Method for resource utilization of indium oxide production wastewater

Abstract

The invention relates to a method for resource utilization of indium oxide production wastewater, which comprises the following steps of: filtering the indium oxide production wastewater containing ammonium nitrate by using a chelating resin column to remove indium ions in the wastewater; then feeding the filtered wastewater into low-temperature vacuum evaporation equipment for concentration to obtain a 94-95 wt% ammonium nitrate concentrated solution; and adding calcium carbonate into the ammonium nitrate concentrated solution, mixing, granulating, cooling to room temperature, and screening to obtain calcium ammonium nitrate. According to the method, indium ions can be recycled by backwashing the chelating resin column, the resource utilization rate is increased, meanwhile, the calcium ammonium nitrate compound fertilizer is obtained and can be used as a fertilizer to supplement the requirement of crops on calcium, waste is turned into wealth, and zero emission of wastewater in indium oxide production is completely achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a method for recycling the wastewater generated in the production process of indium oxide. Background Art

[0002] Indium oxide has excellent optical and electrical properties and is widely used in fields such as flat panel displays, solar cells, sensors, and photocatalysis. The chemical precipitation method has low requirements for equipment and can obtain powders with high purity and good uniformity. It is currently the main method for industrial production of indium oxide. However, this method will generate a large amount of high-concentration ammonia-containing wastewater, and the wastewater contains a large amount of ammonium nitrate.

[0003] Ammonium nitrate is a weakly explosive oxidant and nitrogen fertilizer, and is the basic raw material for the production of military energetic materials, civilian explosives, and agricultural fertilizers. Pure ammonium nitrate is relatively stable at room temperature and is not sensitive to impact, collision, or friction. However, with the increase in temperature and the action of certain impurities, its physical and chemical properties will be affected or changed, and even lead to the instability or explosion of the system. Ammonium nitrate is relatively safe when it contains more than 3% water, but it will still decompose at a certain temperature. Safety regulations must be strictly observed during production, storage, transportation, and use.

[0004] The existing technologies for treating ammonia-containing wastewater generally adopt high-temperature evaporation, electrodialysis combined with evaporation treatment processes, or mixing with a large amount of other wastewater for dilution and then treatment processes, etc. In addition to the disadvantages of high energy consumption and high operating costs, they also have certain risks. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for recycling indium oxide production wastewater to solve the problems of high energy consumption, high operating costs, and risks of the existing wastewater treatment processes.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A method for recycling indium oxide production wastewater, comprising the following steps: (1) Filtering the indium oxide production wastewater containing ammonium nitrate through a chelating resin column to remove indium ions in the wastewater; (2) Feeding the filtered wastewater into a low-temperature vacuum evaporation device for concentration to obtain a 94-95 wt% ammonium nitrate concentrate; (3) Adding calcium carbonate to the ammonium nitrate concentrate, mixing and granulating, cooling to room temperature after granulation, and then screening to obtain calcium ammonium nitrate.

[0007] Further, the chelating resin in step (1) is one of phosphoric acid-based chelating resin, carboxylic acid-based chelating resin, and pyridine-based chelating resin.

[0008] Further, the phosphoric acid chelating resin is one of D412, D418, and MC-95; the carboxylic acid chelating resin is one of Chelex-100, Amberlite IRC-50, and Muromac A-1; the pyridine chelating resin is one of 2-APR, 3-APR, and 4-APR.

[0009] Further, the conditions for low-temperature vacuum evaporation in step (2) are: evaporation temperature 30 - 60°C, vacuum degree -80 to -100 KPa.

[0010] Further, the mass ratio of the ammonium nitrate concentrate to calcium carbonate in step (3) is 7.4 - 8.2:1.8 - 2.6.

[0011] The method of the present invention has the following beneficial effects: 1. Using a chelating resin column to filter indium in wastewater, indium ions can be recovered by backwashing the chelating resin column, improving the resource utilization rate.

[0012] 2. Concentrating ammonium nitrate by means of low-temperature vacuum evaporation, with an evaporation temperature of only 30 - 60°C, not only reduces energy consumption, but also improves the safety of operation. Moreover, the low-temperature vacuum evaporation equipment is not prone to scale formation, has good water output continuity, and low equipment maintenance costs.

[0013] 3. Adding a stabilizer calcium carbonate to the ammonium nitrate concentrate to form calcium ammonium nitrate, which not only has the characteristics of low hygroscopicity, not easily decomposing, and not caking, but also significantly increases the thermal stability of ammonium nitrate, reduces the fire or explosion hazards during storage and transportation, and has high safety.

[0014] 4. Adding calcium to ammonium nitrate to form a calcium ammonium nitrate compound fertilizer, which can be used as a fertilizer to supplement the calcium requirement of crops, neutralize soil acidity, turn waste into treasure, and at the same time completely achieve zero discharge of indium oxide production wastewater. Specific Embodiments

[0015] The content of the present invention will be described in detail below in conjunction with embodiments, but the protection scope of the present invention is not limited to the described content.

[0016] All the operation methods mentioned in the embodiments are conventional methods in the art unless otherwise specified. The materials, equipment, and instruments used in the following embodiments can be obtained commercially unless otherwise specified. Example 1

[0017] A method for the resource utilization of indium oxide production wastewater, the method steps are as follows: (1) Pump the indium oxide production wastewater containing ammonium nitrate into a chelating resin column and filter it using a D412-type resin column. Removing indium ions from wastewater(The indium concentration in the wastewater can be determined by atomic absorption spectrometry.)

[0018] (2) Feed the filtered wastewater into Low-temperature vacuum evaporation equipment for concentration. The evaporation temperature is 40 °C and the vacuum degree is -93 KPa to obtain an ammonium nitrate concentrated solution with a concentration of 94 wt%. The H-2T low-temperature vacuum evaporator purchased from the market is used in this example. Low-temperature vacuum evaporation and concentration can reduce energy consumption and risks.)

[0019] (3) Introduce the ammonium nitrate concentrated solution into the mixing tank, and add calcium carbonate to the ammonium nitrate concentrated solution as a stabilizer, which can prevent the decomposition of ammonium nitrate and increase the thermal stability of ammonium nitrate. The mass ratio of the ammonium nitrate concentrated solution to calcium carbonate is 7.4:2.6. After the ammonium nitrate concentrated solution and calcium carbonate are mixed evenly, they are sent to a granulator for granulation. After granulation, it is cooled to room temperature and then screened to obtain calcium ammonium nitrate with a particle size of 1-4 mm. After detection, no indium ions are detected.) Example 2

[0020] A method for recycling the wastewater from indium oxide production, the method steps are as follows: (1) Pump the indium oxide production wastewater containing ammonium nitrate into a chelating resin column, and use a Chelex-100 resin column for filtration to remove indium ions in the wastewater.)

[0021] (2) Feed the filtered wastewater into a low-temperature vacuum evaporation device for concentration. The evaporation temperature is 30 °C and the vacuum degree is -100 KPa to obtain an ammonium nitrate concentrated solution with a concentration of 95 wt%.)

[0022] (3) Introduce the ammonium nitrate concentrated solution into the mixing tank, and add calcium carbonate to the ammonium nitrate concentrated solution. The mass ratio of the ammonium nitrate concentrated solution to calcium carbonate is 8:2. After the ammonium nitrate concentrated solution and calcium carbonate are mixed evenly, they are sent to a granulator for granulation. After granulation, it is cooled to room temperature and then screened to obtain calcium ammonium nitrate with a particle size of 1-4 mm. After detection, no indium ions are detected.) Example 3

[0023] A method for recycling the wastewater from indium oxide production, the method steps are as follows: (1) Pump the indium oxide production wastewater containing ammonium nitrate into a chelating resin column, and use a 4-APR resin column for filtration to remove indium ions in the wastewater.)

[0024] (2) Feed the filtered wastewater into a low-temperature vacuum evaporation device for concentration. The evaporation temperature is 60 °C and the vacuum degree is -80 KPa to obtain an ammonium nitrate concentrated solution with a concentration of about 94.5 wt%.)

[0025] (3) Introduce the ammonium nitrate concentrate into a mixing tank, and add calcium carbonate to the ammonium nitrate concentrate. The mass ratio of the ammonium nitrate concentrate to calcium carbonate is 8.2:2.6. After the ammonium nitrate concentrate and calcium carbonate are mixed evenly, they are sent to a granulator for granulation. After granulation, it is cooled to room temperature and then screened to obtain calcium ammonium nitrate with a particle size of 1-4 mm. After testing, indium ions are not detected. Example 4

[0026] A method for resource utilization of indium oxide production wastewater, the method steps are as follows: (1) Pump the indium oxide production wastewater containing ammonium nitrate into a chelating resin column, and use a D412 type resin column for filtration to remove indium ions in the wastewater.

[0027] (2) Send the filtered wastewater into a low-temperature vacuum evaporation device for concentration. The evaporation temperature is 50 °C and the vacuum degree is -85 KPa to obtain an ammonium nitrate concentrate with a concentration of about 95 wt%.

[0028] (3) Introduce the ammonium nitrate concentrate into a mixing tank, and add calcium carbonate to the ammonium nitrate concentrate. The mass ratio of the ammonium nitrate concentrate to calcium carbonate is 7.4:1.8. After the ammonium nitrate concentrate and calcium carbonate are mixed evenly, they are sent to a granulator for granulation. After granulation, it is cooled to room temperature and then screened to obtain calcium ammonium nitrate with a particle size of 1-4 mm. After testing, indium ions are not detected.

[0029] The above embodiments are only partial embodiments of the present invention, not all embodiments. The above embodiments do not limit the protection scope of the present invention. Furthermore, those skilled in the art should understand that when filtering the indium oxide production wastewater containing ammonium nitrate with a chelating resin column, the chelating resin can be one of phosphoric acid chelating resins, carboxylic acid chelating resins, and pyridine chelating resins. The phosphoric acid chelating resins include but are not limited to any one of D412, D418, and MC-95. The carboxylic acid chelating resins include but are not limited to any one of Chelex-100, Amberlite IRC-50, and Muromac A-1. The pyridine chelating resins include but are not limited to any one of 2-APR, 3-APR, and 4-APR.

Claims

1. A method for resource utilization of indium oxide production wastewater, characterized in that: The following steps are involved: (1) Filter the indium oxide production wastewater containing ammonium nitrate using a chelating resin column to remove indium ions from the wastewater; (2) sending the filtered wastewater to a low-temperature vacuum evaporation device for concentration to obtain a 94-95wt% ammonium nitrate concentrate; (3) Add calcium carbonate to the ammonium nitrate concentrate, mix and granulate, cool to room temperature after granulation, and then sieve to obtain calcium ammonium nitrate.

2. A method for resource utilization of indium oxide production wastewater according to claim 1, characterized in that: The chelating resin in step (1) is one of a phosphoric acid chelating resin, a carboxylic acid chelating resin and a pyridine chelating resin.

3. A method for resource utilization of indium oxide production wastewater according to claim 2, characterized in that: The phosphate chelating resin is one of D412, D418 and MC-95; the carboxylic acid chelating resin is one of Chelex-100, AmberliteIRC-50 and Muromac A-1; and the pyridine chelating resin is one of 2-APR, 3-APR and 4-APR.

4. A method for resource utilization of indium oxide production wastewater according to claim 1 or 2, characterized in that: The conditions of low-temperature vacuum evaporation in step (2) are: evaporation temperature 30-60°C, vacuum degree -80 to -100 KPa.

5. A method for resource utilization of indium oxide production wastewater according to claim 1 or 2, characterized in that: The mass ratio of the ammonium nitrate concentrate to calcium carbonate in step (3) is 7.4-8.2:1.8-2.6.