PRODUCTION OF TECHNICAL-GRADE AMMONIUM PHOSPHATES.

摘要

The present invention refers to a process for producing technical-grade ammonium phosphates, which uses as raw material: ammonium sulphate, ammonia and calcium superphosphates, the same being single, double, triple or a mixture thereof. Said process comprises a first stage, which is based on the reaction between the ammonium sulphate that is added and the single calcium phosphate contained in the superphosphates so as to obtain a single ammonium phosphate and calcium sulphate. In a second stage of the process, the ammonia is added to the mixture reacted in the first stage in order to transform a single ammonium phosphate produced in the fist stage into a di-ammonium phosphate. In this second stage, the free phosphoric acid contained in the superphosphates is also transformed into a di-ammonium phosphate. The addition of ammonia causes the Ph of the mixture to increase up to 8.00, thereby inducing the insolubilization of the following compounds: Fluorine, Magnesium, Calcium, Iron and Magnesium, which are retained by a filter. A third stage of the process consists in filtering the mixture having a Ph of 8.0. The filtered solution contains soluble ammonium phosphates free of impurities.