METHOD FOR MAKING AMMONIUM Phosphate FERTILIZER WITH LOW CONTENT OF CADMIUM

摘要

The invention relates to a method of manufacturing ammonium phosphate fertilizer from an aqueous solution of phosphoric acid, which is characterized by a PO concentration of less than 50%, and is obtained by wet processing of phosphate ore, with the said phosphoric acid containing trace amounts of cadmium, the method includes the following stages: ( a) neutralization of the above phosphoric acid solution (1) with ammonia (2) up to a molar ratio of N / P in the range from 0.1 to 0.8, (b) the reaction between the above is partially neutralized th solution (4) and a source of sulfide (6) in order to obtain a precipitate cadmium sulfide (9); (c) separating said precipitate (9) in order to obtain a purified solution of ammoniated phosphoric acid (10), (d) ammonizing and granulating said purified solution (10) in order to obtain said fertilizer (12).