Breakage parameters of some minerals and coals ground in a laboratory size ceramic mill

Abstract

The kinetics of batch dry and wet grindings of calcite, barite, quartz, lignite and anthracite from feeds of sieve size 425+300 mum has been determined using a laboratory scale ceramic ball mill. The S-l values obtained were the highest (0.294 min(-1)) for anthracite and the lowest (0.071 min(-1)) for quartz when ground dry. However, the wet grinding of these materials gave higher S-l values by a factor of 1.28 for calcite, 1.15 for barite, 1.25 for quartz, 1.11 for lignite and 1.07 for anthracite comparing to the dry S-l values. The B-i,B-j values also changed for all the materials ground as dry and wet. The simulations of the product size distributions for both first-order and non-first order breakage of the materials ground were in good agreement with the experimental size distributions. There is a relationship between the S-l values and the gamma value of B-i,B-j parameter; i.e., S-l values increase when gamma values decrease, indicating that faster breakage rates of top sizes produce more fines in the finer size distribution region (-150 mum).