Industrial phosphoric acid pure products are colorless, transparent, viscous liquid or orthorhombic crystal, odorless and sour in taste. The commercially available phosphoric acid content is mostly 85%, which is colorless, transparent or slightly light-colored and thick liquid. Mainly used in electroplating industry, pharmaceutical industry, phosphate industry and metallurgical industry. Phosphoric acid vapor has a strong corrosive effect on the skin, and the staff should pay attention to protect the respiratory organs and skin.
Physical and chemical properties of pure product is colorless transparent viscous liquid or orthorhombic crystal, odorless, taste very acid. The 85% phosphoric acid sold in the market is a colorless, transparent or slightly light-colored, thick liquid. Melting point 42.35 ℃. At a boiling point of 213°C (loss of H2O), pyrophosphoric acid is produced. Heating to 300°C becomes metaphosphoric acid. Relative density d181.834. Soluble in water, soluble in ethanol. Its acidity is weaker than strong acids such as sulfuric acid, hydrochloric acid and nitric acid, but stronger than weak acids such as acetic acid and boric acid. Can stimulate the skin together inflammation, damage the body tissue. Concentrated phosphoric acid has an erosive effect when heated in porcelain. Hygroscopic.
Wet-process phosphoric acid is mainly used to manufacture various phosphates, such as ammonium phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, and condensed phosphates. Refined phosphoric acid is used to make calcium hydrogen phosphate for feed. Used for metal surface phosphating treatment, preparation of electrolytic polishing liquid and chemical polishing liquid for polishing aluminum products. The pharmaceutical industry is used in the manufacture of oil sodium phosphate, iron phosphate, etc., and also in the manufacture of zinc phosphate as a dental filling adhesive. Used as a catalyst for the condensation of phenolic resin, a desiccant for the production of fuels and intermediates. The printing industry is used to prepare a cleaning solution for wiping off stains on offset printing plates. Also used in the preparation of matchstick stains. Metallurgical industry for the production of phosphoric acid refractory mud, improve steel furnace life. It is the coagulant of rubber slurry and the raw material of inorganic binder. The paint industry is used as a metal antirust paint.