I.Introduction
Trisodium phosphate is a very versatile chemical. It has a variety of production processes due to various factors such as raw materials, control of reaction conditions, market demand and technological progress.
Trisodium phosphate production methods mainly include spray drying method, hot phosphoric acid method, extraction of phosphoric acid method, neutralization method, and gypsum method.
II.Manufacturing methods
A. Spray drying method
Raw material: trisodium phosphate dodecahydrate crystals
Production steps:
- Add raw materials and water to the dissolving tank, heating and stirring to dissolve the raw materials
- Purification solution
- Pump the purified solution to the metering tank
- Atomization, spray drying
- Produce anhydrous trisodium phosphate finished product.
B. Hot phosphoric acid method
Raw materials: hot phosphoric acid and caustic soda
Production steps:
- Neutralization reaction
- Crystallization by cooling
- Centrifugation
- Drying to obtain product
C. Extraction of phosphoric acid method
Raw materials: industrial soda ash, phosphate ore, sulfuric acid, liquid caustic soda
Production steps:
- Phosphate ore powder reacts with sulfuric acid to get extracted phosphoric acid.
- Neutralize the extracted phosphoric acid with industrial soda ash at 90~100℃.
- Filtration,
- Neutralization.
- Add trisodium phosphate mother liquor
- Add liquid caustic soda, adjust the sodium storage ratio, and
- Cooling crystallization
- Centrifugal separation, air drying, trisodium phosphate dodecahydrate finished product.
D. Neutralization method
Raw materials: food-grade phosphoric acid and food-grade caustic soda
Production steps:
- Dilute phosphoric acid with non-ionized water, add to the reactor with stirring, and
- Add food grade caustic soda solution for neutralization reaction.
- Add purifying agent
- Filter the impurities.
- The filtrate is cooled and crystallized.
- Centrifugal separation, drying, food grade trisodium phosphate dodecahydrate finished product.
This method is usually used for food grade trisodium phosphate producing.
E. Gypsum method
Raw materials: apatite ore and gypsum
Production steps:
- Pre-treatment of raw materials
- Mixing, calcination
- Water leaching
- Filtration, crystallization
- Washing, drying, sieving, to produce industrial grade trisodium phosphate
III.Conclusion
The above is the production process of trisodium phosphate. Generally speaking, chemical factories will choose different process methods according to the application and other factors (such as cost, environmental protection, etc.). Therefore, when buying trisodium phosphate, you need to be clear about the application or figure out the required indexes, so as to buy a satisfactory product.
