Method of the reaction of orthophosphoric acid and ammonia under pressure and fertilizers, phosphated ammoniated obtained by this process

摘要

An ammoniated phosphoric acid suitable for use as a fertilizer is produced by heating an aqueous solution of orthophosphoric acid, e.g. containing 35-65% P2O5 by wt. such as wet process acid containing 45-54% P2O5, to a temperatur of 110-160 DEG C., in a closed vessel to a maximum gauge pressure of 0.35-5.25 kg./cm.2, e.g. 0.7-2.1 kg./sq. cm. at 115-124 DEG C., but not above the boiling point at maximum pressure and then adding anhydrous ammonia at a rate to generate sufficient exothermic heat to raise the pressure above said maximum pressure to boil the solution. The ammonia is preferably added in a weight ratio of N:P2O5 in the range 1:6.4 to 1:16 and at the rate of 0.1-3 moles/min./kg. of orthophosphoric acid. An anti-foaming agent may be added, e.g. 0.2-1.0 parts of sodium dodecyl benzene sulphonate per 500 parts of orthophosphoric acid. The external heating is terminated prior to the addition of ammonia so that all the additional heat required for evaporation of water is supplied by the exothermic heat of reaction.