Mechanical activation of bauxite - €”potential and prospects in the Bayer process

Abstract

Mechanical activation of bauxite is known to have a beneficial effect on the alkali leaching of gibbsite. mechanical activation is found to be more effective, in terms of improvement in alumina recovery and minimisation of soda losses at lower temperature and soda concentration. Coupling of mechanical activation with the leaching process is an important issue in the exploitation of the beneficial effect of the activation. Two separate schemes, namely, ‘simultaneous milling and leaching’ and ‘separate milling and leaching’ have been explored. Both approaches result in comparable alumina recovery. However, greater soda loss was observed in the latter case. This is explained in terms of greater duration of leaching and its effect on the dissolution of different phases. The results show that the concept of simultaneous milling and leaching is superior in terms of leaching time, energy utilisation and simplicity of operation.