Reasons For Bauxite Beneficiation

Author(s): R. Moreno Rachel, F. Camperlingo Silva, C.van Deursen
The International Committee for Study of Bauxite, Alumina & Aluminium - 30 October 2012 at ICSOBA-2012 Belem,

Abstract

Caustic soda can be responsible for up to 15% of the operational cost (OPEX) in an alumina refinery. It is necessary to supplement the amount lost with the residue and the alumina and also the amount consumed during the desilication process which removes the reactive silica. Due to the high grade of reactive silica in the Brazilian bauxite ores, the Brazilian mines have included a beneficiation plant to reduce the reactive silica prior to the refinery, by removing the finer fraction of the material, usually under 37 μm. Adopting the process of washing bauxite in the beneficiation plant can reduce caustic soda consumption and equipment and piping scale in the alumina refinery (OPEX), and consequently the payback for the beneficiation plant can be less than 3 (three) years.

Besides the caustic consumption reduction, the beneficiation plant decreases the refinery energy consumption and residue generation amount, as the overall bauxite quality is improved with the removal of the reactive silica.

To select suitable equipment and technologies, it is necessary to properly characterize the bauxite. The first step is usually to do a chemical analysis per size fraction. Then further laboratory testing of each of the unit operations considered to allow scale-up will be required in order to evaluate the possible parameters in an industrial plant.