Jornal de Química Analítica Ambiental

Effective parameters on producing food grade phosphoric acid and consequently di-ammonium phosphate fertilizer from a sedimentary phosphate ore were investigated in this study. The ore characterization analysis was performed and revealed that there were 32.32% of P₂O₅ along with some elements such as iron, calcium, magnesium, chlorine, fluorine, arsenic and lead in the ore deposit. Following the initial washing experiments, two methods were used to dissolve ore and multi-step purification of phosphoric acid was performed to remove impurities. Accordingly, the solution had been concentrated using solvent extraction system. The extractant was prepared in a novel way from three-to-one mixture of Tributyl-phosphate and Isopropyl-alcohol. Kerosene was used as a solvent in these experiments. For optimization, the experiments were performed using statistical design method by DX7 software and then high purity phosphoric acid was obtained. Finally, the obtained phosphoric acid was converted to ammonium based fertilizers during optimization tests.