Method for recovering residual ito target and ito target material

Abstract

The application belongs to the technical field of metal recovery, and discloses a method for recycling ITO residual targets, comprising the following steps: mixing ITO particles with tin liquid to obtain a mixture; gasifying the mixture in a crucible to obtain a mixed gas; collecting, cooling, crystallizing, and sieving the mixed gas to obtain ITO powder; and adding tin liquid to make tin into tin oxide in an oxygen environment, thereby increasing the content of tin oxide in the mixed gas, avoiding the loss caused by the fact that tin oxide is condensed first when the gas is collected, and achieving the purpose of supplementing tin oxide; moreover, the tin liquid and the ITO residual target particles are fully mixed, the flowability of the particles can be improved, the voltage can be kept stable during the gasification process, the rapid arc rising temperature can make the powder better gasify, the height of the air extraction hood is adjusted to collect the gas, and the uniformity of the powder is improved; in addition, the application also discloses an ITO target material prepared from the ITO powder prepared by the above method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal recovery, and particularly relates to an ITO residual target recovery method and ITO target material. BACKGROUND

[0002] ITO (indium tin oxide) target material is an oxide ceramic material with a weight ratio of indium oxide to tin oxide of 90:10. It is widely used in screen displays, photovoltaic cells and functional glass due to its high transparency, good electrical conductivity, excellent thermal stability and mechanical properties. However, a certain amount of residual targets are often produced during the production and use of ITO target material. These residual targets contain indium and tin that have not been consumed and have certain economic value. After reasonable recovery and treatment, the waste of resources and environmental pollution can be effectively reduced. Therefore, the recovery of ITO residual targets has become an important research field in the current material utilization and sustainable development. At present, the recovery technologies of ITO residual targets mainly include mechanical method, chemical method and heat treatment method. The mechanical method mainly processes the residual targets through physical methods such as crushing and grinding to separate useful components. The chemical method usually extracts indium and tin from the residual targets by means of solvent leaching. The heat treatment method uses high-temperature chemical reaction to decompose the material and then extracts the required metal.

[0003] Among them, Chinese patent application 201510663551.0 discloses a method for efficiently recovering ITO waste targets. The method is as follows: first, the surface of the ITO waste target is ultrasonically cleaned with an organic solvent, and then ultrasonically cleaned with pure water; then the cleaned ITO waste target is used as an anode, and a graphite rod is used as a cathode for primary gasification. After condensation, ITO powder with a specific surface area less than 5m 2 / g is recovered from coarse ITO powder by a grading screening device, and ITO powder with a specific surface area less than 5m 2 / g is subjected to secondary gasification, and ITO powder with a specific surface area of 5-10m 2 / g is recovered by condensation.

[0004] However, in this scheme, ITO waste targets exist in the form of particles, and the flowability between particles is poor, which can cause unstable electric arc of the electrode and easily cause arc breaking phenomenon, affecting the uniformity of the obtained powder particle size.

[0005] The problem to be solved by the present application is: how to provide an ITO residual target recovery method. SUMMARY

[0006] The purpose of the present application is to provide an ITO residual target recovery method, which fully mixes ITO residual target particles with a tin liquid and a tin oxide in a mass ratio of 90:10, improves the fluidity of the particles, thereby maintaining a stable voltage during the gasification process, quickly arcing and heating to enable better gasification of the powder, and adjusting the height of the air extraction hood to improve the uniformity of the powder.

[0007] To achieve the above-mentioned purpose, the present application discloses an ITO residual target recovery method, which comprises the following steps:

[0008] Step 1: mixing ITO particles with a tin liquid to obtain a mixture;

[0009] Step 2: placing the mixture into a crucible and heating it in an oxygen environment to gasify the mixture and obtain a mixed gas;

[0010] Step 3: collecting, cooling, crystallizing, homogenizing and sieving the mixed gas to obtain ITO powder;

[0011] In step 1, the mass ratio of ITO particles to tin liquid is 90-99:10-1;

[0012] The crucible is fixed with an air extraction hood at a distance of 5-20 cm from the surface of the mixture inside the crucible;

[0013] During the gas condensation of ITO particles, the melting point of tin oxide is lower than that of indium oxide, so part of the tin oxide will crystallize first during the collection process, resulting in the mass content of tin oxide in the obtained ITO powder being less than 10wt%. By adding a tin liquid and making tin into tin oxide in an oxygen environment, the content of tin oxide in the ITO gas is increased, thereby avoiding the loss of tin oxide and achieving the purpose of supplementing tin oxide;

[0014] On the one hand, the use of tin liquid can help ITO particles have good fluidity, thereby making the electric arc more stable during the gasification process, quickly heating the powder to enable gasification, which is beneficial to improving the uniformity of ITO powder. In addition, the air extraction hood can quickly cool the high-temperature gasified powder, and by adjusting the height of the air extraction hood, the cooling rate of the gasified gas can be adjusted to obtain ITO powder with smaller particle size and higher uniformity, thereby facilitating the subsequent grinding process of the target material and making the sintered ITO target material have better density.

[0015] Preferably, the crucible in step 2 is arranged in a plasma arc magnetic rotating gasification powder production furnace, and the plasma arc magnetic rotating gasification powder production furnace further comprises an electrode, a graphite electrode, a direct current voltage output device and a magnetic coil.

[0016] One end of the electrode is connected to the bottom of the crucible, and the other end is connected to the direct current voltage output device.

[0017] The graphite electrode is connected with the direct current voltage output device at one end and is placed in the center of the air extraction hood and extends into the crucible.

[0018] Preferably, the magnetic coil is connected with the direct current voltage output device and forms a series or parallel connection with the electrode and the graphite electrode.

[0019] Preferably, the voltage of the direct current voltage output device is 20-70V.

[0020] Preferably, the ITO particles in step 1 are obtained by crushing the ITO residual target, soaking in an organic solvent and drying;

[0021] and the tin liquid is obtained by melting tin ingots with a purity of 99.99% at 400-600℃.

[0022] Preferably, the organic solvent is at least one selected from isopropyl alcohol, propanol and ethanol.

[0023] Preferably, the temperature during vaporization in step 2 is not lower than 4000℃.

[0024] In addition, an ITO target material is also disclosed, which is prepared from the ITO powder obtained by the ITO residual target recycling method described above.

[0025] The present application has the following advantages:

[0026] The present application provides an ITO residual target recycling method, by adding tin liquid, tin becomes tin oxide in the presence of oxygen, thereby increasing the content of tin oxide in the mixed gas, so as to avoid the loss caused by the condensation of tin oxide during the collection of the gas, and achieve the purpose of supplementing tin oxide; and the ITO particles also have good fluidity, so that the electric arc in the vaporization process is more stable, the powder is rapidly heated to vaporize, which is beneficial to improve the uniformity of the ITO powder, and the powder vaporized at high temperature can be rapidly cooled by the air extraction hood, and by adjusting the height of the air extraction hood, the cooling rate of the gas after vaporization can be adjusted, and the particle size uniformity of the prepared ITO powder is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Figure 1 is a schematic diagram of an ITO residual target particle recycling device, wherein 1 is a plasma arc magnetic rotating gasification powder preparation furnace, 2 is an ITO residual target particle, 3 is a tin liquid, 4 is an air extraction hood, 5 is a graphite electrode, 6 is a cyclone separator, 7 is a cyclone collection bin, 8 is a bag dust collector, and 9 is a bag collection bin. DETAILED DESCRIPTION

[0028] In the description of the present application, it should be noted that, in the examples, the specific conditions are not specified, and the conventional conditions or manufacturer's recommended conditions are used. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0029] In the following examples and comparative examples, the plasma arc magnetic force rotating gasification powder making furnace is the plasma arc magnetic force rotating gasification powder making furnace described in the prior patent 202010414972.0.

[0030] Example 1

[0031] Reference Figure 1 , the ITO residual target recovery method is specifically:

[0032] Step 1: crush the ITO residual target with a mass ratio of indium oxide to tin oxide of 90:10, soak in an organic solvent for 3h, dry, and obtain ITO particles 2; mix the obtained ITO particles 2 with tin ingots with a purity of 99.99% at 500℃ to obtain a tin liquid 3, and mix the tin liquid 3 with a mass ratio of 95:5 to obtain a mixture;

[0033] Step 2: place the mixture into the crucible of the plasma arc magnetic force rotating gasification powder making furnace 1, and wrap the outer wall of the crucible with a magnetic coil and an electrode and a graphite electrode 5 to form a series circuit, so that the mixture is gasified in an oxygen environment, and the gasification temperature is 4500℃, to obtain a mixed gas;

[0034] Wherein, one end of the electrode in the plasma arc magnetic force rotating gasification powder making furnace 1 is connected with the bottom of the crucible, and the other end is connected with the direct current voltage output device;

[0035] One end of the graphite electrode 5 is connected with the direct current voltage output device, and the other end is placed at the center position of the exhaust hood 4 and extends into the interior of the crucible;

[0036] The distance between the exhaust hood 4 and the surface of the mixture in the crucible is 12cm;

[0037] The output voltage of the direct current voltage output device is 35V;

[0038] Step 3: pass the mixed gas through a cyclone separator 6 to make part of the condensed tin oxide powder formed into a cyclone collection bin 7, and the remaining gas into a bag dust collector 8 to cool and crystallize, and then sieve through an 80 mesh screen, to obtain ITO powder in a bag collection bin 9.

[0039] Example 2

[0040] The same as example 1, the difference is that the distance between the exhaust hood and the surface of the mixture in the crucible is 5cm.

[0041] Example 3

[0042] The same as example 1, except that the distance between the hood and the surface of the mixture in the crucible is 20 cm.

[0043] Example 4

[0044] The same as example 1, except that the mass ratio of ITO particles to tin liquid in step 1 is 90:10.

[0045] Example 5

[0046] The same as example 1, except that the mass ratio of ITO particles to tin liquid in step 1 is 99:1.

[0047] Comparative example 1

[0048] The same as example 1, except that tin powder is used instead of tin liquid in step 1.

[0049] Comparative example 2

[0050] The same as example 1, except that indium liquid is used instead of tin liquid in step 1.

[0051] Comparative example 3

[0052] The same as example 1, except that the mass ratio of ITO particles to tin liquid in step 1 is 88:12.

[0053] Comparative example 4

[0054] The same as example 1, except that the mass ratio of ITO particles to tin liquid in step 1 is 99.5:0.5.

[0055] Comparative example 5

[0056] The same as example 1, except that the distance between the hood and the surface of the mixture in the crucible is 3 cm.

[0057] Comparative example 6

[0058] The same as example 1, except that the distance between the hood and the surface of the mixture in the crucible is 30 cm.

[0059] Performance test:

[0060] Difference = ITO powder D90 particle size - ITO powder D50 particle size.

[0061] The ratio of indium oxide to tin oxide in the ITO powder: the composition of the ITO powder is detected using an XRF spectrometer;

[0062] The test results are shown in Table 1:

[0063] Table 1

[0064]

[0065]

[0066] Conclusion analysis:

[0067] 1. From the data of Example 1-3 combined with Table 1, it can be seen that when the mass ratio of ITO particles to tin liquid is the same, the ratio of indium oxide to tin oxide in the ITO powder obtained by changing the distance between the exhaust hood and the surface of the mixture in the crucible is all close to 90:10.

[0068] And further observation shows that the ITO powder in Example 1 has a smaller particle size, and the difference between the D50 particle size and the D90 particle size is also the smallest, while the particle size of the ITO powder in Example 2 and Example 3 and the difference between the D50 particle size and the D90 particle size are larger than that of Example 1. Therefore, the process parameters of Example 1 are the best parameters.

[0069] 2. From Example 1, Example 4-5, it can be seen that compared with Example 1, when we change the ratio of ITO particles to tin liquid, the ratio of indium oxide to tin oxide in the ITO powder prepared will also be further away from the ratio of indium oxide to tin oxide = 90:10, and the particle size of the ITO powder will be larger than that of Example 1, causing the difference between the D50 particle size and the D90 particle size of the ITO powder to increase, thereby affecting the uniformity of the ITO powder. Therefore, the mass ratio of ITO particles to tin liquid in Example 1 is the best ratio.

[0070] 3. From Example 1 and Comparative Example 1, when tin powder is used to replace tin liquid, although the ratio of indium oxide to tin oxide in the ITO powder prepared is close, because the powder cannot flow freely like the liquid, the addition of tin powder cannot achieve the effect of stabilizing the arc, thereby causing the particle size of the ITO powder to increase, and the difference between the D50 particle size and the D90 particle size of the ITO powder also increases to 3.77 μm.

[0071] Further observation of Comparative Example 2 shows that when indium liquid, which is also a liquid, is used instead of tin liquid, the indium liquid can also stabilize the arc, thereby facilitating the vaporization of ITO particles, and the specific surface area of the ITO target material prepared from the ITO powder is also not much different, but the ITO powder prepared has a problem of excessive indium content. Therefore, it can be seen that tin liquid cannot be replaced.

[0072] 4. From Example 1, Comparative Examples 3-4, it can be seen that when the mass ratio of tin liquid in the mixture is too small, a small amount of tin liquid cannot stabilize the electric arc, thereby affecting the vaporization of ITO particles; when the mass ratio of tin liquid in the mixture is too large, too much tin liquid will vaporize with the heating of the electric arc, thereby causing the SnO2 content in the powder obtained after gas cooling to be too high, and the SnO2 content in the ITO powder being too high will affect the performance of the target material prepared.

[0073] 5. From Example 1, Comparative Examples 5-6, it can be seen that when the distance between the exhaust hood and the surface of the mixture is reduced, the gas after vaporization will be extracted by the exhaust hood too early, thereby causing the gas to crystallize too early, the crystal growth structure to be uneven, and the particle size of the ITO powder to be affected;

[0074] When the distance between the exhaust hood and the surface of the mixture is increased, part of the gas has already nucleated during the rising process, causing the particle size of the ITO powder after crystallization to be large, and causing the difference between the D50 particle size and the D90 particle size to be large, reaching 3.68 μm, thereby affecting the uniformity of the ITO powder.

[0075] The above examples are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. A method for recovering ITO residual targets, characterized in that: The following steps are involved: Step 1: Mixing ITO particles with tin liquid to obtain a mixture; Step 2: placing the mixture into a crucible and heating it in an oxygen environment to vaporize the mixture to obtain a mixed gas; Step 3: Collect, cool, crystallize and sieve the mixed gas to obtain ITO powder; Wherein, in step 1, the mass ratio of ITO particles to tin liquid is 90-99:10-1; The crucible is fixed with an exhaust hood which is 5 to 20 cm away from the surface of the mixture inside the crucible.

2. The method according to claim 1, characterized in that In step 2, the crucible is placed in a plasma arc magnetic rotary gasification powder making furnace, and the plasma arc magnetic rotary gasification powder making furnace further includes an electrode, a graphite electrode, a DC voltage output device, and a magnetic coil; One end of the electrode is connected to the bottom of the crucible, and the other end is connected to the DC voltage output device; One end of the graphite electrode is connected to the DC voltage output device, and the other end is placed at the center of the exhaust hood and extends into the crucible.

3. The method according to claim 2, characterized in that The magnetic coil is connected to a DC voltage output device and is connected in series or in parallel with the electrode and the graphite electrode.

4. The method according to claim 2, characterized in that The voltage of the DC voltage output device is 20-70V.

5. The method according to claim 1, wherein In step 1, the ITO particles are obtained by crushing the ITO target residue, soaking it in an organic solvent, and drying it; The tin liquid is obtained by melting a tin ingot with a purity of ≥99.99% at 400-600°C.

6. The method according to claim 5, characterized in that The organic solvent is selected from at least one of isopropyl alcohol, propanol and ethanol.

7. The method according to claim 1, characterized in that The temperature during gasification in step 2 is not less than 4000°C.

8. An ITO target, characterized in that: The invention is made from the ITO powder obtained by the ITO target remnant recovery method described in any one of claims 1 to 7.

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