Abstract:

In the process of preparing urea phosphate by wet process phosphoric acid,a large amount of urea phosphate moth-er liquor was by-produced,in which metal impurities and P₂O₅ were relatively high. Industrial grade MAP was prepared by us-ing the P₂O₅ recovered from the urea phosphate mother liquor through solvent extraction method.The effects of technological process including extraction,washing,neutralization,refining and crystallization on the yield and purity of product were in-vestigated.The optimum process conditions were confirmed: the extraction ratio（volume ratio of organic phase to aqueous phase）was 3:1,the extraction time was 5 min,the extraction temperature was 50 ℃,the washing ratio（volume ratio of organic phase to detergent）was 10:1,the neutralization pH=4.5,the saponification rate of compound acid extractant PO8 was 20%,the refining ratio（volume ratio of extract phase to aqueous phase） was 1:1,the concentration ratio was 1.36 and the crystalliza-tion temperature was 30 ℃.Under the optimum condition,industrial grade MAP with the purity of 99.45% was obtained and the P₂O₅ recovery rate in the mother liquor was 85.34%.The method had high economic benefits as its process was environmentally friendly,and the P₂O₅ recovery rate of raw materials and economic benefits were high.

Key words: urea phosphate, solvent extraction method, neutralization, crystallization, MAP