Method for leaching and separating indium and tin in ITO conductive glass powder

Abstract

The invention relates to the technical field of ITO (indium tin oxide) 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 the ITO conductive glass powder with a leaching agent solution to obtain leaching ore pulp; wherein the leaching agent solution is prepared from oxalic acid, a reagent A, a reagent B and water; the reagent A is oxalate, and the reagent B is one of sodium sulfide, ammonium sulfide and TAA; stirring and leaching the leached ore pulp, and filtering and separating after the leaching reaction is finished, so as to obtain leached residues and leached liquid; carrying out hydrolysis indium precipitation reaction on the leachate, and filtering after the reaction is finished to obtain indium precipitation filtrate and indium slag; the method has the advantages of being good in leaching selectivity, high in indium leaching speed, high in leaching rate and low in energy consumption in the leaching process, and the indium leaching rate of the method is far higher than that of traditional oxalic acid leaching.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization of urban solid electronic waste, and in particular relates to a method for leaching and separating indium and tin in ITO conductive glass powder. Background Art

[0002] ITO (Indium Tin Oxides) is composed of indium oxide and tin oxide, with a mass ratio of 9:1. It is an excellent transparent conductive material widely used in electronic displays, solar cells, LEDs and other fields. With the rapid development of electronic information technology, the consumption of ITO targets, the raw materials for producing indium tin oxide films, has increased significantly, while the natural resources of indium are limited. Therefore, under the dual background of increasing demand for indium and increasing waste of ITO conductive glass, waste ITO targets after magnetron sputtering coating and waste ITO conductive glass have become the main raw materials for regenerating indium. The recovery of indium from waste ITO targets and waste ITO conductive glass is of great significance for alleviating the contradiction between supply and demand of indium resources, reducing production costs and reducing environmental pollution. The effective recovery of indium from waste ITO palladium and waste ITO conductive glass has become an important link in the ITO industry chain.

[0003] At present, the methods for recovering indium from ITO waste palladium and waste ITO conductive glass mainly include dry method and wet method; among them, the dry method includes high-temperature pyrolysis, high-temperature reduction and chlorination volatilization, and the high-temperature reduction method includes atmospheric pressure carbon thermal reduction, vacuum carbon thermal reduction and hydrogen reduction; the wet method mainly includes inorganic acid method and oxalic acid method.

[0004] Specifically, although the high-temperature pyrolysis method has a low processing temperature, the decomposition product is an indium-tin alloy, and vacuum distillation or wet electrolysis is required to further separate indium and tin; although the vacuum carbon thermal reduction temperature is lower than the atmospheric carbon thermal reduction temperature, the vacuum reduction has high requirements for equipment; although the hydrogen reduction method has no carbon emission problem, it also has the problems of high energy consumption and low reduction efficiency. Although the reduction method has the advantages of short process and simple operation process, the final product of the reduction is an indium-tin alloy, and the separation effect of indium and tin in the reduction process is relatively poor, and vacuum distillation or wet electrolysis is required to further separate indium and tin in the alloy; although the chlorination volatilization method has the advantages of high indium recovery rate, short chlorination volatilization time, and lower chlorination temperature than the thermal reduction method, the chlorination process will produce highly corrosive and toxic Cl-containing tail gas, and a Cl-containing tail gas treatment system must be set up, and there are also disadvantages of complex process flow, high chlorination reaction temperature and high energy consumption.

[0005] When using wet leaching to separate indium and tin, the leaching agents are mainly hydrochloric acid, sulfuric acid, nitric acid and inorganic mixed acid; among them, the inorganic acid method has the advantages of short leaching time, low energy consumption and no harmful smoke; but this method has low leaching pH, poor separation effect of indium and tin, and strong corrosiveness; in addition, the application process of nitric acid and hydrochloric acid is easy to volatilize, and the working conditions are also poor; although oxalic acid has the advantages of short leaching time, high indium leaching rate, and higher separation effect of indium and tin than carbon thermal reduction method and inorganic acid method for ITO waste palladium. However, when oxalic acid is used to leach and separate indium and tin from waste ITO glass powder, because it contains a high content of quartz, a solid film will be formed during the leaching process, resulting in a low leaching rate of indium, and the separation effect of indium and tin needs to be further improved. Therefore, it is urgent 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] In view of the defects of the prior art, the present invention provides a method for leaching and separating indium and tin in ITO conductive glass powder, so as to solve the problem that when separating indium and tin in ITO conductive glass powder by leaching with oxalic acid, the indium leaching rate is low and the separation effect of indium and tin is poor due to the low leaching pH.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a method for leaching and separating indium and tin in ITO conductive glass powder, comprising: The ITO conductive glass powder is mixed with a leaching agent solution to obtain a leached 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 a sulfiding agent; Stirring and leaching the leached slurry, filtering and separating after the leaching reaction is completed to obtain leached residue and leaching liquid; The leachate is subjected to a hydrolysis indium precipitation reaction, and after the reaction is completed, it is filtered to obtain an indium precipitation filtrate and indium slag.

[0008] Furthermore, in the leached slurry, the liquid-to-solid ratio of the leaching agent solution to the ITO conductive glass powder is (6-10) mL / g.

[0009] 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.

[0010] Furthermore, in the leaching agent solution, the molar mass ratio of the oxalic acid to the oxalate is (2-1): (1-2), and c(C2O4 2- ) TThe molar concentration is 0.10-0.18 mol / L; the added amount of the reagent B is 0.02%-0.1% of the weight of the ITO conductive glass powder.

[0011] Furthermore, when the leaching slurry is subjected to stirring leaching, the leaching temperature is 60-90° C. and the stirring leaching time is 20-60 min.

[0012] Further, the leachate is hydrolyzed to precipitate indium to obtain an indium precipitation solution, which is specifically as follows: After adding the hydrolysis indium precipitation reagent C to the leachate, a hydrolysis indium precipitation reaction is carried out, and after the reaction is completed, the reaction is filtered to obtain an indium precipitation filtrate and an indium slag.

[0013] Furthermore, the hydrolysis indium precipitation reagent C is one of NaOH, NH3∙H2O and KOH, and the end point pH of the hydrolysis indium precipitation reaction is 8-11; the indium slag is indium slag containing In(OH)3.

[0014] Furthermore, the indium precipitation filtrate is subjected to a diversion treatment; wherein a portion of the indium precipitation filtrate is returned to the step of preparing the leaching slurry for use in the slurry adjustment process of the leaching slurry; and another portion of the indium precipitation filtrate is used as a raw material for regenerating oxalate.

[0015] Furthermore, in the leaching solution, the leaching rate of indium is 82.68%-97.74%.

[0016] Furthermore, the particle size of the ITO conductive glass powder is less than 0.75 μm.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The invention provides a method for leaching and separating indium and tin in ITO conductive glass powder. The mixed solution of oxalic acid, reagent A and reagent B is used as a leaching agent solution to leach indium in the waste ITO conductive glass, while leaving tin in the leaching residue to achieve the separation of indium and tin. In the separation process, by adding reagent A and reagent B, it is ensured that indium is rapidly leached by complexation at a higher pH, while suppressing the leaching of tin. The method has the advantages of fast indium leaching speed, high indium leaching rate and good indium and tin separation effect, and the indium leaching rate is higher than the indium leaching rate when oxalic acid leaches the waste ITO conductive glass powder. The addition of reagent B can not only suppress the leaching of tin, but also reduce and suppress the leaching of iron, thereby achieving the purpose of purifying the leachate and improving the purity of In(OH)3 obtained by hydrolyzing and precipitating indium; in addition, oxalic acid and reagent A are environmentally friendly reagents, and both are solid, so they are convenient to keep, store and transport.

[0018] 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, the change in water volume had little effect on the pH value of the leaching slurry, ensuring that In2O3 in the waste ITO conductive glass powder could be leached by oxalic acid to obtain In 3+ , leached In 3+ Then with C2O4 2- Complexation is carried out to improve the leaching rate of indium.

[0019] Furthermore, in the leaching agent solution, the molar ratio of oxalic acid to reagent A is controlled to be (2-1): (1-2), and c(C2O4 2- ) T The molar concentration of In is controlled at 0.10-0.50 mol / L to ensure 3+ In the leaching solution, In(C2O4)3 with a large cumulative stability constant should be formed as much as possible. 3- , while excess free C2O4 2- The presence of In(C2O4)3 3- The stable pH range is widened, which is convenient for controlling the pH value of the leaching process and enhancing the 3- The stability in the leaching solution improves the leaching rate of indium. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is an electron microscope photo of the ITO glass powder in Example 1; Figure 2 This is an electron microscope photograph of the leached slag in Example 1. DETAILED DESCRIPTION

[0022] In order 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 described clearly and completely in combination with the drawings in the embodiments of this application; obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The present invention provides a method for leaching and separating indium and tin in ITO conductive glass powder, comprising the following steps: Step 1: Add water, oxalic acid, reagent A and reagent B into a leaching tank, stir and dissolve, and obtain a leaching agent solution; wherein the reagent A is oxalate, the molar mass ratio of the oxalic acid to the 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 added amount of the reagent B is 0.02%-0.1% of the weight of the ITO conductive glass powder.

[0025] Step 2, stirring the leaching agent solution, and adding ITO conductive glass powder during the stirring process to obtain a leached slurry; wherein, in the leached 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.

[0026] Step 3, stirring and leaching the leached slurry, filtering and separating after the leaching process is completed to obtain leached residue and leaching liquid; wherein, during the stirring leaching, the leaching temperature is 60-90° C., and the stirring leaching time is 20-60 min.

[0027] Step 4: adding a hydrolysis indium precipitation reagent to the leachate to carry out a hydrolysis indium precipitation reaction, filtering after the reaction is completed to obtain an indium precipitation filtrate and an indium slag; wherein the hydrolysis indium precipitation reagent C is one of NaOH, NH3∙H2O and KOH, and the pH during the hydrolysis indium precipitation reaction is 8-11; the indium slag is an indium slag containing In(OH)3.

[0028] Step 5, diverting the indium precipitation filtrate; wherein a portion of the indium precipitation filtrate is returned to the process of preparing the leaching slurry in step 2 for slurry adjustment of the leaching slurry; and another portion of the indium precipitation filtrate is used as a raw material for regenerating the reagent A.

[0029] Separation principle of indium and tin: The method for leaching and separating indium and tin in ITO conductive glass of the present invention comprises the following steps: mixing oxalic acid, reagent A and reagent B to obtain a leaching agent solution; mixing the leaching agent solution with waste ITO conductive glass powder to obtain a leaching slurry; and stirring and leaching the leaching slurry to achieve selective leaching of indium in the ITO conductive glass and separation of indium and tin; wherein, during the stirring and leaching reaction, C2O4 2- In 3+ It has strong complexation to generate In(C2O4)3 with large cumulative stability constant 3- , complex 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 both are solid, which is convenient to keep, store and transport.

[0030] Specifically, the leaching agent solution is a mixed reagent prepared by oxalic acid, reagent A and reagent B. Reagent A in the mixed reagent plays two roles in the leaching process: one is to provide complexing In 3+ C2O4 2- ; The second is to adjust the pH value of the leaching system; because In 3+ With C2O4 2- Can form In(C2O4) with different accumulation stability constants + 、In(C2O4)2 - and In(C2O4)3 3- ; Among them, In(C2O4)3 3- The cumulative stability constant of In is the largest; 3+ The specific form of indium oxalate complex in the leachate depends on the pH value at the leaching end point and c(C2O4 2- ) T concentration; In the present 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 of In is controlled at 0.10-0.18 mol / L, ensuring that the leached In 3+ Convert to In(C2O4)3 with large cumulative stability constant as much as possible 3- , effectively improving the leaching rate of indium and shortening the leaching time of indium.

[0031] In the present invention, the process of leaching In2O3 in ITO conductive glass by using a mixed reagent prepared by oxalic acid, reagent A and reagent B, namely, strengthening the coordination leaching of In2O3, while inhibiting the acid leaching of soluble metal tin and α-SnO2, and at the same time, the addition of reagent B further increases the leached Sn 2+The conversion into SnS2 precipitation and reduction inhibits the leaching of iron, leaving the tin in the leaching residue, which is beneficial to the recovery of tin in the leaching residue and improving the recovery rate of tin. The glass residue after tin recovery can be further reused.

[0032] Example 1 This embodiment 1 provides a method for leaching and separating indium and tin in ITO conductive glass powder, comprising the following steps: Step 1: Add water, oxalic acid, sodium oxalate and sodium sulfide into a leaching tank, stir and 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 is 0.10 mol / L, and the amount of sodium sulfide added is 0.02% of the weight of the ITO glass powder.

[0033] Step 2: Add 10 g of ITO conductive glass powder to 100 mL of the leaching agent solution and stir to obtain a leached slurry; wherein the electron microscope photo of the ITO conductive glass powder is as shown in the attached figure. Figure 1 shown.

[0034] Step 3, stirring and leaching the leached slurry at 90°C for 60 minutes, filtering after the leaching reaction to obtain leached residue and leaching liquid; wherein the electron microscope photo of the leached residue is as shown in the attached Figure 2 shown.

[0035] Step 4, adding a 50% by mass NaOH solution to the leachate to perform a hydrolysis indium precipitation reaction, and obtaining an indium precipitation solution after the reaction is completed; wherein the pH during the hydrolysis indium precipitation reaction is 8.

[0036] 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.

[0037] Step 6, diverting the indium precipitation filtrate; wherein a portion of the indium precipitation filtrate is returned to the step of preparing the leaching slurry for use in the slurry adjustment process of the leaching slurry; and another portion of the indium precipitation filtrate is used as a raw material for regenerating sodium oxalate.

[0038] Result test description: The contents of indium and tin in the ITO conductive glass powder were detected, and the contents of indium and tin in the mixed solution were detected, wherein the mixed solution was a combined solution of the leaching solution and the 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.

[0039] Example 2 The method for leaching and separating indium and tin from ITO conductive glass powder provided in this embodiment 2 is basically the same as the steps and principles of the method for leaching and separating indium and tin from ITO conductive glass powder described in the above embodiment 1, except that: In step 1, sodium oxalate is replaced by ammonium oxalate, the molar ratio of oxalic acid to the ammonium oxalate is 2:1, and sodium sulfide is replaced by ammonium sulfide; in step 4, a 30% NH3∙H2O solution is added to the leachate, and the pH of the leachate is adjusted to 10 to perform a hydrolysis precipitation reaction of indium, and an indium precipitation solution is obtained after the reaction is completed; the remaining steps are basically the same and will not be repeated here.

[0040] Result test description: In Example 2, when the molar ratio of oxalic acid to ammonium oxalate is 2:1, a 100 mL volume of 0.10 mol / L c(C2O4 2- ) T and 0.05% ammonium sulfide solution containing the weight of ITO glass powder. After leaching 10g of waste ITO conductive glass at 90℃ for 60min, the leaching rates of indium and tin were 92.68% and 0.47% respectively.

[0041] Example 3 The method for leaching and separating indium and tin from ITO conductive glass powder provided in this embodiment 3 is basically the same as the steps and principles of the method for leaching and separating indium and tin from ITO conductive glass powder described in the above embodiment 1, except that: In step 1, sodium oxalate is replaced with potassium oxalate, the molar ratio of oxalic acid to the potassium oxalate is 1:2, and sodium sulfide is replaced with TAA; in step 4, a KOH solution with a mass fraction of 50% is added to the leachate, and the pH of the leachate is adjusted to 8.5 to perform a hydrolysis precipitation reaction of indium, and an indium precipitation solution is obtained after the reaction is completed; the remaining steps are basically the same and will not be repeated here.

[0042] Result test description: In Example 3, when the molar ratio of oxalic acid to potassium oxalate is 1:2, a 100 mL volume of 0.10 mol / L c(C2O4 2- ) T and TAA containing 0.10% of the weight of ITO glass powder. After leaching 10g of waste ITO glass at 90℃ for 60min, the leaching rates of indium and tin were 91.41% and 0.11%, respectively.

[0043] Example 4 The method for leaching and separating indium and tin from ITO conductive glass powder provided in this embodiment 4 is basically the same as the steps and principles of the indium leaching method for ITO conductive glass described in the above embodiment 1, except that: In step 1, the c(C2O4 2- ) T The molar concentration is 0.18 mol / L, and sodium sulfide is replaced by TAA; in step 3, the leached slurry is stirred and leached at 70°C; in step 4, a KOH solution with a mass fraction of 50% is added to the leachate, and the pH of the leachate is adjusted to 8.5 to perform a hydrolysis 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 repeated here.

[0044] Result test description: In Example 4, when the molar ratio of oxalic acid to potassium oxalate is 1:2, a 100 mL volume of 0.18 mol / L c(C2O4 2- ) T And TAA solution containing 0.10% of the weight of ITO glass powder, after leaching 10g of waste ITO glass at 70℃ for 60min, the leaching rates of indium and tin were 92.35% and 0.16%, respectively.

[0045] Example 5 The steps and principle of the method for leaching and separating indium and tin from ITO conductive glass powder provided in this embodiment 5 are basically the same as those of the leaching method for leaching and separating indium and tin from ITO conductive glass described in the above embodiment 1, except that: 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 leached slurry is 6 mL / g; in step 4, a 50% mass fraction NaOH solution is added to the leachate, and the pH of the leachate is adjusted to 9 to perform a hydrolysis 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 repeated here.

[0046] Result test description: 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 and contains 0.18 mol / L of c(C2O4 2- ) T and sodium sulfide containing 0.03% of the weight of ITO glass powder. After leaching 10g of waste ITO glass at 90℃ for 60min, the leaching rates of indium and tin were 95.18% and 0.18% respectively.

[0047] Example 6 The method for leaching and separating indium and tin from ITO conductive glass powder provided in this embodiment 6 is basically the same as the steps and principles of the method for leaching and separating indium and tin from ITO conductive glass described in the above embodiment 1, except that: 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 leached slurry is 10 mL / g; in step 3, the stirring leaching time is 20 min; in step 4, a sodium sulfide solution with a mass fraction of 50% is added to the leachate, and the pH of the leachate is adjusted to 10 to perform a hydrolysis 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 repeated here.

[0048] Result test description: 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 of c(C2O4 2- ) T and sodium sulfide containing 0.08% of the weight of ITO glass powder. After leaching 10g of waste ITO glass at 90°C for 20min, the leaching rates of indium were 95.07%, and tin was not leached.

[0049] The invention discloses a method for leaching and separating indium and tin in ITO conductive glass powder. The method comprises the following steps: preparing a leaching agent solution using oxalic acid, a reagent A, a reagent B and water, leaching In2O3 in the ITO conductive glass using the leaching agent solution, suppressing the leaching of tin and iron, separating the leached slurry to obtain a leaching solution and a leaching residue; and obtaining indium residue and a reagent A solution by hydrolyzing the leaching solution to precipitate indium and separating the leaching solution. The method has the characteristics of fast indium leaching speed, high indium leaching rate, good indium and tin separation effect, low energy consumption in the leaching and separation process, simple leaching equipment, low environmental pollution and easy industrialization.

[0050] In the present invention, the leaching agent solution is a mixed reagent prepared by oxalic acid, reagent A, reagent B and water, and the oxalic acid in the mixed reagent is used to leach In2O3 in the ITO conductive glass powder to produce In 3+ , using reagent A to increase the leaching pH, using C2O4 2- In 3+ It has a strong complexing effect, making the leached In 3+ Transformed into In(C2O4)3 with large accumulation stability constant 3- , strengthen the complex leaching of indium, and the increase of leaching pH can also inhibit the leaching of tin; the addition of reagent B can make the leached Sn 2+It is precipitated and enriched in the leaching residue in the form of SnS precipitation, which improves the separation effect of indium and tin and is also beneficial to improving the recovery rate of tin in the leaching residue.

[0051] In the present invention, the liquid-to-solid ratio of the leaching agent solution to the ITO conductive glass powder is controlled at 6-10 mL / g. In this liquid-to-solid ratio range, the change in the liquid volume has little effect on the pH value of the leached slurry. The pH value of the leached slurry is mainly achieved by adjusting the molar ratio of oxalic acid and reagent A. Specifically, for In2O3 in the ITO conductive glass, the In2O3 produced by leaching is 3+ In(C2O4)3 is completely formed in the leaching solution 3- , then n(C2O4 2- ) T / n(In 3+ ) T Molar ratio ≥3:1, n(C2O4 2- ) molar number is larger, that is, the c(C2O4 2- ) T The higher the concentration, the greater the driving force of the In2O3 leaching process, and the better the indium leaching effect; and the excess free C2O4 2- The presence of In(C2O4)3 3- The stable pH range is widened, which can conveniently control the pH value of the leaching slurry, and on the other hand, In(C2O4)3 3- The stronger the stability in the leaching solution, the better the leaching performance. However, the leaching of In2O3 has requirements for the pH value at the leaching end point, that is, the pH value at the leaching end point must be sufficient to leach In2O3 and produce In 3+ , and the leached In 3+ Can react with C2O4 2- However, due to the relatively low content of In2O3 in the waste ITO conductive glass powder, the theoretical leaching of In2O3 requires (C2O4 2- ) T The amount is greater than the actual leaching of (C2O4 2- ) T demand.

[0052] The method for separating indium and tin of the present invention uses oxalic acid and reagent A, which are less dangerous, and C2O4 2- It can also be recycled and reused; it has the advantages of simple operation process, good separation effect of indium and tin, low equipment requirements, and little environmental pollution. The lattice structure and surface morphology of the glass residue after leaching do not change significantly. After the tin in it is recovered, it can be reused as glass raw material in the production of glass substrates.

[0053] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A method for leaching and separating indium and tin from ITO conductive glass powder, characterized in that: include: The ITO conductive glass powder is mixed with a leaching agent solution to obtain a leached 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 a sulfiding agent; Stirring and leaching the leached slurry, filtering and separating after the leaching reaction is completed to obtain leached residue and leaching liquid; The leachate is subjected to a hydrolysis indium precipitation reaction, and after the reaction is completed, it is filtered to obtain an indium precipitation filtrate and indium slag.

2. A method for leaching and separating indium and tin in ITO conductive glass powder according to claim 1, characterized in that: 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.

3. A method for leaching and separating indium and tin in ITO conductive glass powder according to claim 1, characterized in that: The oxalate is one of sodium oxalate, ammonium oxalate and potassium oxalate; the reagent B is one of sodium sulfide, ammonium sulfide and TAA.

4. A method for leaching and separating indium and tin in ITO conductive glass powder according to claim 1, characterized in that: In the leaching agent solution, the molar mass ratio of the oxalic acid to the oxalate is (2-1): (1-2), and c(C2O4 2- ) T The molar concentration is 0.10-0.18 mol / L; the added amount of the reagent B is 0.02%-0.1% of the weight of the ITO conductive glass powder.

5. The method for leaching and separating indium and tin in ITO conductive glass powder according to claim 1, characterized in that: When the leaching pulp is subjected to stirring leaching, the leaching temperature is 60-90° C. and the stirring leaching time is 20-60 min.

6. The method for leaching and separating indium and tin in ITO conductive glass powder according to claim 1, characterized in that: The process of hydrolyzing the leachate to precipitate indium to obtain an indium precipitation solution is as follows: After adding the hydrolysis indium precipitation reagent C to the leachate, a hydrolysis indium precipitation reaction is carried out, and after the reaction is completed, the reaction is filtered to obtain an indium precipitation filtrate and an indium slag.

7. The method for leaching and separating indium and tin in ITO conductive glass powder according to claim 1, characterized in that: The hydrolysis indium precipitation reagent C is one of NaOH, NH3∙H2O and KOH, and the end point pH of the hydrolysis indium precipitation reaction is 8-11; the indium slag is indium slag containing In(OH)3.

8. The method for leaching and separating indium and tin in ITO conductive glass powder according to claim 1, characterized in that: The indium precipitation filtrate is subjected to a diversion treatment; wherein a portion of the indium precipitation filtrate is returned to the step of preparing the leaching slurry for use in the slurry adjustment process of the leaching slurry; and another portion of the indium precipitation filtrate is used as a raw material for regenerating oxalate.

9. The method for leaching and separating indium and tin in 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%.

10. The method for leaching and separating indium and tin in 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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