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CN-121516836-B - Production process for preparing electroplating grade potassium pyrophosphate

CN121516836BCN 121516836 BCN121516836 BCN 121516836BCN-121516836-B

Abstract

The invention discloses a production process of electroplating grade potassium pyrophosphate, which takes potassium carbonate and phosphorus pentoxide as raw materials, adds a cocatalyst and reacts in a high-pressure reaction kettle. After the reaction is completed, adding water for dissolution, and controlling the pH value of the slurry to be 9.0-10.0. Filtering by a fine filter, pumping into a slurry storage tank, maintaining the slurry storage tank at 75-95 ℃. And pumping the storage tank slurry into an evaporation concentration device for concentration, pumping the concentrated solution into a continuous crystallization device for continuous crystallization, and recovering filtrate again into the evaporation concentration device after centrifugal treatment. And (3) the potassium pyrophosphate crystal enters vacuum drying equipment to carry out vacuum drying treatment, and then is crushed, sieved and packaged into a finished product. The potassium pyrophosphate crystal obtained by the method has high purity, less caking phenomenon and stable and controllable product quality.

Inventors

  • QU MANYI
  • CHEN YULIANG
  • QU YUN
  • HUANG SHENGCHAO
  • ZHOU JUN
  • WANG DONG

Assignees

  • 湖北兴发化工集团股份有限公司

Dates

Publication Date
20260508
Application Date
20260116

Claims (7)

  1. 1. The preparation method of the electroplating grade potassium pyrophosphate is characterized by comprising the following steps of: S1, mixing potassium carbonate and phosphorus pentoxide in the presence of a cocatalyst, and then performing high-temperature solid-phase reaction in a closed reactor to obtain a reaction product containing potassium pyrophosphate, wherein the cocatalyst is anhydrous potassium citrate, calcium aspartate and lithium cobaltate, and the adding amount of the cocatalyst is 0.01 wt-1.5 wt% based on the total mass of the potassium carbonate and the phosphorus pentoxide; S2, dissolving the reaction product obtained in the step S1 in water, and regulating the pH value of the obtained slurry to be in a range of 9.0-10.0 to obtain refined slurry; S3, evaporating and concentrating the refined slurry obtained in the step S2 to obtain potassium pyrophosphate concentrated solution; s4, crystallizing the potassium pyrophosphate concentrated solution obtained in the step S3 to obtain potassium pyrophosphate crystal slurry; S5, carrying out solid-liquid separation on the potassium pyrophosphate crystal slurry obtained in the step S4 to obtain wet potassium pyrophosphate crystals and mother liquor; S6, drying the wet potassium pyrophosphate crystal obtained in the step S5, wherein the drying is vacuum drying, the drying condition is that the vacuum degree is-0.06 MPa to-0.15 MPa, the temperature is 60 to 120 ℃, and the moisture content of the dried material is controlled to be 2 to 4 percent, so that the electroplating grade potassium pyrophosphate product is obtained.
  2. 2. The method according to claim 1, wherein in step S1, the reaction temperature of the high temperature solid phase reaction is 350 ℃ to 420 ℃ and the reaction time is 1 hour to 6 hours.
  3. 3. The preparation method according to claim 2, wherein the high-temperature solid phase reaction comprises a first reaction stage and a second reaction stage, wherein the reaction temperature of the first reaction stage is 260 ℃ to 320 ℃ and the reaction time is 3 hours to 5 hours, and the reaction temperature of the second reaction stage is 380 ℃ to 400 ℃ and the reaction time is 0.5 hours to 2 hours.
  4. 4. The method according to claim 1, wherein in step S2, after dissolving in water, the pH of the slurry is adjusted by using an alkaline solution or carbon dioxide gas, and after obtaining the refined slurry in step S2 and before evaporating and concentrating in step S3, the method further comprises a step of maintaining the refined slurry at a temperature of 75 ℃ to 95 ℃.
  5. 5. The method according to claim 1, wherein in step S3, the concentration by evaporation is controlled such that the concentration of potassium pyrophosphate in the obtained concentrate is 70 to 85% by mass.
  6. 6. The method according to claim 1, wherein in step S4, the crystallization treatment is continuous cooling crystallization, and the temperature of the crystallization process is controlled to be in the range of 30 ℃ to 50 ℃.
  7. 7. The process according to any one of claims 1 to 6, wherein in step S1, the purity of the potassium carbonate is not less than 99% and the purity of the phosphorus pentoxide is not less than 99%.

Description

Production process for preparing electroplating grade potassium pyrophosphate Technical Field The invention relates to a production process and a device for preparing electroplating grade potassium pyrophosphate, belonging to the technical field of inorganic salts. Background The chemical formula of the potassium pyrophosphate is K 4P2O7, the relative molecular weight is 330.334, the English name is Potassium pyrophosphate, and the potassium pyrophosphate is called tetrapotassium pyrophosphate respectively. White solid powder at room temperature has strong hygroscopicity, is very soluble in water, and is insoluble in organic solvents such as ethanol and glycerol. In the industrial field, the method is mainly used for cyanide-free electroplating, can be used as a substitute of cyanide complexing agent, can obviously reduce environmental pollution, simultaneously reduce toxic and side effects on human bodies, and can obviously improve the quality of a coating. Can also be used as a scale remover, and can obviously reduce the hardness of water and prevent scaling by combining with calcium and magnesium ions. The pigment dye can also be used as a ceramic clay dispersing agent and a pigment dye dispersing agent to improve the stability of the production process and the product quality. In the field of foods, the water-retaining agent is used as an emulsifying agent and a quality improver to prevent the generation of struvite and the discoloration of fruits of canned aquatic products and improve the water-retaining property of meat products and the expansion degree of ice cream. In addition, it is often compounded with phosphate such as sodium pyrophosphate, etc. and is used as a binder for meat products such as ham sausage, etc. The traditional method for synthesizing potassium pyrophosphate generally comprises evaporating and concentrating potassium dihydrogen phosphate solution, cooling and crystallizing to obtain potassium dihydrogen phosphate solid, and calcining at high temperature. The method has more steps, and particularly has the problems of uneven heating of potassium dihydrogen phosphate solid, easy caking during calcination and the like in large calcination equipment, higher energy consumption required by production, unstable product quality, low reaction conversion rate and the like. Disclosure of Invention The invention aims to solve the problems and provide a method for preparing potassium pyrophosphate by utilizing phosphorus pentoxide and potassium carbonate in a high-pressure reaction kettle. The invention provides a method for preparing potassium pyrophosphate by taking potassium carbonate and phosphorus pentoxide as raw materials, which comprises the following steps of (1) mixing the potassium carbonate and the phosphorus pentoxide in the presence of a cocatalyst, and then carrying out high-temperature solid-phase reaction in a closed reactor to obtain a reaction product containing the potassium pyrophosphate. Then the reaction kettle is discharged, and the tail gas is discharged. (2) Adding water into the reaction kettle to completely dissolve the solid powder into a solution, and controlling the pH value of the solution to be 9.0-10.0. Then enters a fine filtering tank for filtering, and filtrate enters a slurry storage tank to maintain the temperature of the slurry storage tank at 75-95 ℃. Then enters an evaporation concentration device to start concentration, and then enters a continuous crystallization device to perform continuous crystallization operation. After centrifugal treatment, the filtrate is returned to the evaporation concentration device, potassium pyrophosphate crystals enter vacuum drying equipment for vacuum drying treatment, and then are crushed, screened and packaged into finished products. In the step (1), the cocatalyst is anhydrous potassium citrate, calcium aspartate and lithium cobaltate. The promoter is added in an amount of 0.01 wt% to 1.5% wt% based on the total mass of the potassium carbonate and phosphorus pentoxide. The purity of the potassium carbonate is more than or equal to 99 percent, and the purity of the phosphorus pentoxide is more than or equal to 99 percent. The reaction temperature of the high-temperature solid-phase reaction is 350-420 ℃ and the reaction time is 1-6 hours. In some preferred cases, the high temperature solid phase reaction comprises a first reaction stage and a second reaction stage, wherein the reaction temperature of the first reaction stage is 260 ℃ to 320 ℃ and the reaction time is 3 hours to 5 hours, and the reaction temperature of the second reaction stage is 380 ℃ to 400 ℃ and the reaction time is 0.5 hours to 2 hours. In the step S2, after adding water for dissolution, alkaline solution or carbon dioxide gas is adopted to adjust the pH value of the slurry, and after the refined slurry is obtained in the step S2 and before the evaporation concentration in the step S3, the method further comprises the step of preserving the he