A method for efficiently recovering sponge indium and sponge tin from ITO waste targets

Abstract

The application discloses a method for efficiently recycling sponge indium and sponge tin by taking ITO waste targets as raw materials, and belongs to the technical field of resource recycling. The ITO waste targets are subjected to leaching treatment by hydrochloric acid to obtain leaching liquid and high-indium-content solution, indium pieces are added into the leaching liquid to displace solid tin, the solid tin is subjected to pickling treatment to obtain high-purity sponge tin, the pH of the high-indium-content solution is adjusted to be acidic, aluminum pieces are added, and the displacement product is subjected to water washing and drying to obtain high-purity sponge indium, so that the efficient recycling of the sponge indium and the sponge tin is realized.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology, and in particular relates to a method for efficiently recovering sponge-like indium and sponge-like tin from ITO waste targets. Background Technology

[0002] Indium tin oxide (ITO) is an N-type oxide semiconductor, formed by sintering a mixture of In₂O₃ and SnO₂ in a certain proportion. Indium and tin are the main raw materials for manufacturing ITO targets. Therefore, the resource utilization of waste ITO is of great practical significance for alleviating the supply and demand imbalance of indium and protecting the environment.

[0003] Patent CN 117845058 A relates to a method for recovering indium and tin from waste ITO targets. It proposes an acid-dissolution-hydrothermal precipitation-pH precipitation method based on a eutectic solvent to separate and recover indium and tin from the waste ITO targets. Although this method has mild reaction conditions and does not generate additional solid waste, the products obtained are oxides SnO2 and In2O3, which are not very advantageous for subsequent purification of metallic indium and tin, as they increase the number of reaction steps. Patent CN 112626343 A relates to a method for recovering metallic indium and tin from waste ITO targets, proposing the use of separate tin-removing reactors and indium-removing reactors to recover the two metals. Although this method can achieve separate recovery of the two metals and reduce resource waste, the indium loss rate in the tin removal process is 0.47%-0.5%, which is too high for indium loss after industrial production. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method for efficiently recovering sponge-like indium and sponge-like tin using waste ITO targets as raw materials.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for efficiently recovering spongy indium and spongy tin from ITO waste targets. The method involves leaching the ITO waste targets with hydrochloric acid to obtain a leachate and a high-indium-content solution. Indium flakes are added to the leachate to displace the spongy tin. The spongy tin is then acid-washed to obtain high-purity spongy tin. The pH of the high-indium-content solution is adjusted to acidic, aluminum flakes are added, and the displacement product is washed with water and dried to obtain high-purity spongy indium.

[0007] This invention uses waste ITO targets as raw materials and employs hydrochloric acid leaching to ensure that the valuable metals indium and tin exist in ionic form in the leaching solution. Indium flakes displace the spongy tin, and acid washing further recovers the indium adhering to the spongy tin, improving its purity. The acid-washed solution can be subjected to a second displacement. By adding water to adjust the pH of the displacement solution, aluminum flakes are added to displace the spongy indium. Further washing and drying yield high-purity spongy indium, thus achieving efficient recovery of indium and tin.

[0008] Furthermore, the method for efficiently recovering sponge-like indium and sponge-like tin from ITO waste targets includes the following steps:

[0009] (1) ITO waste target was leached with hydrochloric acid to obtain leachate and high indium content solution;

[0010] (2) The indium sheet is placed in the leaching solution and the spongy tin is displaced at 25-75°C;

[0011] (3) The sponge-like tin is obtained by acid washing and drying. The purity of the sponge-like tin can reach 99%. The acid washing liquid can be returned to step (2) for replacement.

[0012] (4) Add water to the high indium content solution, adjust the pH to 1-2, and place aluminum sheets for displacement. After washing and drying the displacement product, high-purity sponge indium is obtained, with a purity of up to 99.7%.

[0013] The principle of this invention is as follows: Tin impurity in the ITO leaching solution is removed by indium sheet displacement, without introducing new impurity elements. At room temperature, indium reacts slowly with cold dilute acid. By acid washing the displacement product, spongy tin, indium can be further recovered, increasing the indium recovery rate while reducing the indium content, thus enabling the recovery of high-purity spongy tin. In a high-indium-content solution, deionized water is added to adjust the pH, and spongy indium is prepared using aluminum sheet displacement. Since the impurity element content in the high-indium-content solution is almost negligible, the displaced spongy indium has high purity.

[0014] In step (1), before leaching the ITO waste target with hydrochloric acid, the step also includes crushing and grinding the ITO waste target to obtain ITO waste target powder.

[0015] In step (1), the particle size of the waste ITO target powder is ≤0.150 mm, preferably ≤0.100 mm, and more preferably ≤0.050 mm. When the particle size does not meet the requirements, it can be finely ground; and / or

[0016] The concentration of the hydrochloric acid is 4-10 mol / L, preferably 8-10 mol / L, and more preferably 8 mol / L.

[0017] The ratio of the ITO waste target powder to hydrochloric acid is 1g:(1-6)mL, preferably 1g:4mL.

[0018] In step (1), the leaching temperature is 40-100°C and the leaching time is 3-6 hours; preferably, the leaching temperature is 60-100°C and the leaching time is 3-5 hours; more preferably, the leaching temperature is 60°C and the leaching time is 3 hours.

[0019] In step (2), the replacement time is 2 to 5 hours.

[0020] In step (3), the acid used in the pickling is hydrochloric acid, the concentration of the hydrochloric acid is 0.2 to 1.2 mol / L, preferably 1 mol / L, the pickling time is 10 to 70 min, preferably 30 min, and the drying temperature is 40 to 60°C, preferably 50°C.

[0021] In step (4), the temperature of the displacement is 25-75°C and the displacement time is 2-5 hours, preferably the temperature of the displacement is 60°C and the displacement time is 3 hours.

[0022] In step (4), the drying temperature is 40-60°C, preferably 50°C.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects:

[0024] (1) In view of the current problem of recovering indium and tin from ITO waste targets, the present invention uses ITO waste targets as raw materials, and after leaching and replacement, acid washing and replacement, it can achieve efficient recovery of sponge-like indium and sponge-like tin.

[0025] (2) The present invention uses acid washing, which can effectively improve the purity of tin in sponge tin, and at the same time can recover the residual indium in sponge tin;

[0026] (3) The pickling solution used in this invention can be returned to the indium wafer to replace tin for a second replacement, avoiding the trouble of pickling solution treatment and improving the recovery rate of the two metals. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 This is a flowchart of the method for efficiently recovering sponge-like indium and sponge-like tin using waste ITO targets as raw materials according to the present invention;

[0029] Figure 2 Here is a SEM image of the spongy tin obtained in Example 1;

[0030] Figure 3 This is a SEM image of the spongy indium obtained in Example 1. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0037] All raw materials and reagents used in the embodiments of this invention were purchased commercially. As an example, indium sheets were purchased from Qinghe County Tengfeng Metal Materials Co., Ltd. (purity ≥ 9999.5%); aluminum sheets were purchased from Hefei Shushan District Zhengyinghao Metal Materials Store (purity ≥ 99.99%).

[0038] The flowchart of the method for efficiently recovering sponge-like indium and sponge-like tin using waste ITO targets as raw materials in this invention is as follows: Figure 1 As shown.

[0039] Embodiments of the present invention provide a method for efficiently recovering sponge-like indium and sponge-like tin using waste ITO targets as raw materials, comprising the following steps:

[0040] (1) ITO waste target was leached with hydrochloric acid to obtain leachate and high indium content solution;

[0041] (2) Place the indium sheet in the leaching solution and displace the spongy tin at 25-75°C;

[0042] (3) High-purity sponge tin is obtained by acid washing and drying. The purity of sponge tin can reach 99%. The acid washing solution can be returned to step (2) for replacement.

[0043] (4) Add water to the high indium content solution, adjust the pH to 1-2, and put in aluminum sheet for displacement. After washing and drying the displacement product, high purity spongy indium is obtained. The purity of spongy indium can reach 99.7%.

[0044] In an embodiment of the present invention, before leaching the ITO waste target with hydrochloric acid in step (1), the step further includes crushing and grinding the ITO waste target to obtain ITO waste target powder. The present invention first crushes and grinds the ITO waste target to facilitate hydrochloric acid leaching, so that its valuable metals indium and tin exist in the leaching solution in ionic form, thus ensuring the purity and recovery rate of the recovered sponge-like indium and sponge-like tin.

[0045] In embodiments of the present invention, the particle size of the ITO waste target powder is ≤0.150 mm, preferably ≤0.100 mm, and more preferably ≤0.050 mm. When the particle size does not meet the requirements, it can be finely ground. Smaller particle size helps hydrochloric acid to penetrate the ITO waste target powder more uniformly, resulting in a more uniform leaching reaction. Smaller particle size means a larger specific surface area, increasing the contact area between hydrochloric acid and the ITO waste target powder, thereby accelerating the leaching reaction. Due to the increased leaching rate, smaller particle size ITO waste target powder can usually achieve a higher leaching rate; and / or

[0046] The concentration of hydrochloric acid is 4–10 mol / L, preferably 8–10 mol / L, and more preferably 8 mol / L. At lower concentrations, less hydrogen ions are provided, resulting in a slower leaching rate and insufficient reaction kinetics, leading to a slower dissolution rate of indium and tin in the waste ITO target powder. Higher concentrations may generate byproducts (such as chlorides). Appropriate concentrations of hydrochloric acid can provide sufficient hydrogen ions, enhancing the dissolution capacity of the waste ITO target powder and enabling rapid and complete dissolution of indium and tin.

[0047] In an embodiment of the present invention, the ratio of ITO waste target powder to hydrochloric acid is 1g:(1-6)mL, preferably 1g:4mL.

[0048] In an embodiment of the present invention, in step (1), the leaching temperature is 40-100°C and the leaching time is 3-6 hours; preferably, the leaching temperature is 60-100°C and the leaching time is 3-5 hours; more preferably, the leaching temperature is 60°C and the leaching time is 3 hours.

[0049] In an embodiment of the present invention, the displacement time in step (2) is 2–5 hours. If the displacement temperature is too low, the reaction rate is slow, the displacement efficiency is low, and the tin displacement may be incomplete; if the displacement temperature is too high, side reactions may occur, such as the generation of hydrogen gas, which not only reduces the utilization rate of zinc but may also increase energy consumption. The appropriate displacement temperature and time of the present invention can accelerate the reaction rate, improve the displacement efficiency, ensure a complete displacement reaction, and save energy.

[0050] In an embodiment of the present invention, in step (3), the acid used for pickling is hydrochloric acid, the concentration of hydrochloric acid is 0.2 to 1.2 mol / L, preferably 1 mol / L, the pickling time is 10 to 70 min, preferably 30 min, and the drying temperature is 40 to 60°C, preferably 50°C.

[0051] In an embodiment of the present invention, in step (4), the temperature of the displacement is 25-75°C and the displacement time is 2-5 hours, preferably the temperature of the displacement is 60°C and the displacement time is 3 hours.

[0052] In an embodiment of the present invention, in step (4), the drying temperature is 40-60°C, preferably 50°C.

[0053] In the following embodiments and comparative examples of the present invention, the Sn content in the ITO waste targets is 6.16-8.66% and the O content is 9.70-14.20% by mass, with the balance being In and unavoidable impurities.

[0054] In the following embodiments and comparative examples of the present invention, the substitution rate of the elements is calculated as shown in formula (1):

[0055]

[0056] In equation (1): R is the displacement rate, %; C0 is the initial content of the element, g / L; V0 is the initial volume of the solution, L; C t V represents the content of the element at reaction time t, in g / L. t Let L be the volume of the solution after displacement.

[0057] The recovery rate of tin can be calculated using formula (1). In the displacement impurity removal stage, In is lost in solid form. In the displacement of spongy indium stage, In is lost in liquid form. Therefore, the recovery rate of indium is calculated using formula (2):

[0058] η0=η1×η2 (2)

[0059] In equation (2): η0 is the total recovery rate of In, %; η1 is the recovery rate of In during displacement purification, %; η2 is the displacement rate of In during the preparation of sponge indium, %.

[0060] Spongy indium and tin are both semi-finished products, and currently there are no existing industry standards for their measurement. Therefore, their purity is determined by the difference method. Since the impurity element content in spongy indium and tin is low, inductively coupled plasma mass spectrometry (ICP-MS) is used to measure the impurity element content. The purity of the spongy indium and tin is then obtained by subtracting the impurity element content from 1. ICP-MS is an analytical instrument that combines inductively coupled plasma technology with mass spectrometry, primarily used for elemental analysis and quantitative measurement. By converting the sample into ions and separating them according to their mass-to-charge ratio, quantitative elemental analysis is achieved, with detection limits reaching 1 ppt or less.

[0061] It should be noted that all aspects not described in detail in this invention are conventional operating methods in the field and are not the focus of this invention. For example, specific methods such as crushing and grinding are all completed using conventional methods.

[0062] The technical solution of the present invention will be further illustrated by the following embodiments.

[0063] Example 1

[0064] This embodiment provides a method for efficiently recovering spongy indium and spongy tin using waste ITO targets as raw materials. The specific steps are as follows:

[0065] (1) The waste ITO target is crushed and ground to make the particle size of the waste ITO target ≤0.050mm, and the waste ITO target powder is obtained. 50g of waste ITO target powder is mixed with 8mol / L hydrochloric acid, the solid-liquid ratio is 1g:4mL, and the reaction is carried out at 90℃ for 5h to obtain leachate.

[0066] (2) Heat the leaching solution in step (1) to 60°C, add indium sheet, react for 3 hours, and displace the spongy tin.

[0067] (3) The spongy tin displaced in step (2) is pickled with hydrochloric acid at a concentration of 1 mol / L for 30 min. After drying at 50°C, a spongy tin with high purity is obtained.

[0068] (4) Return the pickling solution generated after pickling in step (3) to step (2) for replacement;

[0069] (5) Add water to the high indium content solution after displacement in step (2) to adjust the pH to 2, heat to 60°C, put in aluminum sheet, react for 3 hours, and displace spongy indium.

[0070] (6) The displaced sponge indium is washed with water and dried at 50°C to obtain sponge indium with higher purity.

[0071] The recovery rates of indium and tin were tested. The indium recovery rate reached 99.79%, with a purity of 99.7% for the sponge-like indium. The tin recovery rate reached 99.88%, with a purity of 99% for the sponge-like tin. SEM images of the sponge-like tin and sponge-like indium obtained in this embodiment are shown below. Figure 2 and Figure 3 As shown, the typical characteristics of sponge-like metals are loose and porous. The SEM image clearly shows that the product obtained by this invention is indeed a sponge-like metal.

[0072] Comparative Example 1: No acid pickling treatment was performed on the spongy tin.

[0073] This comparative example provides a method for recovering spongy indium and spongy tin from waste ITO targets. The specific steps are as follows:

[0074] (1) The waste ITO target is crushed and ground to make the particle size of the waste ITO target ≤0.050mm, and the waste ITO target powder is obtained. 50g of waste ITO target powder is mixed with 8mol / L hydrochloric acid, the solid-liquid ratio is 1g:4mL, and the reaction is carried out at 90℃ for 5h to obtain leachate.

[0075] (2) Heat the leaching solution in step (1) to 60°C, add indium sheet, react for 3 hours, and displace the spongy tin.

[0076] (3) Add water to the high indium content solution after displacement in step (2) to adjust the pH to 2, heat to 60°C, put in aluminum sheet, react for 3 hours, and displace spongy indium.

[0077] (4) After the replacement sponge indium is washed with water and dried, a sponge indium with higher purity is obtained.

[0078] The recovery rates of indium and tin were tested. The recovery rate of indium was 98.2%, and the purity of sponge indium was 99.7%. The recovery rate of tin was 93.45%, and the purity of sponge tin was 93%.

[0079] In Comparative Example 1, the displaced sponge tin was not treated in any way, and indium was lost in solid form within the sponge tin, thus reducing the overall indium recovery rate.

[0080] Comparative Example 2: Adjusting the pH of ITO waste target leachate

[0081] This comparative example provides a method for recovering spongy indium and spongy tin from waste ITO targets. The specific steps are as follows:

[0082] (1) The waste ITO target is crushed and ground to make the particle size of the waste ITO target ≤0.050mm, and the waste ITO target powder is obtained. 50g of waste ITO target powder is mixed with 8mol / L hydrochloric acid, the solid-liquid ratio is 1g:4mL, and the reaction is carried out at 90℃ for 5h to obtain leachate.

[0083] (2) Adjust the pH of the leachate from step (1) to 1 using ammonia water;

[0084] (3) Heat the leaching solution in step (2) to 60°C, add indium sheet, react for 3 hours, and displace the spongy tin.

[0085] (4) Add water to adjust the pH of the high indium content solution after replacement in step (3) to 2, heat the leaching solution to 60°C, put in aluminum sheets, react for 3 hours, and replace the spongy indium.

[0086] (5) After the replacement sponge indium is washed with water and dried, a sponge indium with higher purity is obtained.

[0087] The recovery rates of indium and tin were tested. The recovery rate of indium was 99.2%, and the purity of sponge indium was 99.5%. The recovery rate of tin was 11.10%, and the purity of sponge tin was 99.3%.

[0088] In Comparative Example 2, the pH of the leaching solution was adjusted using ammonia. The presence of a certain acid concentration in the solution can promote the forward reaction of tin removal by displacement. After adjusting the pH, the reaction rate will slow down, which is not conducive to the occurrence of the tin removal reaction.

[0089] Example 2

[0090] This embodiment provides a method for efficiently recovering spongy indium and spongy tin using waste ITO targets as raw materials. The specific steps are as follows:

[0091] (1) The waste ITO target is crushed and ground to make the particle size of the waste ITO target ≤0.050mm, and the waste ITO target powder is obtained. 50g of waste ITO target powder is mixed with 10mol / L hydrochloric acid, the solid-liquid ratio is 1g:1mL, and the reaction is carried out at 100℃ for 3h to obtain leachate.

[0092] (2) Heat the leaching solution in step (1) to 75°C, add indium sheet, react for 2 hours, and displace the spongy tin.

[0093] (3) The spongy tin displaced in step (2) is pickled with hydrochloric acid at a concentration of 0.2 mol / L for 30 min. After drying at 60°C, a spongy tin with high purity is obtained.

[0094] (4) Return the pickling solution generated after pickling in step (3) to step (2) for replacement;

[0095] (5) Add water to the high indium content solution after displacement in step (2) to adjust the pH to 2, heat to 75°C, put in aluminum sheet, react for 2 hours, and displace spongy indium.

[0096] (6) The displaced sponge indium is washed with water and dried at 40°C to obtain sponge indium with high purity.

[0097] The recovery rates of indium and tin were tested. The recovery rate of indium reached 99.25%, and the purity of sponge indium was 99.7%. The recovery rate of tin reached 98.65%, and the purity of sponge tin was 98%.

[0098] Example 3

[0099] This embodiment provides a method for efficiently recovering spongy indium and spongy tin using waste ITO targets as raw materials. The specific steps are as follows:

[0100] (1) The waste ITO target was crushed and ground to make the particle size of the waste ITO target ≤0.150mm, and the waste ITO target powder was obtained. 50g of waste ITO target powder was mixed with 4mol / L hydrochloric acid, the solid-liquid ratio was 1g:6mL, and the reaction was carried out at 40℃ for 6h to obtain leachate.

[0101] (2) Heat the leaching solution in step (1) to 25°C, add indium sheet, react for 5 hours, and displace the spongy tin.

[0102] (3) The spongy tin displaced in step (2) is acid-washed with hydrochloric acid at a concentration of 1.2 mol / L for 10 min. After drying at 40°C, a spongy tin with high purity is obtained.

[0103] (4) Return the pickling solution generated after pickling in step (3) to step (2) for replacement;

[0104] (5) Add water to the high indium content solution after displacement in step (2) to adjust the pH to 1, heat to 25°C, put in aluminum sheet, react for 5 hours, and displace spongy indium.

[0105] (6) The displaced sponge indium is washed with water and dried at 60°C to obtain sponge indium with high purity.

[0106] The recovery rates of indium and tin were tested. The recovery rate of indium reached 99.55%, and the purity of sponge indium was 99.7%. The recovery rate of tin reached 99.1%, and the purity of sponge tin was 99%.

[0107] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for efficiently recovering sponge-like indium and sponge-like tin from ITO waste targets, characterized in that, Includes the following steps: (1) The waste ITO target was leached with hydrochloric acid to obtain a leachate; (2) The indium sheet is placed in the leaching solution and the spongy tin and high indium content solution are displaced at 25~75 °C; (3) The sponge-like tin is obtained by acid washing and drying to obtain high-purity sponge-like tin with a purity of 99%; (4) Water is added to the high indium content solution to adjust the pH to 1-2, and aluminum sheets are added for displacement. After washing and drying, high-purity sponge-like indium is obtained with a purity of 99.7%. In step (1), the leaching temperature is 40~100 ℃ and the leaching time is 3~6 h; In step (2), the replacement time is 2~5 hours; In step (4), the temperature of the displacement is 25~75 ℃ and the displacement time is 2~5 h.

2. The method for efficiently recovering sponge-like indium and sponge-like tin from ITO waste targets according to claim 1, characterized in that, In step (1), before leaching the ITO waste target with hydrochloric acid, the step also includes crushing and grinding the ITO waste target to obtain ITO waste target powder.

3. The method for efficiently recovering spongy indium and spongy tin from ITO waste targets according to claim 2, characterized in that, In step (1), the particle size of the ITO waste target powder is ≤0.150 mm; and / or The concentration of the hydrochloric acid is 4~10 mol / L.

4. The method for efficiently recovering sponge-like indium and sponge-like tin from ITO waste targets according to claim 2, characterized in that, The ratio of the ITO waste target powder to hydrochloric acid is 1g:(1~6)mL.

5. The method for efficiently recovering spongy indium and spongy tin from ITO waste targets according to claim 1, characterized in that, In step (3), the acid used for pickling is hydrochloric acid, the concentration of the hydrochloric acid is 0.2~1.2 mol / L, the pickling time is 10~70 min, and the drying temperature is 40~60 ℃.

6. The method for efficiently recovering sponge-like indium and sponge-like tin from ITO waste targets according to claim 1, characterized in that, In step (4), the drying temperature is 40~60℃.

Images