The red mud sedimentation from Bayer process of bauxite digestion is a very important step in a solid/liquid separation at industrial alumina plants. In this work a comparative study of red mud sedimentation from Alcoa/Poços de Caldas industrial plant of alumina (43 g/l of solids concentration) using different flocculants (hydroxamates and poliacrylates) was done. The concentration of poliacrylate flocculent to obtain 15 to 30 m/h sedimentation rates was smaller than the concentration of the hydroxamates flocculants, but the clarification overflow obtained with this reagent was worse than the other ones. The mixture of poliacrylamide and hydroxamate in adequate proportions can give better results of sedimentation rates and overflow clarification.
Bayer residue; bauxite; sedimentation; flocculants
