GB1237897A - - Google Patents

Abstract

1,237,897. Aqueous solution containing ammonium phosphate, sulphate and borate. MISSISSIPPI CHEMICAL CORP. 27 Sept., 1968, No. 46089/68. Heading C1A. A concentrated aqueous solution containing the mixed ammonium salts of boric, phosphoric, and sulphuric acid is prepared by adding boric acid to an aqueous solution containing less than 55% by weight of water, and the ammonium salts of phosphoric and sulphuric acid, being free of phosphoric acid, the weight ratio of the phosphate to the sulphate being at least 5 to 1 and the weight ratio of boric acid to the sulphate being at least 5 to 1 and then adding an amount of ammonia to the solution so that at least the major portion of the phosphoric acid salt is diammonium phosphate. Preferably anhydrous ammonia is employed and the initial solution has a water content of 30-50% by weight, and at least a portion of the ammonium phosphate present in the initial solution is present as diammonium phosphate. This initial solution may be formed by adding ammonia to a mixture of phosphoric and sulphuric acid of a weight ratio of at least 5: 1 and a water content of less than 50% by weight until the solution is free of phosphoric acid. Preferably the weight ratio of boric acid to sulphate and phosphoric acid to sulphate are both from 10: 1 to 30: 1. Ammonia may be added to the mixture of acids until at least 30% by weight of the phosphoric acid is diammonium phosphate and after the addition of boric acid, ammonia is then added to the mixture until 80% by weight of the phosphate present is present as diammonium phosphate. The boric acid is preferably added as a powder but may be added as a hot concentrated aqueous solution. The mixed solution produced is added as a stabilizer in the prilling of NH 4 NO 3 , when 0À2% (NH 4 ) 2 PO 4 , 0.1% (NH 4 ) 2 SO 4 and 0.18% H 3 BO 3 are added to the nitrate.