Method for recovering indium fluoride and tin oxide from ITO waste target

Abstract

The invention provides a method for recycling indium fluoride and tin oxide from an ITO waste target, and belongs to the technical field of waste indium tin oxide target recycling. The method comprises the steps that hydrofluoric acid is adopted for acid leaching of powder of the ITO waste target, acid leaching slurry is obtained, and the acid leaching slurry contains indium fluoride and tin oxide; carrying out vacuum distillation on the acid leaching slurry to respectively obtain indium fluoride-containing gas and tin oxide solid; the temperature of the vacuum distillation is 1000 to 1100 DEG C; the vacuum degree of the vacuum distillation is 5-20 Pa; carrying out vacuum condensation on the indium fluoride gas to obtain an indium fluoride solid; the condensation temperature is 700 to 800 DEG C; the purity of the tin oxide solid is gt; the content is 99.999%; the purity of indium fluoride obtained through vacuum condensation is gt; the yield is 99.99%. The method provided by the invention has the advantages of low energy consumption, no carbon emission, low cost and high added value, and can realize conversion and recovery of waste materials into high-value materials.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling waste indium tin oxide targets, and in particular relates to a method for recycling indium fluoride and tin oxide from waste ITO targets. Background Art

[0002] Indium tin oxide (ITO) target refers to a compound target composed of three elements: tin, indium, and oxygen. It usually contains about 90% indium oxide and 10% tin oxide. Because of its excellent conductivity, transparency and chemical stability, it is widely used in display devices such as LCD, PDP, OLED, etc. With the replacement of mobile devices such as smart phones and tablets, and the rapid rise of emerging fields such as smart homes and smart travel, the demand and waste of ITO targets are also increasing. Indium used in the preparation of ITO targets accounts for more than 80% of the total indium consumption each year, and it is the most important raw material for the secondary resource recovery of rare metal indium.

[0003] At present, the main methods for recycling ITO waste targets are vacuum reduction and wet-electrolysis. The vacuum reduction method includes carbon thermal reduction and hydrogen reduction. Generally, the carbon thermal reduction temperature reaches 1200-1700℃, with high energy consumption and high requirements for equipment. The production of carbon dioxide does not meet the prospects of carbon emission reduction in my country. The hydrogen reduction method has the problem of high cost. The crude indium (2N) recovered by the wet-electrolysis method does not meet industrial requirements. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for recovering indium fluoride and tin oxide from ITO waste targets. The method provided by the present invention has low energy consumption, no carbon emissions, low cost, and the recovered indium fluoride and tin oxide have high purity.

[0005] In order to achieve the above object, the present invention provides the following scheme:

[0006] The present invention provides a method for recovering indium fluoride and tin oxide from ITO waste targets, comprising the following steps:

[0007] Using hydrofluoric acid to acid-leach the powder of the ITO waste target to obtain an acid-leach slurry, wherein the acid-leach slurry contains indium fluoride and tin oxide;

[0008] The acid leaching slurry is subjected to vacuum distillation to obtain indium fluoride-containing gas and tin oxide solid respectively; the temperature of the vacuum distillation is 1000-1100° C.; the vacuum degree of the vacuum distillation is 5-20 Pa;

[0009] The indium fluoride gas is subjected to vacuum condensation to obtain indium fluoride solid; the condensation temperature is 700-800° C.;

[0010] The purity of the tin oxide solid is greater than 99.999%; the purity of the indium fluoride obtained by vacuum condensation is greater than 99.99%.

[0011] Preferably, the mass concentration of the hydrofluoric acid is 40-50%.

[0012] Preferably, the mass ratio of the powder of the ITO waste target to the volume ratio of hydrofluoric acid is 1 g: (10-15) mL.

[0013] Preferably, the acid leaching temperature is 65-75° C. and the time is 1.5-2.5 h.

[0014] Preferably, the powder of the ITO waste target has a mesh size of 100 to 200 meshes.

[0015] Preferably, the composition of the ITO waste target is In2O3 89.4%, SnO2 9.9%, Ca 0.6%, and Mg 0.1%.

[0016] Preferably, the insulation time of the vacuum distillation is 1 to 2 hours.

[0017] Preferably, the insulation time of the vacuum condensation is 1 to 2 hours.

[0018] Preferably, the vacuum degree of the vacuum condensation is 5-20Pa.

[0019] Preferably, the heating rate to the vacuum distillation temperature is 10°C / min.

[0020] The invention provides a method for recovering indium fluoride and tin oxide from an ITO waste target. The method comprises the following steps: acid leaching the powder of the ITO waste target with hydrofluoric acid to obtain an acid leaching slurry, wherein the acid leaching slurry contains indium fluoride and tin oxide; vacuum distilling the acid leaching slurry to obtain indium fluoride-containing gas and tin oxide solid respectively; the temperature of the vacuum distillation is 1000-1100 DEG C; the vacuum degree of the vacuum distillation is 5-20 Pa; vacuum condensing the indium fluoride gas to obtain indium fluoride; the condensation temperature is 700-800 DEG C; the purity of the tin oxide solid is greater than 99.999%; the purity of the indium fluoride obtained by the vacuum condensation is greater than 99.999%. The method provided by the present invention can simultaneously realize the separation and purification of indium and tin in ITO waste targets, recover indium in the form of high-purity indium fluoride material, and recover tin in the form of high-purity tin oxide, wherein the purity of tin oxide is greater than 5N (99.999%), and the purity of indium fluoride is greater than 4N (99.99%). The method provided by the present invention has low energy consumption, no carbon emission, low cost, high added value, and can realize the conversion and recovery of waste materials into high-value materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 It is a schematic diagram of an ITO waste target recovery device; wherein, 1- a high-purity argon gas generating device, 2- a quartz tube, 3- a first temperature-controlled tubular vacuum furnace, 4- a second temperature-controlled tubular vacuum furnace, 5- a tail gas absorption device, and 6- a vacuum pump. DETAILED DESCRIPTION

[0023] The present invention provides a method for recovering indium fluoride and tin oxide from ITO waste targets, comprising the following steps:

[0024] Using hydrofluoric acid to acid-leach the powder of the ITO waste target to obtain an acid-leach slurry, wherein the acid-leach slurry contains indium fluoride and tin oxide;

[0025] The acid leaching slurry is subjected to vacuum distillation to obtain indium fluoride-containing gas and tin oxide solid respectively; the temperature of the vacuum distillation is 1000-1100° C.; the vacuum degree of the vacuum distillation is 5-20 Pa;

[0026] The indium fluoride gas is subjected to vacuum condensation to obtain indium fluoride; the condensation temperature is 700-800° C.;

[0027] The purity of the tin oxide solid is greater than 99.999%; the purity of the indium fluoride obtained by vacuum condensation is greater than 99.99%.

[0028] Unless otherwise specified, the materials and equipment used in the present invention are commercially available products.

[0029] The powder of the ITO waste target is acid-leached with hydrofluoric acid to obtain an acid-leaching slurry containing indium fluoride and tin oxide.

[0030] In the present invention, the composition of the ITO waste target is preferably In2O389.4%, SnO29.9%, Ca0.6%, Mg0.1%. In the present invention, the ITO waste target is waste and defective products generated during the ITO preparation process; the powder of the ITO waste target is preferably obtained by mechanically crushing the ITO waste target.

[0031] In the present invention, the mesh size of the powder of the ITO waste target is preferably 100-200 meshes, and in the embodiment of the present invention, it can be 100 meshes, 150 meshes or 200 meshes.

[0032] In the present invention, the mass concentration of the hydrofluoric acid is preferably 40-50%, and in the embodiment of the present invention, it can be 40%, 42%, 45%, 48% or 50%; the volume ratio of the mass of the powder of the ITO waste target to the hydrofluoric acid is preferably 1g: (10-15) mL, and in the embodiment of the present invention, it can be 1g: 10mL, 1g: 12mL or 1g: 15mL. In the present invention, the temperature of the acid leaching is preferably 65-75°C, and in the embodiment of the present invention, it can be 65, 70, 72 or 75°C; the time of the acid leaching is preferably 1.5-2.5h, and in the embodiment of the present invention, it can be 1.5h, 2.0h, 2.2h or 2.5h.

[0033] In the acid leaching process of the present invention, the indium oxide in the ITO waste target reacts with hydrofluoric acid to generate indium fluoride, and the tin oxide does not react. The reaction equation is as follows:

[0034] In2O3+6HF(l)=2InF3+3H2O(g);

[0035] After obtaining the acid leaching slurry, the present invention performs vacuum distillation on the acid leaching slurry to obtain indium fluoride-containing gas and tin oxide solid respectively.

[0036] In the present invention, the vacuum degree of the vacuum distillation is 5-20Pa, and in the embodiment of the present invention, it can be 5Pa, 8Pa, 10Pa, 12Pa, 15Pa or 20Pa. In the present invention, the temperature of the vacuum distillation is 1000-1100℃, and in the embodiment of the present invention, it can be 1000℃, 1030℃, 1050℃, 1060℃, 1080℃, 1090℃ or 1100℃; the insulation time of the vacuum distillation is preferably 1-2h, and in the embodiment of the present invention, it can be 1h, 1.5h or 2h. The present invention preferably heats up from room temperature to the temperature of the vacuum distillation, and the heating rate to the temperature of the vacuum distillation is preferably 10℃ / min.

[0037] In the process of vacuum distillation of the present invention, indium fluoride, water, calcium and magnesium impurities in the acid leaching slurry are completely gasified and separated from tin oxide.

[0038] After obtaining the indium fluoride-containing gas, the present invention performs vacuum condensation on the indium fluoride gas to obtain indium fluoride solid.

[0039] In the present invention, the vacuum degree of the vacuum condensation is preferably 5-20Pa, and in the embodiment of the present invention, it can be 5Pa, 8Pa, 10Pa, 12Pa, 15Pa or 20Pa. In the present invention, the temperature of the vacuum condensation is 700-800℃, and in the embodiment of the present invention, it can be 700℃, 720℃, 740℃, 750℃, 780℃ or 800℃; the insulation time of the vacuum condensation is preferably 1-2h, and in the embodiment of the present invention, it can be 1h, 1.5h or 2h. The present invention preferably heats up from room temperature to the temperature of the vacuum condensation, and the heating rate is preferably 10℃ / min.

[0040] The present invention controls the temperature of vacuum condensation at 700-800° C., can condense indium fluoride, and prevent impurities such as calcium, magnesium and water from cooling, further playing the role of purifying and drying the indium fluoride condensation product.

[0041] In the present invention, the vacuum distillation and vacuum condensation are preferably carried out in a tubular vacuum furnace (respectively referred to as a first temperature-controlled tubular vacuum furnace and a second temperature-controlled tubular vacuum furnace). Figure 1 The figure shows a schematic diagram of the ITO waste target recovery device of the present invention.

[0042] In the present invention, before the vacuum distillation, the first temperature-controlled tubular vacuum furnace and the second temperature-controlled tubular vacuum furnace are preferably cleaned to exhaust the air.

[0043] In the present invention, graphite paper is preferably laid on the inner wall of the quartz tube of the second temperature-controlled tubular vacuum furnace for condensing indium fluoride gas.

[0044] The present invention preferably uses a tail gas absorption device to absorb hydrogen fluoride gas, water and calcium and magnesium impurities during the reaction process (calcium and magnesium impurities may also condense at low temperatures, such as the inner walls of the unheated quartz tubes outside the two temperature-controlled tubular vacuum furnaces).

[0045] In order to further illustrate the present invention, a method for recovering indium fluoride and tin oxide from ITO waste targets provided by the present invention is described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] The ITO waste target is mechanically crushed to 100-200 meshes to obtain powder of the ITO waste target; the composition of the ITO waste target is In2O389.4%, SnO29.9%, Ca 0.6%, and Mg 0.1%;

[0048] The powder of the ITO waste target is put into a polyethylene beaker, and hydrofluoric acid with a mass concentration of 40% is added into the beaker, and the volume ratio of the mass of the powder of the ITO waste target to the hydrofluoric acid is 1g:10mL, and the obtained mixed material is heated to 70°C in a water bath, and acid leaching is performed for 2 hours (the indium oxide in the ITO waste target reacts with the hydrofluoric acid to generate indium fluoride, and the tin oxide does not react), to obtain an acid leaching slurry; the acid leaching slurry contains indium fluoride and tin oxide;

[0049] The acid leaching slurry is poured into a graphite boat, and graphite paper is laid on the inner wall of the quartz tube of the first temperature-controlled tubular vacuum furnace and the second temperature-controlled tubular vacuum furnace for condensing indium fluoride gas;

[0050] The schematic diagram of the ITO waste target recovery device of the present invention is as follows Figure 1 As shown, the temperature control program of the tubular vacuum furnace is set. The first temperature-controlled tubular vacuum furnace: heating starts from room temperature, the heating rate is 10°C / min, the target temperature is 1100°C, and the holding time is 2h;

[0051] The second temperature-controlled tubular vacuum furnace: starts heating from room temperature, the heating rate is 10°C / min, the target temperature is 700°C, and the holding time is 2 hours. It is used to condense indium fluoride gas. This temperature is set to prevent calcium, magnesium and water from cooling, and further purifies and dries the indium fluoride condensation product.

[0052] Place the graphite boat (open) in the first temperature-controlled tubular vacuum furnace, seal the temperature control device, turn on the vacuum pump, wait until the pressure drops to 5 Pa, pass pure argon gas for 5 minutes, turn off the argon gas, and keep the vacuum pump on;

[0053] The heating systems of two temperature-controlled tubular vacuum furnaces are turned on at the same time, and the temperature is kept at the target temperature for 2 hours to allow the indium fluoride, water, calcium and magnesium impurities in the acid leaching slurry to be completely gasified and separated from the tin oxide. At this time, the system pressure is 5 Pa;

[0054] After the vacuum distillation stage is completed, the system is cooled down naturally, and the indium fluoride solid is recovered on the surface of the graphite paper in the second temperature-controlled tubular vacuum furnace, and the tin oxide solid is recovered in the graphite boat.

[0055] The purity of the obtained tin oxide solid is >5N (99.999%), the purity of the indium fluoride solid is >4N (99.99%), the direct yield of the tin oxide solid is 99.8%, and the direct yield of the indium fluoride solid is 95%.

[0056] Example 2

[0057] The method and apparatus of Example 1 were used to prepare indium fluoride and tin oxide materials using ITO waste targets, except that the mass ratio of the powder of the ITO waste targets to the volume of hydrofluoric acid was reduced to 1 g:8 mL, and the other conditions were the same as in Example 1.

[0058] The results showed that the purity of the tin oxide solid obtained in Example 2 was 92%, because the indium oxide was not completely fluorinated and remained in the residue together with the tin oxide. The purity of the indium fluoride solid was >4N (99.99%), the direct yield of the tin oxide solid was 98%, and the direct yield of the indium fluoride solid was 95%.

[0059] Example 3

[0060] The method and apparatus of Example 1 were used to prepare indium fluoride and tin oxide materials using ITO waste targets, except that the temperature of the first temperature-controlled tubular vacuum furnace (i.e., the high-temperature distillation separation area) was set to 1000°C, and the remaining conditions were the same as in Example 1.

[0061] The results showed that the indium fluoride in the residue obtained in Example 3 was not completely vaporized and separated, indium fluoride accounted for about 10% of the tin oxide solid, the purity of the indium fluoride solid in the condensation zone was >4N (99.992%), the recovery rate of the tin oxide solid was 98%, and the direct recovery rate of the indium fluoride solid was reduced to 89%.

[0062] Example 4

[0063] The method and apparatus of Example 1 were used to prepare indium fluoride and tin oxide materials using ITO waste targets, except that the temperature of the second temperature-controlled tubular vacuum furnace (i.e., the indium fluoride condensation temperature) was set to 800°C, and the other conditions were the same as in Example 1.

[0064] The results showed that the purity of the tin oxide solid obtained in Example 4 was >5N (99.999%), the purity of the indium fluoride solid was >4N (99.992%), the direct yield of the tin oxide solid was 98%, and the direct yield of the indium fluoride solid dropped to 85% because the condensation temperature was too high, which hindered the condensation of indium fluoride.

[0065] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for recovering indium fluoride and tin oxide from ITO waste target, comprising the following steps: Using hydrofluoric acid to acid-leach the powder of the ITO waste target to obtain an acid-leach slurry, wherein the acid-leach slurry contains indium fluoride and tin oxide; The acid leaching slurry is subjected to vacuum distillation to obtain indium fluoride-containing gas and tin oxide solid respectively; the temperature of the vacuum distillation is 1000-1100° C.; the vacuum degree of the vacuum distillation is 5-20 Pa; The indium fluoride gas is subjected to vacuum condensation to obtain indium fluoride solid; the condensation temperature is 700-800° C.; The purity of the tin oxide solid is greater than 99.999%; the purity of the indium fluoride obtained by vacuum condensation is greater than 99.99%.

2. The method according to claim 1, characterized in that The mass concentration of the hydrofluoric acid is 40-50%.

3. The method according to claim 1 or 2, characterized in that: The mass ratio of the powder of the ITO waste target to the volume ratio of hydrofluoric acid is 1 g: (10-15) mL.

4. The method according to claim 1 or 2, characterized in that: The acid leaching temperature is 65-75° C. and the time is 1.5-2.5 hours.

5. The method according to claim 1 or 2, characterized in that: The mesh size of the powder of the ITO waste target is 100 to 200 meshes.

6. The method according to claim 1 or 2, characterized in that: The composition of the ITO waste target is In2O3 89.4%, SnO2 9.9%, Ca 0.6%, and Mg 0.1%.

7. The method according to claim 1, characterized in that The insulation time of the vacuum distillation is 1 to 2 hours.

8. The method according to claim 1, characterized in that The heat preservation time of the vacuum condensation is 1 to 2 hours.

9. The method according to claim 1 or 8, characterized in that: The vacuum degree of the vacuum condensation is 5-20Pa.

10. The method according to claim 1 or 7, characterized in that: The heating rate to the vacuum distillation temperature was 10° C. / min.

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