GB1245941A - Fertilizers - Google Patents

Abstract

1,245,941. Ammonium phosphate fertilizer. FISONS Ltd. 2 June, 1969 [18 June, 1968], No. 28965/68. Headings C1A and C1B. A granular fertilizer such as ammonium phosphate (NH 3 : H 3 Po 4 = 0À8 : 1 to 2À1 : 1) which may contain up to 20% by weight of (NH 4 ) 2 SO 4 , is prepared by reacting phosphoric acid containing less than 60% P 2 O 5 with NH 3 gas under superatmospheric pressure to give a fluid ammonium phosphate solution containing 15 to 20% by weight water, and subsequently expelling the solution on to particulate solids in a zone at ambient pressure and agitating the resulting mixture whereby a granular fertilizer is obtained. NH 3 gas may be passed into phosphoric acid containing 30 to 50% by weight P 2 O 5 at a temperature between ambient and 100‹ C. and which may contain some H 2 SO 4 , at a pressure of 15-50 lbs/sq. inch gauge to give monoammonium phosphate. Suitable specified particulate solids comprise at least one material selected from fertilizer materials such as those comprising at least one ammonium salt, phosphate or potassium salt, recycle undersize product, ground oversize product and onsize product from the granulation step. The water content of the fluid ammonium phosphate solution may be reduced to 10-15% by weight due to flash evaporation as the solution is expelled into the ambient pressure zone, and ammonium nitrate solution may be sprayed on to the particulate solids in conjunction with the ammonium phosphate solution. Specification 1,081,296 is referred to.