Effect of Calcination on the Solubility of Natural Tahoua Phosphate in Perchloric Acid and in Water

Abstract

The natural phosphate from Tahoua is a sedimentary phosphate containing a range of impurities. However, their presence in apatite makes phosphorus less available to plants. This work aims to enrich the natural phosphate from Tahoua to increase its solubility. In the first step, we carried out a heat treatment of the commercial phosphate from Tahoua. Calcination was performed in a kiln at 900°C for two hours. After treatment, we observed a loss of phosphate mass (from 8 g to 7.36 g). We then proceeded to chemically characterize the calcined phosphate by X-ray fluorescence spectrometry to determine the quantity of impurities removed from the phosphate's chemical composition. The results obtained were Al₂O₃ (from 4.64% to 0.485%), SiO₂ (from 3.35% to 0.05%), and P₂O₅ (from 20.6% to 30.8%). Finally, we dissolved the product obtained in perchloric acid and in water. The solubilization rates of calcined and merchant phosphate in perchloric acid and water were 58.75% and 16.30%, and 27.70% and 6.99%, respectively. Calcination of merchant phosphate significantly increased the concentration of P₂O₅ dissolved in both acid and water.