Ultrasonic processing of bauxite ore to estimate its washing potential

Abstract

Silica in the form of clay present in the bauxite ore causes lot of complications in the Bayer hydrometallurgical process for the production of alumina. Therefore, bauxite is processed and washed in trommels to disintegrate and remove the clay before sending the ore as a feed to the Bayer process. Estimation of ore washing potential and the selection of cut size is essential for the establishment of a bauxite washing plant. In the current research study, a simple ultrasonic washing technique has been developed for the removal of clay and to determine the potential of an industrial washing process at various cut sizes. Four feed size fractions of clayey bauxite ore were washed in laboratory for 1, 3, 5 and 6 min using ultrasounds. After 5 min, the steady state washing conditions were observed. It was found that at 36 micron cut size, 70% mass and 77.5% alumina recovers whereas 69% of total silica moved towards the tailings streams. Cut size sensitivity shows that by increasing the cut size from 36 micron to 100 micron, nearly 5% reduction in the recoveries of total mass and alumina was observed whereas the recovery of silica slightly reduced in the concentrate.