SE370926

1318224 Potassium dihydrogen phosphate FITZWILTON Ltd 10 Dec 1971 [17 Dec 1970] 59957/70 Heading C1A A process for the production of potassium dihydrogen phosphate comprises reacting potassium chloride with phosphoric acid, or condensed phosphoric acid, in an amount such that the P : K molar ratio is in the range 1À9:1 to 2À5 : 1, at a temperature of 180-325‹ C. to produce a mixture containing complex phosphates, and having a residual chlorine concentration of less than 0À1% based on the weight of the reaction mixture, which are then hydrolysed with water, or a solution containing water (e.g. wet process phosphoric acid) before precipitation. Separation of the potassium dihydrogen phosphate may be achieved by crystallization but the best method is by precipitation of the potassium dihydrogen phosphate. The preferred method is by the addition of a low boiling point water-miscible organic liquid such as alcohol, ketone or soluble ether, in a weight ratio of 0À5 : 1 to 3 : 1 of organic liquid to total solution. After precipitation the organic liquid is stripped from the acid liquor by simple distillation, although other separation means are possible.