Abstract: After purification,evaporation,and crystallization,potassium dihydrogen phosphate was manufactured with mother liquid,which was prepared with calcium phosphate by-produced from gelatin plant and potassium sulfate by double decomposition reaction.Influences of the way of purification,pH of mother liquid,evaporation process,and natural cooling crystallization process on the purity and quality of product were also studied.Results showed that when sodium hydroxide was used as trash-removal agent,pH of mother liquid was 4.5,water evaporation was at 70% (mass fraction),and natural cooling crystallization was adopted,the quality of potassium dihydrogen phosphate reached the first grade requirement of the national industrial standard.

Key words: potassium dihydrogen phosphate, mother liquid, calcium hydrogen phosphate, gelatin