Phosphate removal from aqueous solutions using red mud wasted in bauxite Bayer's process

The red mud wasted from the Guinean bauxite refinery was studied for phosphate removal from model aqueous solutions of potassium orthophosphate (OPh) and sodium tripolyphosphate (TPPh). The red mud has been treated with concentrated sulphuric acid. After filtration of the acid suspension, the activated mud was washed (pH 7), dried and ground to powder. The influence of acid to mud ratio, and contact rime between them, on the extent of phosphate removal has been studied. The importance of the preliminary acid treatment of the red mud was established by parallel experiments using both raw and activated red mud. The dose of red mud added to the aqueous solutions, the contact time between them and initial concentrations of phosphates in the solutions for the complete removal of phosphates have been determined. Regression models describing the process for both types of phosphate solutions have been deduced. Copyright (C) 1997 Elsevier Science B.V.