The application of PEPT has allowed a detailed study of the motion of media in a stirred grinding mill. Further analysis of this motion has identified the main differences between this media motion and the classical theory of motion within fluid mixing. Three regions have been classified within the mill and it has been previously reported that the impeller speed altered the relative position of these regions. Three different impellers were used in the previously reported study and these gave different forms of motion. The effect of media loading, slurry density, the use of media of mixed size distribution and mill baffling are reported in this paper. The influences of these on the media motion, the position of the three regions within the mill and the breakage processes are discussed. (C) 2004 Elsevier Ltd. All rights reserved.