CONCENTRATED COMPLEX FERTILIZERS BASED ON LOCAL RAW MATERIALS

Abstract

Phosphoric acid decomposition of phosphate raw materials underlies the production of a single phosphorus fertilizer - double superphosphate, both in-line and in a chamber method. This type of fertilizer is one of the cheapest concentrated phosphate fertilizers, suitable for use on any soil and for all crops. But for its production, high-quality phosphate raw materials are needed, such as, for example, the Khibiny apatite concentrate, and concentrated phosphoric acid. Extractive phosphoric acid from poor phosphorites, such as from Karatau phosphorites (21 % P2O5), is not suitable for the production of double superphosphate. The desire to reduce the cost of phosphorus-containing fertilizers and involve poor phosphate raw materials in their production led to the development of a new technology based on phosphoric acid activation of phosphorites. In this case, the processing of raw materials is carried out with phosphoric acid, but in quantities significantly less than is required by stoichiometry for the complete decomposition of phosphorites to obtain monocalcium phosphate. In this case, the so-called undecomposed or partially decomposed phosphates are formed. In this case, partial decomposition and granulation occurs.