phosphoric acid production plant

Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula H₃PO₄. It is commonly encountered as an 85% aqueous solution, which is a colorless, odorless, and non-volatile syrupy liquid.

Phosphoric acid is an important chemical with a wide range of applications. It is most commonly used in the following industries:

• Agriculture: The dominant use of phosphoric acid is for fertilizers (DAP, MAP, SPA, TSP, etc.…), providing essential phosphorus for plant growth.
• Food and beverage: Phosphoric acid is used as an acidulant in food and beverages, and it also acts as a preservative and flavor enhancer.
• Pharmaceuticals: Phosphoric acid is used in the manufacture of a variety of pharmaceuticals, including vitamins, minerals, and antacids.
• Metallurgy: Phosphoric acid is used in the metalworking industry to remove rust and scale from metal surfaces.
• New energy: Lithium iron phosphate (LFP) battery is one of the mainstream power batteries for new energy vehicles at present, and phosphoric acid is a key raw material for the production of cathode materials. With the development of new energy, the demand for phosphoric acid and phosphates is increasing rapidly.
• Other applications: Phosphoric acid is also used in a variety of other applications, including water treatment, detergent manufacturing, and flame retardants.

The commercial methods used to produce phosphoric acid (H₃PO₄) include wet process, thermal process, and dry kiln process. Wet process is the most implemented technology for phosphoric acid production.

In the wet process, a phosphate-containing mineral such as calcium hydroxyapatite and fluorapatite are treated with sulfuric acid. Calcium sulfate (gypsum, CaSO4) is a by-product, which is removed as phosphogypsum. The hydrogen fluoride (HF) gas is streamed into a wet (water) scrubber producing hydrofluoric acid. Select suitable operating conditions, the calcium sulfate will be precipitated in dihydrate or hemihydrate form. Currently, for more than 85% wet process phosphate acid device, the calcium sulfate precipitated in dihydrate form and the crude phosphoric acid solution usually contains 23–33% P₂O₅ (32–46% H₃PO₄). It can be concentrated to produce commercial grade phosphoric acid, which contains about 54–62% P₂O₅ (75–85% H₃PO₄). Further purified by removing of compounds of arsenic and other potentially toxic impurities, it can be used to produce industrial-grade and food-grade phosphate acid.