IMPROVEMENTS AND INTENSIFICATION OF INDUSTRIAL COCRYSTALLIZATION PROCESS FOR CADMIUM REMOVAL FROM WET PHOSPHORIC ACID

Cadmium is a natural element present in the environment, including in the soil, in the air and in seawater. The main source of cadmium in the soil is the bedrock, and the most significant man-made cadmium input comes from industrial waste. Cadmium is also naturally present in 95% of global phosphate reserves, which consist of sedimentary rock laid down in seabeds over thousands of years. The purpose of this work consists, first, to establish a baseline knowledge of the status of the cadmium removal technologies from the wet phosphoric acid and, second, to present recent results on the improvement and the intensification of the co-crystallization process for cadmium removal from phosphoric acid, which is the most studied and patented technology in this field. Thus, we have developed new co-crystallization modes (DDS & DDC) that have significantly increased the cadmium removal and the P2O5 recovery from wet phosphoric acid, saved the heat energy cost and reduced the process design. The new co-crystallization modes have upgraded the cadmium removal respectively by 34% and 37%, within a high positive impact on the P2O5 content in the wet phosphoric acid which has been increased respectively by 0.56 and 1.46 P2O5 points.