This paper reports research on solving a problem in China concerning the most suitable particle size for flotation and the optimum particle size of the concentrate required for the subsequent Bayer Process. The results showed that different types of grinding medium led to different grinding effects, the following being the order of the selective grinding effect: (column + ball) > ball > rod. A novel process of "selective grinding-flotation" has been developed and has been successfully put into industrial application in China from 2003. (c) 2006 Elsevier Ltd. All rights reserved.