Manufacture of solid compositions comprising ammonium phosphates

A solid, particulate product comprising ammonium phosphate of N : P atomic ratio 0.95 to 1.5 and moisture content 3.5% to 12% H2O is obtained continuously by mechanically disturbing a bed of ammonium phosphate particles contained in a stationary trough by a shaft, carrying, say, pins or blades, which is rotatable so as to remove, temporarily, solid particles from the bed into the free space of the trough, adding phosphoric acid to the removed particles, allowing the acidified particles to return to the bed, and adding ammonia to said bed. An amount of solid, particulate product substantially equivalent to that produced by the addition of the reactants is removed from the bed. Wet process phosphoric acid is sprayed through pipe 6 on to particles of ammonium phosphate in the free space of trough 1 which contains a 100 lb. bed of such particles agitated by shaft 2 rotating at 112 r.p.m. and bearing flights of pins 3. Gaseous or anhydrous liquid ammonia or ammonia solution is injected into the bed from below. The N : P2O5 ratio of the product may be varied by addition of other ammonium salts and/or urea or of other acids, e.g. sulphuric or nitric. Ammonium phosphate crystals\sE0.1 mm., are removed at 9. Specifications 951,475 and 951,476 are referred to.