Ammonia → Calcium Carbonate

Participants

Reaction Steps

U.S. Pat. No. 2,753,252, Barnes, July 3, 1956, it is proposed that a substantially completely citrate soluble phosphatic product may be prepared by reacting phosphate rock with nitric acid, filtering the gangue, evaporating free water from the acidulate by boiling, heating the resulting residue to about 180° C. to about 190° C. to expel all water of hydration, dispersing the residue in anhydrous ammonia to dissolve the calcium nitrate, and finally filtering the mixture to obtain the phosphate product and a filtrate containing anhydrous ammonia and calcium nitrate. The filtrate is further processed with water and carbon dioxide to produce an ammonium nitrate solution and by-product calcium carbonate. Barnes claims a 95.8 percent recovery of the P2O5 initially present in the rock, but makes no provision for the recovery of nitric acid liberated during the heating processes.

Provenance & Evidence