GB730574A - Improvements in or relating to the manufacture of diammonium phosphate in pulverulent form - Google Patents

Abstract

<PICT:0730574/III/1> In the production of diammonium phosphate in pulverulent form by atomizing phosphoric acid and/or monoammonium phosphate solution in a current of ammonia, a supply of ammonia gas is provided at or near the top of the reaction chamber and the spray of atomized liquid is enveloped in a current of ammonia gas and water vapour recycled from the system, directed from top to bottom of the reaction chamber and effective to prevent the liquid reaching the chamber walls. The current of ammonia gas and water vapour is withdrawn from the chamber at a point remote from the spray and is reheated during the course of recycling to provide any heat necessary to obtain a dry product. As shown in Fig. 4, a reactor A is fed with ammonia gas at o and a stream of monoammonium phosphate acidified with phosphoric acid from an atomizer d. The atomizer is surrounded by a channel c through which ammonia and water vapour are fed which have been withdrawn from the reactor via a separator a, a pump b and a reheater f. The solid product is withdrawn at the bottom of the reactor. A part of the ammonia and water vapour withdrawn from the reactor may be by-passed at e to an absorption column g where entering at h it passes countercurrent to a rain of phosphoric acid fed at l. The monoammonium phosphate solution obtained is recycled to l from receiver k and in part passed by pipe j to the main reactor A. The hot vapours leaving the absorption column at F may be employed to concentrate weak phosphoric acid or to reheat, by indirect heat exchange, the ammonia and water vapour recycled through f to the reaction chamber.