Overview on the removal of iron from phosphoric acid: A Comparative study

Abstract

Wet process phosphoric acid (WPA) represents the main route for phosphate fertilizers world ' s production using sulfuric acid as leaching agent. The produced acid is contaminated with various metal ions as iron, aluminum, cadmium, arsenic, uranium, etc. that limit its use in metal finishing, food, cosmetics and electronic industries. Hence, purification of the wet phosphoric acid is a challenge task. The presence of high concentration of iron in phosphoric acid leads to many problems that affect the production process as increasing the viscosity, decreasing the filtration ration rate, formation of precipitates during concentration, clarification and storage, P 2 O 5 loss in addition to decreasing the solubility of fertilizers, The present review gives an overview on the removal of iron from crude phosphoric acid by some commonly used techniques including precipitation, sorption and solvent extraction to evaluate the efficiency and drawbacks of each process. The pre-treatments of phosphoric acid are also discussed.