A STUDY ON THE SPECIFIC RATE OF BREAKAGE OF DIFFERENT LIMESTONES FROM LAO PDR AND MALAYSIA IN A LABORATORY BALL MILL

Abstract

Effects of the different limestones and feed size on the specific rate of breakage (Si) were investigated at batch grinding conditions based on kinetic model. Six different mono-size fractions were prepared between 212 and 20 µm. The specific rates of breakage were determined from the size distributions at different grinding times, and the specific rates of breakage were compared for four limestone samples taken from different geological origin (Baling limestoneLB, Vangvieng limestone-LV, Laungprabang limestone-LL and Oudomxay limestone-LO). The results indicated that the different properties of limestone had a significant effect to the specific rate of breakage. The LB limestone gave the fastest rates of breakage because of its prominent cleavages texture, whereas the LO limestone had the slowest rates of breakage which this is due to its high content of impurities such as silica, magnesia, alumina and iron oxide. The variation of the specific rate of breakage with feed size of limestones studied show that the feed size of -75+53µm gave the highest rate of breakage compared to other feed sizes for LV, LL and LO samples; while the size fraction of -106+75µm was the best feed size for LB sample.