Sulfuric Acid → Phosphoric Acid

Participants

Reaction Conditions

Reaction Steps

Concentrated sulfuric acid containing 93% by weight of H2SO4 was continuously pumped to a mixing tee. Also continuously added to the mixing tee was gypsum pond water containing about 0.9% by weight of P2O5, about 0.2% by weight of CaO (2,000 ppm), and about 0.4% H2SO4 and having a pH of about 2.3. Sufficient amounts of gypsum pond water were added to the concentrated acid to produce a diluted acid having about 72% by weight of H2SO4. The diluted acid at a temperature of about 265° F was then cooled in a shell-and-tube heat exchanger through which cooling water flowed on the shell side. The diluted acid, at an exit temperature of about 140° F, was fed directly to a digestion tank containing ground phosphate rock to produce wet phosphoric acid and by-product calcium sulfate hemihydrate. The process was operated for five days, during which the following data was obtained periodically:

Provenance & Evidence