Effect of surfactants on bauxite residues suspensions viscosity

Measurement of the rheological property of bauxite residue samples received from an Australian alumina refinery (red mud and neutralised mud suspension) has been carried out using a Brookfield viscometer. The plant samples were treated with two anionic surfactants (sodium polyphosphate and sodium laurate) in the laboratory and the effect of the surfactants on the residues viscosity was determined. It was found that the addition of sodium laurate, prepared with an excess of sodium hydroxide causes reduction of the viscosity of both red mud and neutralised mud while sodium polyphosphate shows very little effect on either samples. The suspensions exhibit non-Newtonian behaviour and obey the power law model over a range of solid concentrations at 75 °C.