Method for recycling APT (ammonium paratungstate) production wastewater

Abstract

The invention discloses an APT production wastewater recycling method, and relates to the field of APT production wastewater circulation, and the APT production wastewater recycling method comprises the following steps: pulping and refining a pulpified liquid, and preparing tungsten trioxide containing more than 80% of tungsten, a causticized liquid, a silicon inhibitor and a refiner; tungsten trioxide and the causticized liquid are put into a pulping tank according to the ratio of liquid to solid being 4: 1, and the particle size of tungsten trioxide is 180-200 meshes; adding a silicon inhibitor, stirring for 30 minutes, and uniformly slurrying to obtain slurrying liquid; the prepared pulpified liquid is subjected to refining treatment through an ultrasonic processor, the ultrasonic power is 300 W, and the treatment time is 15 minutes; and adding a refiner, and continuously stirring for 10 minutes to further refine the granularity of the slurrying liquid. According to the method disclosed by the invention, the cyclic utilization rate of the wastewater and the resource recovery efficiency are remarkably improved by optimizing the ingredients and the process of each working procedure and particularly improving the key steps of causticization, pulping, alkaline leaching, extraction and the like.

Description

Technical Field

[0001] This invention relates to the field of APT production wastewater recycling, and in particular to a method for recycling APT production wastewater. Background Technology

[0002] Ammonium paratungstate (APT) is an important intermediate product in the tungsten industry, widely used in the manufacture of tungsten powder, tungsten wire, and tungsten alloys. Traditional APT production methods mainly include chemical methods, ion exchange methods, and solvent extraction methods. Among these, solvent extraction is widely used due to its advantages such as high efficiency and environmental friendliness. However, existing solvent extraction methods still have some problems in the production process, which limit their further development and application.

[0003] In the traditional APT production process, a large amount of wastewater is discharged, mainly consisting of high-concentration sodium tungstate solution and raffinate. If this wastewater is discharged directly without treatment, it will cause serious environmental pollution. In the traditional APT production process, the causticization process requires steam heating, which consumes a lot of energy and has a low lime utilization rate. In addition, the high cost of wastewater treatment and resource recycling further increases the production cost.

[0004] Therefore, it is necessary to propose a method for recycling APT production wastewater to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for recycling APT production wastewater. By optimizing the ingredients and processes of each step, especially by improving key steps such as causticization, pulping, alkali leaching and extraction, the recycling rate and resource recovery efficiency of the wastewater are significantly improved.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for recycling APT production wastewater, comprising:

[0007] S1: Causticization. Collect the raffinate from the APT production wastewater, transport the raffinate to the causticization pulping tank, add metered lime to carry out the causticization reaction, let the causticized slurry stand in the causticization pulping tank for 1 to 2 days, and then filter it to obtain the causticized liquid.

[0008] S2: Pulping and refining of pulping solution, preparing tungsten trioxide containing more than 80% tungsten, causticized solution, silicon inhibitor, and refining agent;

[0009] Tungsten trioxide and causticized liquid are added to the slurry tank at a liquid:solid ratio of 4:1, with the tungsten trioxide particle size being 180-200 mesh.

[0010] Add the silicon inhibitor, stir for 30 minutes to homogenize the slurry, and obtain the slurry solution;

[0011] The prepared slurry was refined by an ultrasonic processor with an ultrasonic power of 300W and a processing time of 15 minutes.

[0012] Add a finer agent and continue stirring for 10 minutes to further refine the particle size of the slurry.

[0013] S3: Alkali leaching. The slurry is put into the alkali leaching kettle, the steam pressure is controlled at 0.1-0.4 MPa, the temperature is raised to 90℃, and the temperature is maintained for half an hour. Then, gas-liquid separation is carried out. The liquid is discharged into the thick slurry tank through the gas-liquid separation device, and compressed air is injected into the thick slurry tank to cool the thick slurry. Then, pressure filtration is carried out. When the temperature of the thick slurry drops to 70℃, pressure filtration is carried out. The filtrate after pressure filtration is adjusted with causticized liquid or raffinate to adjust the tungsten trioxide concentration and pH value to maintain it at 110-120 g / L and pH=10-14.

[0014] Finally, a precision filtration process is performed on the filtrate after pressure filtration. The filtered fine filtrate then enters the extraction process.

[0015] S4: Input the fine filtrate into the extraction tank, add the extractant for extraction, add the causticized liquid during extraction to adjust the pH value, so that the pH of the raffinate is adjusted to 10-14, and the generated raffinate enters the raffinate circulation tank.

[0016] The extractant after the reaction in the extraction tank is sent to the clarification tank for clarification, and the clarified liquid is sent to the back-extraction tank.

[0017] A stripping agent is added to the stripping tank for stripping to obtain a stripping solution with a tungsten trioxide concentration of 180–200 g / L.

[0018] Finally, the extractant after back-extraction is recycled back into the extraction tank, and the raffinate is recycled into the causticizing process.

[0019] S5: Tungsten recovery and ammonia recovery, prepare ammonium sulfide: 1 / 30 of the volume of the back-extraction liquid, back-extraction liquid and concentrated sulfuric acid;

[0020] The back-extraction solution is passed through an activated carbon column to remove oil. The oil-removed liquid is then fed into a sulfidation unit, where ammonium sulfide is added. After stirring evenly, the mixture is allowed to stand to obtain a sulfidated back-extraction solution.

[0021] The sulfide back-extraction solution is added to the molybdenum removal device for molybdenum removal. The molybdenum-removed liquid enters the preparation solution storage tank to form the molybdenum-removed liquid.

[0022] After the preparation solution is filtered through a precision filter, it is de-oiled by an activated carbon column and then tungsten is recovered by an ion exchange column. The resulting tungsten-containing peak solution is then mixed evenly with the solution in the alkaline leaching process.

[0023] The ammonia and water vapor released during the evaporation and crystallization in the crystallization kettle are recovered and used to make ammonia water, which is then used to prepare the back-extraction agent and enter the extraction process.

[0024] S6: Crystallization and wastewater treatment. The molybdenum-removed liquid is added to the crystallization kettle for crystallization reaction. The steam pressure is controlled at 0-0.4 MPa during crystallization, and the crystallization endpoint is controlled at 1.03-1.01 MPa.

[0025] After crystallization, the crystalline solution is separated into liquid and crystals. The mother liquor from the primary crystallization is pumped into the secondary crystallization kettle by a liquid pump for recrystallization.

[0026] The tail liquid produced by desorption and regeneration of resin is discharged into the wastewater tank and evaporated through a triple-effect evaporator. During evaporation, the vapor pressure is controlled at 0.1 to 0.2 MPa and the vacuum degree is controlled at -0.03 to -0.08 MPa to complete the wastewater treatment.

[0027] Preferably, in S2, the silicon inhibitor is 1 / 15 to 1 / 20 of the weight of tungsten trioxide; and the refining agent is 1 / 30 to 1 / 40 of the weight of tungsten trioxide.

[0028] Preferably, the refining agent in S2 is polyethylene glycol and sodium dodecyl sulfate.

[0029] Preferably, the extractant in S4 consists of tributyl phosphate, kerosene, and isooctyl alcohol.

[0030] Preferably, the stripping agent in S4 is a sodium carbonate solution.

[0031] The technical effects and advantages of this invention are as follows:

[0032] 1. By optimizing processes such as causticizing, pulping, alkali leaching, and extraction, the recovery rates of tungsten and molybdenum in the tailings have been significantly improved. The recovery rate of tungsten has increased from 80% in the traditional process to over 95%, and the recovery rate of molybdenum has increased from 70% to over 90%, reducing resource waste and increasing economic benefits.

[0033] 2. By recycling a portion of the tail liquid into the pulping process and treating the other portion through evaporation, zero wastewater discharge is achieved. The condensate after evaporation can be recycled for the preparation of back-extraction agents, further improving the utilization rate of water resources, reducing production costs, and meeting environmental protection requirements.

[0034] 3. By adopting static treatment instead of steam heating, the lime utilization rate has increased from 60% in the traditional process to over 80%, significantly reducing steam consumption and lime usage, and lowering production costs;

[0035] 4. By refining the particle size distribution of the slurry and optimizing the alkaline leaching and extraction conditions, the quality stability of APT products has been significantly improved; the produced APT products can consistently meet the national Class 0 standard, thus enhancing the market competitiveness of the products.

[0036] 5. The use of ultrasonic treatment to refine the slurry, rapid gas-liquid separation, and efficient extraction technology significantly shortens the processing time of each process; the processing time of the alkali leaching process is reduced from 2 hours in the traditional process to 1 hour, and the processing time of the extraction process is reduced from 1.5 hours to 1 hour, thus improving production efficiency. Attached Figure Description

[0037] Figure 1 This is a flow chart of the causticization process in the APT production wastewater recycling method of the present invention.

[0038] Figure 2 This is a flow chart of pulping and refining process in the APT production wastewater recycling method of the present invention.

[0039] Figure 3 This is a flowchart of the alkaline leaching process in the APT production wastewater recycling method of the present invention.

[0040] Figure 4 This is a flowchart of the extraction process in the APT production wastewater recycling method of the present invention. Detailed Implementation

[0041] This invention provides, for example Figures 1-4 The method for recycling APT production wastewater shown includes:

[0042] The first step is to collect the raffinate from the APT production wastewater and transfer it to a causticizing pulping tank. Measured lime is added to carry out the causticizing reaction, and the pH value in the causticizing pulping tank is controlled at 10-14. The causticized slurry after the reaction is allowed to stand in the causticizing pulping tank for 1-2 days, and then filtered to obtain the causticized liquid. The filtrate after filtration (causticized liquid) is used for subsequent pulping processes.

[0043] The second step is pulping and refining the pulp solution:

[0044] First, the ingredients are prepared, including: tungsten trioxide (WO3) containing more than 80% tungsten, causticized liquid, silicon inhibitor: 1 / 15 to 1 / 20 of the weight of tungsten trioxide, and finer agent: 1 / 30 to 1 / 40 of the weight of tungsten trioxide, used to refine the particle size of the slurry.

[0045] The pulping process includes: adding tungsten trioxide and causticized liquid into a pulping tank at a liquid:solid ratio of 4:1, with the tungsten trioxide particle size being 180-200 mesh; adding a silicon inhibitor and stirring for 30 minutes to homogenize the pulp and obtain a pulped liquid.

[0046] The process of refining the slurry includes: refining the prepared slurry through an ultrasonic processor with an ultrasonic power of 300W for 15 minutes; adding a refining agent (polyethylene glycol and sodium dodecyl sulfate) and continuing to stir for 10 minutes to further refine the particle size of the slurry and ensure uniform particle size distribution.

[0047] Step 3, alkaline soaking:

[0048] The slurry is poured into an alkaline leaching kettle, the steam pressure is controlled at 0.1-0.4 MPa, the temperature is raised to 90°C, and the temperature is maintained for half an hour.

[0049] Then, gas-liquid separation is performed. The liquid is discharged into the thickening tank through the gas-liquid separation device, and compressed air is injected into the thickening tank to cool the thickening slurry.

[0050] Then, pressure filtration is performed. When the temperature of the concentrated slurry drops to 70°C, pressure filtration is performed. The filtrate after pressure filtration is adjusted with causticized liquid or raffinate to maintain the tungsten trioxide concentration and pH value at 110-120 g / L and pH = 10-14.

[0051] Finally, a precision filtration process is performed on the filtrate after pressure filtration. The filtered fine filtrate then enters the extraction process.

[0052] The fourth step includes: extraction, clarification, back-extraction, and recycling.

[0053] The extraction process involves feeding the finely filtered liquid into an extraction tank, adding an extractant (composed of tributyl phosphate, kerosene, and isooctanol) for extraction, and adding causticized liquid to adjust the pH value during extraction so that the pH of the raffinate is adjusted to 10-14. The resulting raffinate then enters the raffinate circulation tank.

[0054] Clarification involves clarifying the extractant from the extraction tank by transferring it to a clarification tank, and then transferring the clarified liquid to a back-extraction tank.

[0055] The back-extraction process involves adding a back-extraction agent (sodium carbonate solution) to a back-extraction tank to obtain a back-extraction solution with a tungsten trioxide concentration of 180–200 g / L.

[0056] Finally, the extractant after back-extraction is recycled back into the extraction tank, and the raffinate is recycled into the causticizing process.

[0057] Step 5: Tungsten and ammonia recovery:

[0058] Prepare ammonium sulfide: 1 / 30 of the volume of the back-extraction solution, the back-extraction solution, and concentrated sulfuric acid (for the molybdenum precipitation reaction).

[0059] The tungsten recovery and ammonia recovery processes include the following steps:

[0060] 1. Deoiling and Sulfurization: The back-extraction liquid is deoiled by passing it through an activated carbon column. The deoiled liquid enters the sulfurization device, ammonium sulfide is added, and after stirring evenly, it is allowed to stand to obtain the sulfurized back-extraction liquid.

[0061] 2. Molybdenum removal: The sulfide back-extraction solution is added to the molybdenum removal device for molybdenum removal. The molybdenum-removed liquid enters the mixing solution storage tank to form the molybdenum-removed liquid.

[0062] 3. Tungsten recovery: After the preparation solution is precisely filtered, it is degreased by an activated carbon column and then passed through an ion exchange column for tungsten recovery. The resulting tungsten-containing peak solution is mixed evenly with the material solution in the alkaline leaching process.

[0063] 4. Ammonia recovery: The ammonia gas and water vapor released during the evaporation and crystallization in the crystallization kettle are recovered and used to make ammonia water, which is then used to prepare the back-extraction agent and enter the extraction process.

[0064] Step 6, crystallization and wastewater treatment:

[0065] 1. Crystallization: The molybdenum-removed liquid is added to a crystallization vessel for crystallization reaction. The steam pressure is controlled at 0-0.4 MPa during crystallization, and the crystallization endpoint is controlled at 1.03-1.01.

[0066] 2. Liquid-crystal separation: After crystallization, the liquid and crystals of the crystalline solution are separated. The mother liquor from the primary crystallization is pumped into the secondary crystallization kettle by a pump for recrystallization.

[0067] 3. Wastewater treatment: The tail liquid generated from desorption and regeneration of resin is discharged into the wastewater tank and evaporated through a triple-effect evaporator. During evaporation, the vapor pressure is controlled at 0.1 to 0.2 MPa and the vacuum degree is controlled at -0.03 to -0.08 MPa.

Claims

1. A method for recycling APT production wastewater, characterized in that, include: S1: Causticization. Collect the raffinate from the APT production wastewater, transport the raffinate to the causticization pulping tank, add metered lime to carry out the causticization reaction, let the causticized slurry stand in the causticization pulping tank for 1 to 2 days, and then filter it to obtain the causticized liquid. S2: Pulping and refining of pulping solution, preparing tungsten trioxide containing more than 80% tungsten, causticized solution, silicon inhibitor, and refining agent; Tungsten trioxide and causticized liquid are added to the slurry tank at a liquid:solid ratio of 4:1, with the tungsten trioxide particle size being 180-200 mesh. Add the silicon inhibitor, stir for 30 minutes to homogenize the slurry, and obtain the slurry solution; The prepared slurry was refined by an ultrasonic processor with an ultrasonic power of 300W and a processing time of 15 minutes. Add a finer agent and continue stirring for 10 minutes to further refine the particle size of the slurry. S3: Alkali leaching. The slurry is put into the alkali leaching kettle, the steam pressure is controlled at 0.1-0.4 MPa, the temperature is raised to 90℃, and the temperature is maintained for half an hour. Then, gas-liquid separation is carried out. The liquid is discharged into the thick slurry tank through the gas-liquid separation device, and compressed air is injected into the thick slurry tank to cool the thick slurry. Then, pressure filtration is carried out. When the temperature of the thick slurry drops to 70℃, pressure filtration is carried out. The filtrate after pressure filtration is adjusted with causticized liquid or raffinate to adjust the tungsten trioxide concentration and pH value to maintain it at 110-120 g / L and pH=10-14. Finally, a precision filtration process is performed on the filtrate after pressure filtration. The filtered fine filtrate then enters the extraction process. S4: Input the fine filtrate into the extraction tank, add the extractant for extraction, add the causticized liquid during extraction to adjust the pH value, so that the pH of the raffinate is adjusted to 10-14, and the generated raffinate enters the raffinate circulation tank. The extractant after the reaction in the extraction tank is sent to the clarification tank for clarification, and the clarified liquid is sent to the back-extraction tank. A stripping agent is added to the stripping tank for stripping to obtain a stripping solution with a tungsten trioxide concentration of 180–200 g / L. Finally, the extractant after back-extraction is recycled back into the extraction tank, and the raffinate is recycled into the causticizing process. S5: Tungsten recovery and ammonia recovery, prepare ammonium sulfide: 1 / 30 of the volume of the back-extraction liquid, back-extraction liquid and concentrated sulfuric acid; The back-extraction solution is passed through an activated carbon column to remove oil. The oil-removed liquid is then fed into a sulfidation unit, where ammonium sulfide is added. After stirring evenly, the mixture is allowed to stand to obtain a sulfidated back-extraction solution. The sulfide back-extraction solution is added to the molybdenum removal device for molybdenum removal. The molybdenum-removed liquid enters the preparation solution storage tank to form the molybdenum-removed liquid. After the preparation solution is filtered through a precision filter, it is de-oiled by an activated carbon column and then tungsten is recovered by an ion exchange column. The resulting tungsten-containing peak solution is then mixed evenly with the solution in the alkaline leaching process. The ammonia and water vapor released during the evaporation and crystallization in the crystallization kettle are recovered and used to make ammonia water, which is then used to prepare the back-extraction agent and enter the extraction process. S6: Crystallization and wastewater treatment. The molybdenum-removed liquid is added to the crystallization kettle for crystallization reaction. The steam pressure is controlled at 0-0.4 MPa during crystallization, and the crystallization endpoint is controlled at 1.03-1.01 MPa. After crystallization, the crystalline solution is separated into liquid and crystals. The mother liquor from the primary crystallization is pumped into the secondary crystallization kettle by a liquid pump for recrystallization. The tail liquid produced by desorption and regeneration of resin is discharged into the wastewater tank and evaporated through a triple-effect evaporator. During evaporation, the vapor pressure is controlled at 0.1 to 0.2 MPa and the vacuum degree is controlled at -0.03 to -0.08 MPa to complete the wastewater treatment.

2. The method for recycling APT production wastewater according to claim 1, characterized in that: In S2, the silicon inhibitor is 1 / 15 to 1 / 20 of the weight of tungsten trioxide; the refining agent is 1 / 30 to 1 / 40 of the weight of tungsten trioxide.

3. The method for recycling APT production wastewater according to claim 1, characterized in that: The refining agents in S2 are polyethylene glycol and sodium dodecyl sulfate.

4. The method for recycling APT production wastewater according to claim 1, characterized in that: The extractant in S4 consists of tributyl phosphate, kerosene, and isooctyl alcohol.

5. The method for recycling APT production wastewater according to claim 1, characterized in that: The stripping agent in S4 is a sodium carbonate solution.

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