PHOSPHATE REMOVAL FROM AQUEOUS-SOLUTIONS USING RED MUD WASTED IN BAUXITE BAYERS PROCESS

The red mud wasted from the Guinean bauxite refinery was studied for p hosphate removal from model aqueous solutions of potassium orthophosph ate (OPh) and sodium tripolyphosphate (TPPh). The red mud has been tre ated with concentrated sulphuric acid. After filtration of the acid su spension, the activated mud was washed (pH 7), dried and ground to pow der. 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 pa rallel experiments using both raw and activated red mud. The dose of r ed mud added to the aqueous solutions, the contact time between them a nd initial concentrations of phosphates in the solutions for the compl ete removal of phosphates have been determined. Regression models desc ribing the process for both types of phosphate solutions have been ded uced. Copyright (C) 1997 Elsevier Science B.V.