate of target materials is generally less than 30%, and more than 70% of ITO is deposited in the vacuum chamber as coating waste, directly leading to the strategic loss of precious metal indium. According to international metal statistics, global indium reserves are only 16,000 tons, and annual consumption is increasing by more than 8%. The imbalance between supply and demand has caused a sharp rise in indium prices in the past decade, and resource sustainability faces severe challenges.

[0003] The two main methods for recycling waste ITO targets are hydrothermal and solvothermal. These traditional methods offer high metal leaching rates and can selectively dissolve indium and tin by adjusting the solvent system (water is used as the medium for the hydrothermal method, while organic solvents are used for the solvothermal method). However, their drawbacks include the high cost of organic solvent recovery and potential toxic residues in the hydrothermal method.

[0004] Developing new recycling technologies that are both economical and process-clean has become a common demand in the industry. Summary of the Invention

[0005] In view of the shortcomings of the prior art, one of the objectives of the present invention is to solve one or more problems existing in the prior art. For example, one of the objectives of the present invention is to provide a method for recycling waste ITO targets to prepare high-purity indium sulfide.

[0006] One aspect of the present invention provides a method for recycling waste ITO targets, which can include the following steps: mixing the waste ITO targets, sulfur and graphite to obtain a mixture; placing the mixture in an inert environment, heating it to 300°C to 430°C for a sulfurization reaction, and obtaining an intermediate after the reaction; heating the intermediate to 1100°C to 1200°C under a first pressure, and obtaining a mixed gas containing indium sulfide and tin sulfide after the reaction; placing the mixed gas containing indium sulfide and tin sulfide at a temperature of 800°C to 850°C under a second pressure, and obtaining condensed indium sulfide and a gas containing tin sulfide after the reaction; and placing the gas containing tin sulfide at a temperature of 550°C to 650°C under a third pressure, and obtaining condensed tin sulfide after the reaction.

[0007] Furthermore, the first pressure, the second pressure and the third pressure may be 8Pa to 12Pa.

[0008] Furthermore, after the intermediate is heated to 1100° C. to 1200° C., the temperature can be kept at 1.5 to 2.5 hours until the reaction is completed, thereby obtaining a mixed gas containing indium sulfide and tin sulfide.

[0009] Furthermore, the mixed gas containing indium sulfide and tin sulfide is placed at a temperature of 800° C. to 850° C. and kept warm for 1.5 h to 2.5 h until the reaction is completed, thereby obtaining condensed indium sulfide and tin sulfide-containing gas, respectively.

[0010] Furthermore, the gas containing tin sulfide is placed at a temperature of 550° C. to 650° C. and kept at this temperature for 1.5 hours to 2.5 hours until the reaction is completed, thereby obtaining condensed tin sulfide.

[0011] Furthermore, the intermediate may be an In2S3 / In4SnS8 composite material composed of In2S3 and In4SnS8 and having a heterojunction structure.

[0012] Furthermore, after the reaction of the tin sulfide-containing gas at a temperature of 550° C. to 650° C. is completed, the system pressure can be maintained above 20 Pa to obtain condensed tin sulfide.

[0013] Compared with the prior art, the beneficial effects of the present invention include at least:

[0014] The present invention proposes a normal pressure sulfurization-vacuum distillation process, in which a waste ITO target is subjected to a sulfurization reaction under normal pressure conditions, and then the indium sulfide, tin sulfide and other impurities obtained by the sulfurization are separated by vacuum distillation and graded condensation. After separation, 4N indium sulfide and 2N tin sulfide can be obtained, which solves the problem that high-purity indium sulfide is difficult to prepare by current hydrothermal methods, solvothermal methods, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects and features of the present invention will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0016] Figure 1 Schematic diagram of the ITO waste target recovery device.

[0017] Figure 2 This is the TEM image of the intermediate prepared in Example 1.

[0018] Description of reference numerals:

[0019] 1 - Argon cylinder, 2 - Flow meter, 3 - Pressure gauge, 4 - Quartz tube, 5 - Graphite boat, 6 - Heating element, 7 - Insulating material, 8 - Thermocouple, 9 - Graphite paper, 10 - Flange ring, 11 - Control cabinet, 12 - Vacuum pump, 13 - Filter tank, 14 - Bellows, 15 - Cold water tank, 16 - Gas washing bottle, 17 - Safety bottle, 18 - Gas washing bottle. DETAILED DESCRIPTION

[0020] Hereinafter, an ITO waste target recovery method according to the present application will be described in detail in conjunction with the accompanying drawings and exemplary embodiments.

[0021] The present application provides an ITO waste target recovery method. In some embodiments, the following steps can be included:

[0022] Step 01, mixing ITO waste target, sulfur and graphite to obtain a mixture.

[0023] Step 02, placing the mixture in an inert environment, heating to 300-430°C for vulcanization reaction, and obtaining an intermediate after the reaction is completed.

[0024] Step 03, heating the intermediate to 1100-1200°C under a first pressure, and obtaining a mixed gas containing indium sulfide and tin sulfide after the reaction is completed.

[0025] Step 04, placing the mixed gas containing indium sulfide and tin sulfide at a temperature of 800-850°C under a second pressure, and obtaining condensed indium sulfide and a gas containing tin sulfide after the reaction is completed, respectively.

[0026] Step 05, placing the gas containing tin sulfide at a temperature of 550-650°C under a third pressure, and obtaining condensed tin sulfide after the reaction is completed.

[0027] In some embodiments, the amount of sulfur can be equal to or greater than the amount of the ITO waste target, and the amount of sulfur added can ensure that the indium and tin elements in the waste target are completely sulfidized to form In2S3and In4SnS8. The graphite is added to the mixture to react with the oxygen elements in the ITO to generate CO and / or CO2, which removes the oxygen elements from the system in gaseous form, avoids the formation of indium oxide (In2O3), helps to increase the content of indium tin sulfide in the product, and avoids the generation of indium oxide, which increases the process of removing indium oxide, and helps to improve the purity of indium sulfide and tin sulfide. The amount of graphite added can be sufficient to consume the oxygen elements in the ITO. However, the amount of graphite should be controlled to be no more than 10% of the amount of the ITO waste target, and excessive graphite will remain in the product and cannot be removed, which will cause the related performance of the product to decrease. In some embodiments, the amount of graphite added can be in the range of 4% to 10%, 5% to 9%, 6% to 8%, or a combination thereof, of the amount of the ITO waste target. In some embodiments, the graphite can be graphite powder, and the sulfur can be sublimed sulfur.

[0028] In some embodiments, in order to strengthen the sulfidation reaction, the mixture of the ITO waste target, sulfur, and graphite can be subjected to a pore-forming treatment. The pore-forming method can include: after the mixture is thoroughly mixed, a pore-forming agent is added, and after drying, a mixture with a large number of voids on the surface and inside is obtained. For example, the ITO waste target, sulfur, and graphite can be thoroughly stirred and mixed in a graphite boat, and about 1 / 4 of the total mass of anhydrous ethanol as a pore-forming agent can be added during stirring. Subsequently, the crucible is placed in a forced air drying oven and dried at 90°C for 40 minutes, and the evaporation of alcohol can cause a large number of voids on the surface and inside of the mixture.

[0029] In some embodiments, the sulfidation reaction temperature can be controlled to be in the range of 300°C to 430°C. At the above sulfidation reaction temperature, the graphite can consume the oxygen in the ITO waste target, and the intermediate of In2S3and In4SnS8can be produced, which avoids the generation of indium oxide. For example, in some embodiments, the sulfidation reaction temperature can be in the range of 320°C to 410°C, 350°C to 380°C, 360°C to 470°C, or a combination thereof. In some embodiments, the temperature can be raised to 300°C to 430°C at a temperature rise rate of 8°C / min to 12°C / min. For example, the temperature rise rate can be 10°C / min.

[0030] In some embodiments, the sulfidation reaction time can be in the range of 3h to 5h. At the above sulfidation reaction time, the indium and tin elements in the ITO waste target can be completely sulfidized. For example, the sulfidation reaction time can be 4h.

[0031] In some embodiments, in some embodiments, since the sulfidation process of the ITO waste target with sulfur can have some sulfur not fully reacted, a process to remove the unreacted sulfur after the sulfidation process can be needed. The process to remove the sulfur can include: after the sulfidation reaction is completed, heating to 780°C to 820°C to make the sulfur into a gas and then volatilize to remove the unreacted sulfur under an inert atmosphere. For example, the heating can be at 790°C to 810°C, 795°C to 800°C, or a combination of the above temperature ranges. In some embodiments, the process to remove the sulfur can include: after the sulfidation reaction is completed, heating to 580°C to 620°C at a heating rate of 4°C / min to 6°C / min to volatilize the residual unreacted sulfur, and then heating to 780°C to 820°C at a heating rate of 4°C / min to 6°C / min, and holding for 0.5 h to 1.5 h to make the sulfur more fully volatilize. For example, after the sulfidation reaction is completed, heating to 600°C at a heating rate of 5°C / min to volatilize the residual unreacted sulfur, and then heating to 800°C at a heating rate of 6°C / min, and holding for 1 h to make the sulfur more fully volatilize.

[0032] In some embodiments, for step 03, the intermediate can be heated to 1100°C to 1200°C under a vacuum environment of 8 Pa to 12 Pa, and after the reaction is completed, a mixed gas containing indium sulfide and tin sulfide is obtained. At a pressure of 8 Pa to 12 Pa and a temperature of 1100°C to 1200°C, the intermediate can be decomposed into indium sulfide and tin sulfide, and the indium sulfide and tin sulfide are in a gaseous state at this temperature range. In some embodiments, the temperature at which the intermediate is heated can be 1120°C to 1180°C, 1140°C to 1160°C, 1148°C to 1152°C, or a combination of the above ranges. In some embodiments, the holding time after heating to 1100°C to 1200°C can be 1.5 h to 2.5 h. At the above holding time, the intermediate can be fully decomposed into indium sulfide and tin sulfide, and the indium sulfide and tin sulfide can be fully changed into a gaseous state. For example, the holding time can be 1.6 h to 2.4 h, 1.7 h to 2.2 h, 1.8 h to 2.0 h, or a combination of the above ranges. In some embodiments, the temperature can be increased to 1100°C to 1200°C at a heating rate of 4°C / min to 6°C / min. For example, the heating rate can be 5°C / min.

[0033] In some embodiments, for step 04, the mixed gas containing In2S3and SnS can be reacted at a temperature of 800-850°C under a vacuum environment of 8-12 Pa, and after the reaction, condensed In2S3and a gas containing SnS are obtained. At a pressure of 8-12 Pa and a temperature of 800-850°C, In2S3can be condensed, while SnS and possibly remaining S can be avoided from condensing, thereby realizing the condensation and recovery of In2S3. For example, the pressure can be set to 9-11 Pa, and the temperature can be set to 810-840°C. For another example, the pressure can be set to 10 Pa, and the temperature can be set to 825°C. In some embodiments, the mixed gas containing In2S3and SnS can be kept at a temperature of 800-850°C for 1.5-2.5 h. At the above holding time, the maximum possible condensation of In2S3can be ensured. For example, the holding time can be 1.6-2.3 h, 1.8-2.2 h, 1.9-2.0 h, or a combination thereof.

[0034] In some embodiments, for step 05, the gas containing SnS can be reacted at a temperature of 550-650°C under a vacuum environment of 8-12 Pa, and after the reaction, condensed SnS is obtained. At a pressure of 8-12 Pa and a temperature of 550-650°C, SnS can be condensed and recovered, while remaining S can be avoided from condensing. For example, the pressure can be set to 9-11 Pa, and the temperature can be set to 570-630°C. For another example, the pressure can be set to 10 Pa, and the temperature can be set to 600°C. In some embodiments, the gas containing SnS can be kept at a temperature of 550-650°C for 1.5-2.5 h. At the above holding time, the maximum possible condensation of SnS can be ensured. For example, the holding time can be 1.6-2.3 h, 1.8-2.2 h, 1.9-2.0 h, or a combination thereof.

[0035] In some embodiments, the intermediate is an In2S3 / In4SnS8 composite material composed of In2S3and In4SnS8and having a heterojunction structure.

[0036] In some embodiments, the intermediate can have In2S3lattice fringes and In4SnS8lattice fringes. The (210) lattice fringe spacing of In2S3is 0.342 nm, and the (103) lattice fringe spacing of In4SnS8is 0.626 nm.

[0037] In some embodiments, after the reaction of the tin sulfide-containing gas at a temperature of 550-650°C is completed, the system pressure can be maintained at 20 Pa or more to obtain condensed tin sulfide. Maintaining the pressure at 20 Pa or more can avoid loss of indium sulfide and tin sulfide during the cooling process. For example, the system pressure can be maintained at 100 Pa or more, 500 Pa or more, or 1000 Pa or more.

[0038] In some embodiments, the purity of the indium sulfide obtained in step 04 is 4N or more, and the purity of the tin sulfide obtained in step 05 is 2N or more.

[0039] In order to better understand the present application, the following further illustrates the content of the present application with specific examples, but the content of the present application is not limited only to the following examples.

[0040] As Figure 1 The ITO waste target recovery device is shown in FIG. 1. The device includes an argon gas cylinder 1, a flow meter 2, a pressure gauge 3, a quartz tube 4, a graphite boat 5, a heating body 6, a heat insulation material 7, a thermocouple 8, a graphite paper 9, a flange ring 10, a control cabinet 11, a vacuum pump 12, a filter tank 13, a corrugated pipe 14, a cold water tank 15, a gas washing cylinder 16, a safety bottle 17, and a gas washing cylinder 18. The argon gas cylinder 1 is connected to the quartz tube 4 via a gas pipe, and is used to introduce high-purity argon into the quartz tube 4. The flow meter 2 is arranged at the outlet of the argon gas cylinder 1, and is used to monitor the argon flow. The pressure gauge 3 is arranged on the quartz tube 4, and is used to monitor the pressure in the tube. The quartz tube 4 is externally provided with the heating body 6, which is used to heat the quartz tube 4. The heating body 6 is arranged at the front section, the middle section, and the end of the quartz tube 4, and is numbered 1, 2, and 3, respectively. The heating bodies 1, 2, and 3 are controlled by temperature control devices 1, 2, and 3, respectively. The heat insulation material 7 is arranged on the outer surface of the quartz tube 4. The graphite boat 5 is arranged in the quartz tube 4, and is used to hold raw materials. The quartz tube 4 is provided with the thermocouples 8 at both ends and in the middle, which are used to monitor the temperature in different regions. The graphite paper 9 is arranged on the inner wall of the quartz tube 4, and is used to collect condensed indium oxide and tin oxide. The quartz tube 4 is provided with the flange rings 10 at both ends. The inlet of the safety bottle 17 is connected to the outlet of the quartz tube 4, and the outlet of the safety bottle 17 is connected to the inlet of the gas washing cylinder 18. The safety bottle 17 is used to prevent back suction. The gas washing cylinder 18 contains sodium hydroxide. The gas washing cylinder 16 is placed in the cold water tank 15, and the inlet thereof is connected to the outlet of the quartz tube 4. The outlet of the gas washing cylinder 16 is connected to one end of the filter tank 13 via the corrugated pipe 14, and the other end of the filter tank 13 is connected to the vacuum pump 12. The control cabinet 11 is used to control the temperature in the quartz tube 4.

[0041] The following examples all use the ITO waste target recovery device shown in FIG. 1. Figure 1 The ITO waste target recovery device shown in FIG. 1 is used to recover ITO waste targets.

[0042] Example 1

[0043] A method for recycling ITO waste targets may include the following steps:

[0044] Step 1: Weigh 50 g of ITO waste target powder, 50 g of sublimed sulfur powder and 4.5 g of graphite powder, mix them and place them in a graphite boat.

[0045] Step 2: Stir and mix the mixture obtained in step 1 evenly, add 1 / 4 of the total mass of anhydrous ethanol as a pore-forming agent during the stirring process, and then place the mixture in a forced air drying oven and dry it at 90°C for 40 minutes. As the anhydrous ethanol vaporizes, a large number of voids can be formed on the surface and inside of the mixture to obtain a porous material.

[0046] Step 3: Push the graphite boat filled with the pore-forming material into the quartz tube covered with graphite paper, and place the graphite boat at the center of the No. 1 heating element (such as Figure 1 As shown), connect the flange ring and connect the quartz tube to the argon cylinder, vacuum pump, safety bottle, etc. through the gas pipe.

[0047] In step 4, to prevent oxidation of indium and tin, perform a purge step. Close the valves on the safety bottle, purge bottle, and argon bottle, open the vacuum pump valve, and then pump the vacuum pump to 6 Pa. Then, open the argon bottle valve and introduce inert gas for 10 minutes to keep the system oxygen-free and dry, allowing the pressure in the system to return to near-normal pressure.

[0048] Step 5: Close the vacuum pump valve and the argon bottle valve, open the safety bottle valve, and open the purge bottle valve. Turn on temperature control devices 1, 2, and 3, and control the first temperature section to increase the temperature to 400°C at a rate of 8°C / min. Maintain the temperature for 3 hours to carry out the vulcanization reaction.

[0049] Step 6, adjust the temperature control devices No. 2 and No. 3 to control the heating elements No. 2 and No. 3 to heat up to 500°C at a heating rate of 4°C / min, and start heat preservation to avoid condensation of sulfur in the quartz tube. Adjust the temperature control device No. 1 to control the heating element No. 1. After the sulfurization reaction is completed, heat up to 600°C at a heating rate of 4°C / min to volatilize the residual unreacted sulfur. When the temperature reaches above 600°C, turn on the vacuum pump, close the valve of the gas washing bottle, and control the argon flow rate by controlling the closure of the argon bottle valve so that the pressure in the system is not less than 5Pa (to avoid rapid and large-scale volatilization of sulfur due to too low pressure, which causes gaseous sulfur to condense in the rubber tube and cause blockage), and continue to heat up to 800°C.

[0050] Step 7: Close the argon cylinder valve and adjust the No. 1 temperature control device to control the No. 1 heating element to maintain the temperature at 800° C. for 0.5 h to ensure sufficient volatilization of the sulfur element to obtain the intermediate.

[0051] Step 8, open the argon cylinder valve, control the pressure in the system at 8Pa, adjust the No. 1 temperature control device to control the No. 1 heating element to continue to heat up to 1100°C at a heating rate of 4°C / min, keep warm for 2 hours, so that indium sulfide, tin sulfide, etc. volatilize into the No. 2 heating element. Adjust the No. 2 temperature control device to control the No. 2 heating element, heat it up to 800°C at a heating rate of 4°C / min, keep warm for 2 hours, so as to condense the indium sulfide and avoid condensation of tin sulfide and residual sulfur. Adjust the No. 3 temperature control device to control the No. 3 heating element, heat it up to 550°C at a heating rate of 4°C / min, keep warm for 2 hours, so as to condense the tin sulfide and avoid condensation of residual sulfur.

[0052] Step 9: After the insulation is completed, argon gas is continuously introduced to maintain the pressure at 25 Pa to avoid volatilization loss of indium sulfide and tin sulfide during the cooling process, and the device is cooled to room temperature.

[0053] Step 10, after the device is cooled to room temperature, the graphite paper is taken out, and the experimental products condensed in different temperature zones are obtained at different positions on the graphite paper. 4N indium sulfide is obtained at heating element No. 2, and 2N tin sulfide is obtained at heating element No. 3.

[0054] The TEM image of the intermediate obtained in this example is as follows Figure 2 As shown. Figure 2 It can be found that In2S3 / In4SnS8 heterojunctions are formed during the sulfurization process of the ITO waste target. After the sulfurization reaction, fungus-shaped In2S3 / In4SnS8 nanosheets appear on the surface of the ITO waste target. In high-resolution TEM observations show that the (210) lattice fringes of In2S3 (such as Figure 2 (A) in the figure), the spacing is 0.342nm, and the (103) lattice fringes of In4SnS8 (such as Figure 2 In (B), the spacing is 0.626 nm, indicating a heterojunction. Furthermore, the Sn, In, and S elements are evenly distributed in the composite material.

[0055] Example 2

[0056] A method for recycling ITO waste targets may include the following steps:

[0057] Step 1: weigh 50 g of ITO waste target powder, 70 g of sublimated sulfur powder and 4 g of graphite powder, stir and mix them evenly to obtain a mixture.

[0058] Step 2: Stir and mix the mixture obtained in step 1 evenly, add 1 / 4 of the total mass of anhydrous ethanol as a pore-forming agent during the stirring process, and then place the mixture in a blast drying oven and dry it at 90°C for 40 minutes. As the anhydrous ethanol vaporizes, a large number of voids can be created on the surface and inside of the mixed material to obtain a porous material.

[0059] Step 3, push the graphite boat containing the material after the pore forming into the quartz tube covered with graphite paper inside, place the graphite boat at the center of the first heating element (as shown in Figure 1 Figure), connect the flange ring, and connect the quartz tube with the argon cylinder, vacuum pump, safety bottle, etc. through the gas pipe.

[0060] Step 4, to prevent the oxidation of indium and tin, first perform the gas washing step. Close the safety bottle valve, gas washing bottle valve, and argon cylinder valve, open the vacuum pump valve, then start the vacuum pump to reduce the pressure to 12 Pa, then open the argon cylinder valve, introduce inert gas for 10 min, and keep the system in an oxygen-free and dry state, so that the pressure in the system returns to near atmospheric pressure.

[0061] Step 5, close the vacuum pump valve and argon cylinder valve, open the safety bottle valve and gas washing bottle valve. Start the temperature control devices 1, 2, and 3, control the first temperature section to heat up to 400℃ at a rate of 12℃ / min, and keep the temperature for 3h for vulcanization reaction.

[0062] Step 6, adjust the temperature control devices 2 and 3 to control the second and third heating elements to heat up to 500℃ at a rate of 6℃ / min, start the temperature holding to avoid the condensation of elemental sulfur in the quartz tube. After the temperature holding of the first heating element at 400℃ is completed, adjust the temperature control device 1 to control the first heating element to heat up to 600℃ at a rate of 6℃ / min to volatilize the residual unreacted sulfur. When the temperature reaches above 600℃, start the vacuum pump, close the gas washing bottle valve, and control the argon flow rate by closing the argon cylinder valve to control the pressure in the system not to be lower than 5 Pa (to avoid the rapid volatilization of sulfur due to low pressure, which may cause the condensation of gaseous sulfur in the rubber tube and cause blockage), and continue to heat up to 800℃.

[0063] Step 7, close the argon cylinder valve, adjust the temperature control device 1 to control the first heating element to keep the temperature at 800℃ for 0.5h to ensure the sufficient volatilization of elemental sulfur.

[0064] Step 8, open the argon cylinder valve, control the pressure in the system to be 12 Pa, adjust the temperature control device 1 to control the first heating element to continue to heat up to 1200℃ at a rate of 6℃ / min, and keep the temperature for 2h to make indium sulfide and tin sulfide volatilize into the second heating element position. Adjust the temperature control device 2 to control the second heating element to heat up to 850℃ at a rate of 6℃ / min, and keep the temperature for 2h to condense indium sulfide and avoid the condensation of tin sulfide and residual elemental sulfur. Adjust the temperature control device 3 to control the third heating element to heat up to 650℃ at a rate of 6℃ / min, and keep the temperature for 2h to condense tin sulfide and avoid the condensation of residual elemental sulfur.

[0065] Step 9, after the end of the incubation, continue to pass argon, keep the pressure at 30 Pa, avoid the volatilization loss of indium sulfide and tin sulfide in the cooling process, and wait until the device cools to room temperature.

[0066] Step 10, after the device cools to room temperature, remove the graphite paper, and get the experimental products condensed at different temperature zones at different positions on the graphite paper, get 4N indium sulfide at No. 2 heating body, and get 2N tin sulfide at No. 3 heating body.

[0067] Although the present application has been described above by incorporating the exemplary embodiments, it should be apparent that various modifications and changes to the exemplary embodiments can be made without departing from the spirit and scope of the application as defined in the following claims.

Claims

1. A method for recycling ITO waste targets, characterized in that: The following steps are involved: mixing a waste ITO target, sulfur and graphite to obtain a mixture; The mixture is placed in an inert environment and heated to 300°C to 430°C for a sulfurization reaction, and an intermediate is obtained after the reaction is completed; The intermediate is heated to 1100° C. to 1200° C. under a first pressure, and a mixed gas containing indium sulfide and tin sulfide is obtained after the reaction is completed; Under a second pressure, the mixed gas containing indium sulfide and tin sulfide is placed at a temperature of 800° C. to 850° C., and after the reaction is completed, condensed indium sulfide and tin sulfide-containing gas are obtained respectively; Under the third pressure, the gas containing tin sulfide is placed at a temperature of 550° C. to 650° C., and condensed tin sulfide is obtained after the reaction is completed.

2. The ITO waste target recovery method according to claim 1, wherein: The first pressure, the second pressure and the third pressure are 8Pa to 12Pa.

3. The ITO waste target recovery method according to claim 1 or 2, characterized in that: The intermediate is heated to 1100° C. to 1200° C. and then kept at this temperature for 1.5 to 2.5 hours until the reaction is completed, thereby obtaining a mixed gas containing indium sulfide and tin sulfide.

4. The ITO waste target recovery method according to claim 1 or 2, characterized in that: The mixed gas containing indium sulfide and tin sulfide is placed at a temperature of 800° C. to 850° C. and kept warm for 1.5 hours to 2.5 hours until the reaction is completed, thereby obtaining condensed indium sulfide and gas containing tin sulfide.

5. The ITO waste target recovery method according to claim 1 or 2, characterized in that: The gas containing tin sulfide is placed at a temperature of 550° C. to 650° C. and kept warm for 1.5 hours to 2.5 hours until the reaction is completed to obtain condensed tin sulfide.

6. The ITO waste target recovery method according to claim 1 or 2, characterized in that: The intermediate is an In2S3 / In4SnS8 composite material composed of In2S3 and In4SnS8 and having a heterojunction structure.

7. The ITO waste target recovery method according to claim 1, 2 or 6, characterized in that: The gas containing tin sulfide is placed at a temperature of 550° C. to 650° C. until the reaction is completed, and the system pressure is maintained above 20 Pa to obtain condensed tin sulfide.

8. The ITO waste target recovery method according to claim 1, 2 or 6, characterized in that: The method also includes raising the temperature to 780° C. to 820° C. and maintaining the temperature for 0.5 h to 1.5 h after the sulfurization reaction is completed to remove unreacted sulfur, and obtaining an intermediate after the reaction is completed.

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