A method for leaching indium and tin from ITO conductive glass powder

Abstract

The application relates to the technical field of ITO conductive glass recycling, and discloses a method for leaching and separating indium and tin in ITO conductive glass powder, which comprises the following steps: mixing ITO conductive glass powder with a leaching agent solution to obtain leaching ore slurry; wherein the leaching agent solution is prepared by using oxalic acid, reagent A, reagent B and water; the reagent A is an oxalate, and the reagent B is one of sodium sulfide, ammonium sulfide and TAA; the leaching ore slurry is subjected to stirring leaching, and after leaching reaction, filtration separation is carried out to obtain leaching residue and leaching liquid; the leaching liquid is subjected to hydrolysis and indium precipitation reaction, and after reaction, filtration is carried out to obtain indium precipitation filtrate and indium residue; the method has the advantages of good leaching selectivity, fast indium leaching speed, high leaching rate and low energy consumption in the leaching process, and the indium leaching rate is much higher than that in traditional oxalic acid leaching.

Description

Technical Field

[0001] This invention belongs to the field of urban solid electronic waste resource utilization technology, and specifically relates to a method for leaching and separating indium and tin from ITO conductive glass powder. Background Technology

[0002] Indium Tin Oxides (ITO) are composed of indium oxide and tin oxide, typically in a 9:1 mass ratio. It is an excellent transparent conductive material widely used in electronic displays, solar cells, and LEDs. With the rapid development of electronic information technology, the consumption of ITO targets, a raw material for producing indium tin oxide thin films, has increased significantly, while indium's natural resources are limited. Therefore, against the backdrop of increasing indium demand and the continuous increase in the amount of waste ITO conductive glass, the recycling of waste ITO targets after magnetron sputtering and waste ITO conductive glass has become a major source of recycled indium. The recovery of indium from waste ITO targets and waste ITO conductive glass is of great significance for alleviating the supply and demand imbalance of indium resources, reducing production costs, and reducing environmental pollution. Effective recovery of indium from waste ITO targets and waste ITO conductive glass has become an important link in the ITO industry chain.

[0003] Currently, the main methods for recovering indium from waste palladium and waste ITO conductive glass are dry and wet methods. The dry methods include high-temperature pyrolysis, high-temperature reduction and chlorination volatilization, while the high-temperature reduction methods include atmospheric pressure carbothermal reduction, vacuum carbothermal reduction and hydrogen reduction. The wet methods mainly include inorganic acid method and oxalic acid method.

[0004] Specifically, while high-temperature pyrolysis processes at low temperatures, the decomposition product is an indium-tin alloy, requiring further separation of indium and tin through vacuum distillation or wet electrolysis. Vacuum carbothermal reduction, though at a lower temperature than atmospheric pressure carbothermal reduction, places high demands on equipment. Hydrogen reduction, while eliminating carbon emissions, also suffers from high energy consumption and low reduction efficiency. Reduction methods, despite their short process and simple operation, produce an indium-tin alloy as the final product, resulting in poor separation of indium and tin during reduction, necessitating further separation through vacuum distillation or wet electrolysis. Chlorination volatilization, while offering high indium recovery, short volatilization time, and lower chlorination temperatures than thermal reduction, generates highly corrosive and toxic chloride-containing tail gas, requiring a chloride-containing tail gas treatment system. Furthermore, it suffers from complex processes, high chlorination reaction temperatures, and high energy consumption.

[0005] When separating indium and tin using wet leaching, the main leaching agents include hydrochloric acid, sulfuric acid, nitric acid, and inorganic mixed acids. Among these, the inorganic acid method has advantages such as short leaching time, low energy consumption, and no harmful fumes. However, this method has a low leaching pH, poor separation effect of indium and tin, and strong corrosiveness. In addition, nitric acid and hydrochloric acid are volatile during application, and the working conditions are also poor. Oxalic acid has advantages such as short leaching time, high indium leaching rate, and better separation effect of indium and tin than carbothermal reduction and inorganic acid methods. However, when using oxalic acid to separate indium and tin from waste ITO glass powder, the high quartz content causes the formation of a solid film during the leaching process, resulting in a low indium leaching rate. Furthermore, the separation effect of indium and tin needs to be further improved. Therefore, there is an urgent need to develop a clean production technology for separating indium and tin from waste ITO glass with good leaching selection, high indium leaching rate, and environmental friendliness. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for leaching and separating indium and tin from ITO conductive glass powder, thereby solving the problems of low indium leaching rate and poor separation effect of indium and tin due to low leaching pH in existing oxalic acid leaching methods for separating indium and tin from ITO conductive glass powder.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a method for leaching and separating indium and tin from ITO conductive glass powder, comprising:

[0009] ITO conductive glass powder is mixed with a leaching agent solution to obtain a leaching slurry; wherein the leaching agent solution is prepared with oxalic acid, reagent A, reagent B and water; reagent A is oxalate and reagent B is a sulfiding agent;

[0010] The leaching slurry is stirred and leached. After the leaching reaction is completed, it is filtered and separated to obtain leaching residue and leaching solution.

[0011] The leachate was subjected to a hydrolysis reaction to precipitate indium. After the reaction was completed, the solution was filtered to obtain indium precipitate filtrate and indium residue.

[0012] Furthermore, in the leaching slurry, the liquid-to-solid ratio of the leaching agent solution to the ITO conductive glass powder is (6-10) mL / g.

[0013] Furthermore, the oxalate is one of sodium oxalate, ammonium oxalate, and potassium oxalate; and the reagent B is one of sodium sulfide, ammonium sulfide, and TAA.

[0014] Furthermore, in the leaching agent solution, the molar mass ratio of oxalic acid to oxalate is (2-1):(1-2), and c(C2O4)2- ) T The molar concentration is 0.10-0.18 mol / L; the amount of reagent B added is 0.02%-0.1% of the weight of the ITO conductive glass powder.

[0015] Furthermore, when the leaching slurry is stirred and leached, the leaching temperature is 60-90℃ and the stirring and leaching time is 20-60 minutes.

[0016] Furthermore, the process of hydrolyzing the leachate to precipitate indium and obtaining an indium-precipitated solution is as follows:

[0017] After adding indium hydrolysis precipitating reagent C to the leachate, an indium hydrolysis precipitating reaction is carried out. After the reaction is completed, the solution is filtered to obtain indium precipitating filtrate and indium residue.

[0018] Furthermore, the indium hydrolysis precipitation reagent C is one of NaOH, NH3∙H2O and KOH, and the final pH of the indium hydrolysis precipitation reaction is between 8 and 11; the indium slag is indium slag containing In(OH)3.

[0019] Furthermore, the indium precipitation filtrate is diverted; a portion of the indium precipitation filtrate is returned to the leaching slurry preparation step for conditioning the leaching slurry; the other portion of the indium precipitation filtrate is used as a raw material for regenerating oxalate.

[0020] Furthermore, in the leaching solution, the leaching rate of indium is 82.68%-97.74%.

[0021] Furthermore, the particle size of the ITO conductive glass powder is less than 0.75 μm.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention provides a method for leaching and separating indium and tin from ITO conductive glass powder. A mixed solution of oxalic acid, reagent A, and reagent B is used as the leaching agent to leach indium from waste ITO conductive glass, while tin remains in the leaching residue, thus achieving separation of indium and tin. During the separation process, the addition of reagents A and B ensures rapid complexation and leaching of indium at a higher pH, while simultaneously inhibiting tin leaching. This method offers advantages such as rapid indium leaching, high indium leaching rate, and good separation of indium and tin. Furthermore, the indium leaching rate is higher than that achieved when leaching waste ITO conductive glass powder with oxalic acid. The addition of reagent B not only inhibits tin leaching but also reduces and inhibits iron leaching, achieving the purpose of purifying the leaching solution and improving the purity of In(OH)3 obtained from hydrolysis and precipitation of indium. In addition, oxalic acid and reagent A are environmentally friendly reagents and are both solids, making their storage, handling, and transportation convenient.

[0024] Furthermore, the liquid-to-solid ratio of the leaching agent solution to the waste ITO conductive glass powder was controlled at (6-10) mL / g. Within this liquid-to-solid ratio range, changes in water volume have a minimal impact on the pH value of the leaching slurry, ensuring that In₂O₃ in the waste ITO conductive glass powder can be leached with oxalic acid to obtain In. 3+ , leachate In 3+ Then with C2O4 2- Complexation was performed, which increased the leaching rate of indium.

[0025] Furthermore, in the leaching agent solution, the molar ratio of oxalic acid to reagent A is controlled at (2-1):(1-2), and c(C2O4) 2- ) T The molar concentration of In was controlled at 0.10-0.50 mol / L to ensure that In 3+ To form In(C2O4)3 with a large cumulative stability constant in the leachate. 3- At the same time, excessive free C2O4 2- The presence of In(C2O4)3 can also make 3- The wider pH range of stable existence facilitates pH control during the leaching process and enhances the stability of In(C2O4)3. 3- Improved stability in the leaching solution, thus increasing the leaching rate of indium. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The image shown is an electron microscope image of the ITO glass powder in Example 1.

[0028] Figure 2 This is an electron microscope image of the leaching residue from Example 1. Detailed Implementation

[0029] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0031] This invention provides a method for leaching and separating indium and tin from ITO conductive glass powder, comprising the following steps:

[0032] Step 1: Add water, oxalic acid, reagent A, and reagent B to the leaching tank and stir to dissolve, obtaining a leaching agent solution; wherein, reagent A is oxalate, and the molar mass ratio of oxalic acid to oxalate is (2-1):(1-2), and c(C2O4) 2- ) T The molar concentration is 0.10-0.18 mol / L; preferably, the oxalate is one of sodium oxalate, ammonium oxalate and potassium oxalate; the reagent B is one of sodium sulfide, ammonium sulfide and TAA, and the amount of reagent B added is 0.02%-0.1% of the weight of ITO conductive glass powder.

[0033] Step 2: Stir the leaching agent solution and add ITO conductive glass powder during the stirring process to obtain a leaching slurry; wherein, in the leaching slurry, the liquid-to-solid ratio of the leaching agent solution to the ITO conductive glass powder is (6-10) mL / g, and the particle size of the ITO conductive glass powder is less than 0.75 μm.

[0034] Step 3: Stir and leach the leaching slurry. After the leaching process is completed, filter and separate to obtain leaching residue and leaching solution. During stirring leaching, the leaching temperature is 60-90℃ and the stirring leaching time is 20-60min.

[0035] Step 4: After adding the indium hydrolysis precipitating reagent to the leachate, perform the indium hydrolysis precipitating reaction. After the reaction is completed, filter to obtain indium precipitated filtrate and indium slag. The indium hydrolysis precipitating reagent C is one of NaOH, NH3∙H2O and KOH, and the pH of the indium hydrolysis precipitating reaction is 8-11. The indium slag is indium slag containing In(OH)3.

[0036] Step 5: The indium precipitate filtrate is diverted; a portion of the indium precipitate filtrate is returned to the process of preparing the leaching slurry in Step 2 for conditioning the leaching slurry; the other portion of the indium precipitate filtrate is used as raw material for regenerating reagent A.

[0037] The principle of separating indium and tin:

[0038] The method for leaching and separating indium and tin from ITO conductive glass according to the present invention involves mixing oxalic acid, reagent A, and reagent B to prepare a leaching agent solution. This leaching agent solution is then mixed with waste ITO conductive glass powder to obtain a leaching slurry. After stirring and reacting the leaching slurry, selective leaching of indium and separation of indium and tin from the ITO conductive glass can be achieved. During the stirring leaching reaction, C2O4... 2- For In 3+ It exhibits strong complexation to form In(C2O4)3 with a large cumulative stability constant. 3- The complexation leaching of In2O3 in ITO conductive glass has the advantages of good leaching selectivity, fast indium leaching speed, high indium leaching rate, good indium-tin separation effect and low energy consumption in the leaching process; in addition, oxalic acid and reagent A are both environmentally friendly reagents and are both solids, which are convenient to store, transport and handle.

[0039] Specifically, the leaching solution is a mixture of oxalic acid, reagent A, and reagent B. Reagent A in the mixture plays two roles in the leaching process: firstly, it provides complexation for In. 3+ C2O4 2- Secondly, adjust the pH value of the leaching system; because In 3+ With C2O4 2- In(C2O4) with different cumulative stability constants can be formed. + In(C2O4)2 - and In(C2O4)3 3- Among them, In(C2O4)3 3- The cumulative stability constant is the largest; while the leached In 3+ The specific form of the indium oxalate complex present in the leachate depends on the final pH value of leaching and the concentration of C2O4. 2- ) T Concentration; In this invention, the molar ratio of oxalic acid to reagent A is controlled at (2-1):(1-2), and c(C2O4) 2- ) T The molar concentration was controlled at 0.10-0.18 mol / L to ensure the leaching of In. 3+ Convert it into In(C2O4)3 with a large cumulative stability constant as much as possible. 3- This effectively improves the indium leaching rate and shortens the indium leaching time.

[0040] In this invention, a mixed reagent prepared with oxalic acid, reagent A, and reagent B is used to leach In₂O₃ from ITO conductive glass. This process enhances the coordination leaching of In₂O₃ while simultaneously inhibiting the acid leaching of soluble metallic tin and α-SnO₂. Furthermore, the addition of reagent B further enhances the leaching of Sn. 2+The conversion to SnS2 precipitate and reduction inhibit the leaching of iron, leaving tin in the leaching residue. This is beneficial for the recovery of tin from the leaching residue and improves the tin recovery rate. The glass residue after tin recovery can also be reused.

[0041] Example 1

[0042] This embodiment 1 provides a method for leaching and separating indium and tin from ITO conductive glass powder, including the following steps:

[0043] Step 1: Add water, oxalic acid, sodium oxalate, and sodium sulfide to a leaching tank, stir to dissolve, and obtain a leaching agent solution; wherein the molar ratio of oxalic acid to sodium oxalate is 1.4:1.6, and c(C2O4) 2- ) T The molar concentration was 0.10 mol / L, and the amount of sodium sulfide added was 0.02% of the weight of the ITO glass powder.

[0044] Step 2: Add 10g of ITO conductive glass powder to 100mL of the leaching agent solution and stir to obtain a leaching slurry; wherein, an electron microscope image of the ITO conductive glass powder is attached. Figure 1 As shown.

[0045] Step 3: The leaching slurry is stirred and leached at 90℃ for 60 minutes. After the leaching reaction is complete, it is filtered to obtain leaching residue and leachate; the electron micrograph of the leaching residue is attached. Figure 2 As shown.

[0046] Step 4: Add a 50% NaOH solution to the leachate and carry out a hydrolysis precipitation reaction to obtain an indium precipitation solution after the reaction is completed; wherein, the pH of the hydrolysis precipitation reaction is 8.

[0047] Step 5: Filter and separate the indium precipitation solution to obtain indium slag and indium precipitation filtrate; wherein the indium slag is indium slag containing In(OH)3.

[0048] Step 6: The indium precipitate filtrate is diverted; a portion of the indium precipitate filtrate is returned to the leaching slurry preparation step for slurry conditioning; the other portion of the indium precipitate filtrate is used as a raw material for regenerating sodium oxalate.

[0049] Results and test instructions:

[0050] The indium and tin content in the ITO conductive glass powder was detected, as was the indium and tin content in the mixed solution, which was a combined solution of leaching solution and leaching residue washing solution with a total volume of 250 mL. The results showed that in Example 1, the leaching rates of indium and tin were 95.74% and 0.25%, respectively.

[0051] Example 2

[0052] The method for leaching and separating indium and tin from ITO conductive glass powder provided in Example 2 is basically the same in steps and principle as the method for leaching and separating indium and tin from ITO conductive glass powder described in Example 1 above, except that:

[0053] In step 1, sodium oxalate is replaced with ammonium oxalate, and the molar ratio of oxalic acid to ammonium oxalate is 2:1. Sodium sulfide is also replaced with ammonium sulfide. In step 4, a 30% NH3∙H2O solution is added to the leachate to adjust the pH of the leachate to 10 for indium hydrolysis precipitation. After the reaction is complete, an indium precipitation solution is obtained. The remaining steps are basically the same and will not be described in detail here.

[0054] Results and test instructions:

[0055] In Example 2, when the molar ratio of oxalic acid to ammonium oxalate is 2:1, 100 mL of c(C2O4) solution containing 0.10 mol / L is used. 2- ) T When 10g of waste ITO conductive glass was leached for 60min at 90℃ with an ammonium sulfide solution containing 0.05% by weight of ITO glass powder, the leaching rates of indium and tin were 92.68% and 0.47%, respectively.

[0056] Example 3

[0057] The method for leaching and separating indium and tin from ITO conductive glass powder provided in Example 3 is basically the same in steps and principle as the method for leaching and separating indium and tin from ITO conductive glass powder described in Example 1 above, except that:

[0058] In step 1, sodium oxalate is replaced with potassium oxalate, and the molar ratio of oxalic acid to potassium oxalate is 1:2. Sodium sulfide is replaced with TAA. In step 4, a 50% KOH solution is added to the leachate to adjust the pH of the leachate to 8.5 for indium hydrolysis precipitation reaction. After the reaction is completed, an indium precipitation solution is obtained. The remaining steps are basically the same and will not be described in detail here.

[0059] Results and test instructions:

[0060] In Example 3, when the molar ratio of oxalic acid to potassium oxalate is 1:2, 100 mL of c(C2O4) solution containing 0.10 mol / L is used. 2- ) T When 10g of waste ITO glass was leached with TAA containing 0.10% by weight of ITO glass powder at 90°C for 60min, the leaching rates of indium and tin were 91.41% and 0.11%, respectively.

[0061] Example 4

[0062] The method for leaching and separating indium and tin in ITO conductive glass powder provided in Example 4 is basically the same in steps and principle as the indium leaching method for ITO conductive glass described in Example 1 above, except that:

[0063] In step 1, the c(C2O4) 2- ) T The molar concentration is 0.18 mol / L, and sodium sulfide is replaced with TAA; in step 3, the leaching slurry is stirred and leached at 70°C; in step 4, a 50% KOH solution is added to the leaching solution to adjust the pH of the leaching solution to 8.5 for hydrolysis and indium precipitation reaction, and an indium precipitation solution is obtained after the reaction is completed; the remaining steps are basically the same and will not be described in detail here.

[0064] Results and test instructions:

[0065] In Example 4, when the molar ratio of oxalic acid to potassium oxalate was 1:2, 100 mL of c(C2O4) solution containing 0.18 mol / L was used. 2- ) T When 10g of waste ITO glass was leached with a TAA solution containing 0.10% by weight of ITO glass powder at 70°C for 60min, the leaching rates of indium and tin were 92.35% and 0.16%, respectively.

[0066] Example 5

[0067] The method for leaching and separating indium and tin from ITO conductive glass powder provided in Example 5 is basically the same in steps and principle as the leaching method for separating indium and tin from ITO conductive glass described in Example 1 above, except that:

[0068] In step 1, the c(C2O4) 2- ) T The molar concentration is 0.90 mol / L; in step 2, the liquid-to-solid ratio of the leaching slurry is 6 mL / g; in step 4, a 50% NaOH solution is added to the leaching solution to adjust the pH of the leaching solution to 9 for hydrolysis and indium precipitation reaction, and an indium precipitation solution is obtained after the reaction is completed; the remaining steps are basically the same and will not be described in detail here.

[0069] Results and test instructions:

[0070] In Example 5, when the molar ratio of oxalic acid to sodium oxalate in the leaching agent solution is 1.4:1.6, the volume is 60 mL, containing 0.18 mol / L c(C2O4) 2- ) TWhen 10g of waste ITO glass was leached with sodium sulfide containing 0.03% by weight of ITO glass powder at 90°C for 60min, the leaching rates of indium and tin were 95.18% and 0.18%, respectively.

[0071] Example 6

[0072] The method for leaching and separating indium and tin from ITO conductive glass powder provided in Example 6 is basically the same in steps and principle as the method for leaching and separating indium and tin from ITO conductive glass described in Example 1 above, except that:

[0073] In step 1, the c(C2O4) 2- ) T The molar concentration is 0.18 mol / L; in step 2, the liquid-to-solid ratio of the leaching slurry is 10 mL / g; in step 3, the stirring leaching time is 20 min; in step 4, a 50% sodium sulfide solution is added to the leaching solution to adjust the pH of the leaching solution to 10 for hydrolysis and indium precipitation reaction, and an indium precipitation solution is obtained after the reaction is completed; the remaining steps are basically the same and will not be described in detail here.

[0074] Results and test instructions:

[0075] In Example 6, when the molar ratio of oxalic acid to sodium oxalate in the leaching agent solution is 1.4:1.6, the volume is 100 mL and contains 0.18 mol / L c(C2O4) 2- ) T When 10g of waste ITO glass was leached with sodium sulfide containing 0.08% by weight of ITO glass powder at 90℃ for 20min, the leaching rate of indium was 95.07%, while tin was not leached.

[0076] This invention discloses a method for leaching and separating indium and tin from ITO conductive glass powder. A leaching agent solution is prepared using oxalic acid, reagent A, reagent B, and water. This solution is used to leach In₂O₃ from the ITO conductive glass while simultaneously inhibiting the leaching of tin and iron. The leaching slurry is separated to obtain a leaching solution and a leaching residue. The leaching solution is then subjected to a hydrolysis reaction to precipitate indium and to separate indium residue and reagent A solution. This method features rapid indium leaching, high indium leaching rate, good separation of indium and tin, low energy consumption during the leaching and separation process, simple leaching equipment, minimal environmental pollution, and ease of industrialization.

[0077] In this invention, the leaching agent solution is a mixed reagent prepared with oxalic acid, reagent A, reagent B, and water. The oxalic acid in the mixed reagent is used to leach In₂O₃ from the ITO conductive glass powder to produce In. 3+ Reagent A was used to increase the leaching pH, and C2O4 was used... 2- For In 3+It has a strong complexing effect, making the leached In... 3+ Transformed into In(C2O4)3 with a large cumulative stability constant 3- To enhance the complexation leaching of indium, increasing the leaching pH can also inhibit the leaching of tin; the addition of reagent B can improve the leaching of Sn. 2+ Indium and tin are precipitated and enriched in the leaching residue in the form of SnS precipitate, which improves the separation effect of indium and tin and also helps to increase the recovery rate of tin in the leaching residue.

[0078] In this invention, the liquid-to-solid ratio of the leaching agent solution to the ITO conductive glass powder is controlled at 6-10 mL / g. Within this liquid-to-solid ratio range, changes in liquid volume have little effect on the pH value of the leaching slurry. The pH value of the leaching slurry is mainly achieved by adjusting the molar ratio of oxalic acid and reagent A. Specifically, for In₂O₃ in the ITO conductive glass, the In produced during leaching should be... 3+ In(C2O4)3 is completely formed in the leachate. 3- Then n(C2O4) 2- ) T / n(In 3+ ) T Molar ratio ≥ 3:1, n(C2O4) in the leaching agent solution 2- The larger the molar number, that is, the higher the concentration of C2O4 in the leachate. 2- ) T The higher the concentration, the greater the driving force of the In₂O₃ leaching process, and the better the leaching effect of indium; and the more excess free C₂O₄ 2- The presence of In(C2O4)3 can also make 3- The stable pH range is widened, which on the one hand makes it easier to control the pH of the leaching pulp, and on the other hand, In(C2O4)3 3- The stronger the stability in the leachate, the better; however, the leaching of In2O3 has requirements on the final pH value, that is, the final pH value must be sufficient to leach In2O3 and produce In. 3+ And the leached In 3+ Can react with C2O4 2- Complexation, but because the In2O3 content in waste ITO conductive glass powder is relatively low, theoretically, leaching In2O3 requires (C2O4) 2- ) T The amount is greater than the actual leaching of (C2O4) 2- ) T The demand.

[0079] The method for separating indium and tin described in this invention uses oxalic acid as the leaching agent and reagent A, which are low-risk. (C2O4) 2-It can also be recycled and reused; it has the advantages of simple operation, good separation of indium and tin, low equipment requirements and low environmental pollution. Moreover, the crystal structure and surface morphology of the glass residue after leaching are not significantly changed, and the tin can be recovered and reused as glass raw material in the production of glass substrates.

[0080] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for leaching and separating indium and tin from ITO conductive glass powder, characterized in that, include: ITO conductive glass powder is mixed with a leaching agent solution to obtain a leaching slurry; wherein the leaching agent solution is prepared with oxalic acid, reagent A, reagent B and water; reagent A is oxalate and reagent B is a sulfiding agent; The leaching slurry is stirred and leached. After the leaching reaction is completed, it is filtered and separated to obtain leaching residue and leaching solution. The leachate was subjected to a hydrolysis reaction to precipitate indium. After the reaction was completed, the solution was filtered to obtain indium precipitate filtrate and indium residue. In the leaching slurry, the liquid-to-solid ratio of the leaching agent solution to the ITO conductive glass powder is (6-10) mL / g; The oxalate is one of sodium oxalate, ammonium oxalate, and potassium oxalate; the reagent B is one of sodium sulfide, ammonium sulfide, and TAA. In the leaching agent solution, the molar mass ratio of oxalic acid to oxalate is (2-1):(1-2), and c(C2O4) 2- ) T The molar concentration is 0.10-0.18 mol / L; the amount of reagent B added is 0.02%-0.1% of the weight of the ITO conductive glass powder; When the leaching slurry is stirred and leached, the leaching temperature is 60-90℃ and the stirring and leaching time is 20-60min; The process of hydrolyzing the leachate to precipitate indium and obtaining an indium precipitate solution is as follows: After adding indium hydrolysis precipitating reagent C to the leachate, an indium hydrolysis precipitating reaction is carried out. After the reaction is completed, the solution is filtered to obtain indium precipitating filtrate and indium residue.

2. The method for leaching and separating indium and tin from ITO conductive glass powder according to claim 1, characterized in that, The indium precipitation reagent C is NaOH or NH3. One of H2O and KOH, wherein the endpoint pH of the indium hydrolysis precipitation reaction is 8-11; the indium slag is indium slag containing In(OH)3.

3. The method for leaching and separating indium and tin from ITO conductive glass powder according to claim 1, characterized in that, The indium precipitation filtrate is diverted; a portion of the indium precipitation filtrate is returned to the leaching slurry preparation step for conditioning the leaching slurry; the other portion of the indium precipitation filtrate is used as a raw material for regenerating oxalate.

4. The method for leaching and separating indium and tin from ITO conductive glass powder according to claim 1, characterized in that, In the leaching solution, the leaching rate of indium is 82.68%-97.74%.

5. The method for leaching and separating indium and tin from ITO conductive glass powder according to claim 1, characterized in that, The particle size of the ITO conductive glass powder is less than 0.75 μm.

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