COAGULATION OF RED MUD SUSPENSIONS WITH AN INORGANIC COAGULANT

This paper deals with the coagulation of red mud (a waste product from the Bayer process to produce alumina) in water with an inorganic coagulant (FeCl//3 multiplied by (times) 6H//2O). The coagulative state is evaluated by measuring the transmittance of supernatant liquid and/or the specific volume of the sediment in suspensions after standing for 24 h. The most important factor in coagulating red mud is maintaining the pH of solutions in suspensions within the range of 7 to 8 regardless of red mud concentration because the zeta potential of red mud in this pH range is less than approximately 13 mv.