tailieunhanh - 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. | ELSEVIER Resources. Conservation and Recycling 19 1997 11-20 resources conservation and recycling Phosphate removal from aqueous solutions using red mud wasted in bauxite Bayer s process B. Koumanova M. Drame M. Popangelova University of Chemical Technology and Metallurgy. Department of Chemical Engineering 8 Kliment Ohridski Str. 1756 Sofia Bulgaria Received 30 August 1995 revised 12 July 1996 accepted 3 August 1996 Abstract 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 time 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 1997 Elsevier Science . Keywords Red mud Phosphate removal Orthophosphate Tripolyphosphate 1. Introduction Red mud is formed as a waste during bauxite refining known as Bayer s process. Its main constituents are iron giving the red colour aluminium sodium and silica and their amounts vary according to the bauxite location. The disposal of large Corresponding author. Tel 359 2 6254409 fax 359 2 685488 0921-3449 97 Copyright 1997 Elsevier Science . All rights reserved PI S092 1 -3449 96 0 1 158-5 12 B. Koumanova et al. Resources Conservation and Recycling 19 1997 11-20 quantities of wasted red mud is a serious ecological problem. Many