Method for recovering and preparing indium oxide from electronic industry ITO (Indium Tin Oxide) wastewater

Abstract

The invention relates to a method for recovering nano indium oxide from electronic industry ITO (Indium Tin Oxide) wastewater, which comprises the following steps: firstly, carrying out adsorption treatment on the wastewater through a resin adsorption column, carrying out on-column ion exchange on the wastewater through the adsorption column, and taking out resin saturated by adsorption; drying the resin subjected to adsorption saturation, and crushing and grinding after drying; and finally, calcining the ground resin to obtain an indium oxide product. The method disclosed by the invention can be used for effectively treating the ITO wastewater in the electronic industry, is simple in process, high in preparation yield, low in cost, environment-friendly and safe, can be suitable for mass production, and has a good industrial application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of indium oxide recovery and preparation, and particularly relates to a method for recovering and preparing indium oxide from electronic industrial wastewater. Background Art

[0002] Indium is a strategic rare metal with important industrial application value. It can be made into various compounds and used in fields such as semiconductor materials, electro-optical materials, new functional materials, and special alloys, providing key basic materials for new energy technologies, modern communications, and the semiconductor industry. In recent years, due to the rapid development of the integrated circuit and solar photovoltaic industries, the demand for indium has also increased. In particular, nano-indium oxide has excellent properties in gas sensors, photocatalysis, electrocatalysis, etc. For the above application properties, the smaller the particle size of indium oxide, the smaller its surface area, and more active sites can be exposed, which is beneficial to the improvement of performance.

[0003] Indium is produced as a by-product of zinc and copper, mainly sourced from sphalerite, and a small amount from copper sulfide minerals. Due to being an associated mineral, indium production is restricted by the output of zinc and copper. At the same time, the mining of zinc and copper is always accompanied by environmental pollution, not to mention that China is a country lacking copper. Therefore, the recycling of indium secondary resources has attracted wide attention. Existing treatment methods mainly include hydrometallurgy and pyrometallurgy. For example, Patent CN115261930A uses an ITO waste target as the cathode and graphite as the anode, and direct current electrolysis is carried out in a chloride molten salt to obtain an indium-tin alloy. Then, the indium-tin alloy is used as the anode and molten salt electrolysis is used again for separation to recover metallic indium. Patent CN115449851A electrolyzes the etching waste liquid through an electrolytic cell with an anion exchange membrane, and the indium-rich solution obtained at the anode is evaporated and crystallized to recover and prepare indium sulfate. Patent CN115323176A uses nitric acid leaching - extraction resin adsorption column adsorption - separation column separation to obtain an indium-rich solution. Patent CN112746185A uses the method of mixed vanadate precipitation to remove impurities such as gallium, tin, lead, and iron in the solution in one step, and then directly recovers indium in the solution through a displacement reaction. The advantages of pyrometallurgical treatment are simple operation, low cost, and high efficiency, but the disadvantages are that it cannot recover indium-containing materials with low concentration or complex composition, and may cause secondary pollution. The advantages of hydrometallurgical treatment are that it can recover indium-containing materials with high purity or high proportion, but the disadvantages are complex operation, high cost, low efficiency, and the need to use a large amount of chemical reagents or electric energy. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for recovering and preparing nano-indium oxide from electronic industrial wastewater.

[0005] The solution adopted by the present invention to solve the above technical problems is:

[0006] A method for recovering and preparing indium oxide from ITO wastewater in the electronics industry, comprising the following steps:

[0007] (1) Adjust the pH of the ITO wastewater in the electronics industry so that the pH value is 1-3, for example, pH is 1, pH is 2, pH is 3;

[0008] (2) Use an adsorption column to perform ion exchange adsorption on the obtained ITO wastewater in the electronics industry. The adsorption column is filled with ion exchange resin;

[0009] (3) Dry, crush, and grind the ion exchange resin adsorbed with indium ions;

[0010] (4) Calcinate the crushed resin to obtain nano indium oxide solid powder.

[0011] Preferably, when adjusting the pH in step (1) using an alkaline solution, the alkaline solution is a NaOH solution or a NaCO3 solution.

[0012] Preferably, the ion exchange resin is a cation exchange resin or a chelating resin.

[0013] Preferably, the ion exchange resin is a strong acid cation exchange resin or a weak acid cation exchange resin.

[0014] Preferably, the ion exchange resin is a macroporous styrene-based chelating amino carboxyl ion exchange resin.

[0015] Preferably, in step (2), the flow rate of the electronics industry wastewater through the adsorption column is 0.1-10 mm / min, more preferably 0.5-5 mm / min.

[0016] Preferably, the adsorption temperature in step (2) is 20-80 °C, more preferably 30-40 °C.

[0017] Preferably, the particle size of the resin obtained after grinding in step (3) is 200-500 mesh, more preferably 200-300 mesh.

[0018] Preferably, the calcination temperature in step (4) is 400-900 °C, more preferably 400-600 °C.

[0019] Preferably, the atmosphere for calcination in step (4) is an oxygen-containing gas, such as air or pure oxygen.

[0020] Preferably, the ITO wastewater in the electronics industry contains indium ions and impurity ions; the impurity ions are any one or more of tin, aluminum, zinc, and cadmium.

[0021] This application can controllably prepare nanoscale indium oxide based on the methods of hydrometallurgy and high-temperature calcination. The specific principle is to selectively extract indium from electronic industrial wastewater through ion exchange resin. Most of the impurities in general indium-containing electronic industrial wastewater are tin, aluminum, zinc, cadmium, etc. By adjusting the pH of the wastewater and conditions such as the type of ion exchange resin, the flow rate of the adsorption column, and the temperature of the adsorption column, the effect of selectively adsorbing indium ions can be achieved. Crushing and grinding are to prevent the agglomeration and sintering of indium oxide during subsequent calcination. The crystal growth of indium oxide can be controlled during the calcination process by controlling the sintering atmosphere, temperature, and time.

[0022] The present invention uses ion exchange resin to selectively extract indium, and then regulates the calcination conditions to optimize the preparation of indium oxide, thereby realizing the recovery and preparation of nanoscale indium oxide. Its beneficial effects include:

[0023] (1) This method has a simple process, high operability, and good industrial application prospects.

[0024] (2) This method effectively improves the recovery rate of indium by using ion exchange resin, and can also effectively reduce the grain size during calcination.

[0025] (3) This method using resin adsorption and calcination can be applied to large-scale industrial production, and effectively treats electronic industrial wastewater, killing two birds with one stone. Description of the Drawings

[0026] Figure 1 It is the X-ray diffraction pattern of indium oxide samples prepared in Examples 1-6 and Comparative Example 1;

[0027] Figure 2 It is the grain size of indium oxide samples prepared in Examples 1-6 and Comparative Example 1;

[0028] Figure 3 It is the transmission electron microscope image of the indium oxide sample prepared in Example 1. Detailed Description of the Invention

[0029] The specific embodiments of the present invention will be described in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0030] In the following implementation cases of the present invention, the electronic industrial wastewater used comes from ITO etching waste liquid, which is strongly acidic (pH < 1), in which the concentration of indium is about 1000 ppm, the concentration of tin is about 120 ppm, the concentration of cadmium is about 100 ppm, the concentration of aluminum is about 40 ppm, and the concentration of zinc is about 40 ppm.

[0031] The calculation method of the recovery rate of indium oxide in this application is as follows

[0032] η = 2*m1*n0 / c0*v0*n1

[0033] Where c0 is the concentration of indium in the wastewater flowing through the adsorption column during the experiment, v0 is the volume of the wastewater flowing through the adsorption column during the experiment, m1 is the mass of the product obtained by the adsorption-calcination method, n0 is the relative molecular mass of metallic indium, and n1 is the relative molecular mass of indium oxide.

[0034] The adsorption column packing material used in the following examples is the D401 macroporous styrene-based chelating amino-carboxyl ion exchange resin from Zhengzhou Hecheng New Materials Co., Ltd. The diameter of the adsorption column is 8 mm and the length is 15 mm.

[0035] Example 1

[0036] A method for recovering and preparing indium oxide from ITO wastewater in the electronics industry, the method comprising the following steps:

[0037] Step 1, perform ion exchange on the ITO wastewater in the electronics industry through a resin adsorption column, adjust the pH of the solution to 2 with 1M NaOH solution, the temperature is room temperature, the flow rate of the adsorption column is 2 mm / min, and after adsorption, take out the resin adsorbed with indium ions;

[0038] Step 2, dry the adsorbed resin at 80 °C, and then crush and grind it to 200 mesh;

[0039] Step 3, calcine the crushed resin at 500 °C for 5 hours to obtain nano indium oxide solid powder;

[0040] It is measured that the recovery rate of the nano indium oxide recovered through this process is 92.6%.

[0041] Comparative Example 1

[0042] Adjust the pH of the ITO wastewater solution in the electronics industry to 7 with 1M NaOH solution, a large amount of white flocculent precipitate appears in the solution, and the white precipitate and the solution are separated by a centrifuge. The precipitate is dried, and then ground and crushed into powder. The powder is calcined at 500 °C for 5 hours to obtain nano indium oxide solid powder.

[0043] It is measured that the recovery rate of the nano indium oxide recovered through this process is 37%, and the grain size is 42 nm.

[0044] Examples 2 - 6

[0045] The method is the same as that of Example 1, the difference is that: the calcination temperatures in step (1) are: 900 °C, 800 °C, 700 °C, 600 °C, 400 °C respectively.

[0046] The nanometer indium oxide is recovered through the above technological process, and the recovery rates are 90.3%, 81.4%, 85.9%, 85.5%, and 83.8% respectively.

[0047] Examples 7 - 11

[0048] The method is the same as that of Example 1, with the difference that in step (1), the flow rates of the adsorption column are 1 mm / min, 5 mm / min, 8 mm / min, 10 mm / min, and 15 mm / min respectively.

[0049] The nanometer indium oxide is recovered through this technological process, and the recovery rates are 93.6%, 89.5%, 83.7%, 80.3%, and 67.2% respectively.

[0050] Examples 12 - 15

[0051] The method is the same as that of Example 1, with the difference that in Example 12, the pH value of the ITO wastewater in the electronics industry is not adjusted in step (1), and in Examples 13 - 15, the pH values of the solution are adjusted to 1, 3, and 5 respectively with 1M NaOH solution.

[0052] The nanometer indium oxide is recovered through this technological process, and the recovery rates are 49.6%, 89.2%, 83.7%, and 54.3% respectively.

[0053] Figure 1 It is the X-ray diffraction pattern of the indium oxide samples prepared by the method of this example under different temperature conditions. It can be seen that indium oxide is obtained after calcination at different temperatures. The Scherrer formula is used to analyze the grain size of the XRD pattern, as shown in Figure 2 , and a higher temperature will make the indium oxide crystal coarser. According to the Ostwald ripening mechanism, during the crystal growth process, smaller crystals have a larger curvature, higher energy, and higher solubility, so they will dissolve in the surrounding larger crystal particles, making the larger crystal particles increase and the smaller crystal particles decrease or even disappear.

[0054] Such as Figure 2As shown, the grain size prepared by the traditional precipitation-calcination method is relatively large, exceeding 40 nm, while the grain size can be greatly reduced by the adsorption-calcination method. The grain size of the sample calcined at 400 °C is only 22 nm. This is because, under the action of the organic resin, during the calcination process, the problems of agglomeration and ripening are improved. This is because during the calcination process, the organic resin can spatially disperse the crystal particles over a larger range, making the ripening and growth processes more difficult. The sample obtained by the adsorption-calcination method in Example 1 was tested by TEM, further confirming that the crystal size is between 20-25 nm. In addition, the recovery rate of the sample using the adsorption-calcination method in this application is as high as over 90%, while the recovery rate of the precipitation-calcination method is less than 40%.

[0055] The above is the preferred implementation manner of the present invention. Of course, it cannot be used to limit the scope of the rights of the present invention. It should be pointed out that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and changes can still be made, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A method for recycling and preparing indium oxide from ITO wastewater in the electronic industry, characterized in that, It includes the following steps: (1) Adjust the pH value of the electronic industry ITO wastewater to 1-3; (2) Use an adsorption column to carry out ion exchange adsorption on the obtained electronic industry ITO wastewater, and the adsorption column is filled with ion exchange resin; (3) Dry, crush, and grind the ion exchange resin adsorbed with indium ions; (4) Calcinate the crushed resin to obtain nano indium oxide solid powder.

2. The method for recycling indium oxide from ITO wastewater in the electronics industry according to claim 1, wherein When adjusting the pH with an alkaline solution in step (1), the alkaline solution is selected from NaOH solution or Na2CO3 solution.

3. The method for recycling and preparing indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, The ion exchange resin is a cation exchange resin or a chelating resin.

4. The method for recycling and preparing indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, The ion exchange resin is a macroporous styrene-based chelating amino carboxyl ion exchange resin.

5. The method for recycling indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, In step (2), the flow rate of the electronic industry wastewater flowing through the adsorption column is 1-10 mm / min.

6. The method for recovering and preparing indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, The adsorption temperature in step (2) is 20-80 °C.

7. The method for recycling and preparing indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, The particle size of the resin obtained after grinding in step (3) is 200-500 mesh.

8. The method for recovering and preparing indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, The calcination temperature in step (4) is 400-900 °C.

9. The method for recovering and preparing indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, The atmosphere for calcination in step (4) is an oxygen-containing gas or pure oxygen.

10. The method for recovering and preparing indium oxide from ITO wastewater in the electronic industry according to claim 1, characterized in that, The electronic industry ITO wastewater contains indium ions and impurity ions; the impurity ions include any one or more of tin, aluminum, zinc, and cadmium.

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