New Technology to Upgrade Phosphate Sources into Di-Calcium Phosphate

This paper describes a new production process that will help to reconcile the dichotomy between increasing demand for plant nutrients such as phosphorus, driven by population growth, and the decreasing quality of phosphatic raw material. The average phosphate (P₂O₅) content is reducing and the increasing presence of impurities is leading to difficulties in using the rock in conventional phosphoric acid processes. There is a need to develop new process routes adapted to these lower grade phosphate materials.

Prayon Technologies has developed and patented a new process route using sulphuric acid in diluted conditions that allows the production of di-calcium phosphate (DCP) from phosphate sources with a low P₂O₅ content and / or which are high in impurities. This DCP can either be processed as raw material for phosphoric acid production or used directly as inputs into animal feed products.

This paper describes the process and presents the results obtained from pilot testing of different raw materials. The modularity of the process enables the selective removal of some of the main impurities and produces a good quality DCP from low grade raw materials. Appropriate laboratory and pilot tests have enabled the development of the process and have confirmed the successive unit operations. The planned semi-industrial tests will be important for final optimisation and full-scale implementation.