Effect of Thermal Shock on Grindability of Oleic Adsorbed Flotation Placer Sillimanite

Abstract

Thermal shock is one of the most effective techniques in size reduction. The present investigation deals with the effect of thermal shock treatment on grindability and grinding characteristics of sillimanite minerals and also an attempt has been made on the overall energy saving for preparation of sillimanite flour by using ball mill. This attempt is made due to a fine dry grinding of sillimanite minerals to produce sillimanite flour, which is an energy intensive operation. It is observed from the present investigation that the particle sizes at d50 and d80 passing size in microns for thermally treated sillimanite is slightly lower than that of natural sillimanite. The study of grinding kinetics using ball mill indicate that the slope value obtained for thermally treated sillimanite is lower than the natural sillimanite, which shows that the sample responded to higher rate of grinding. The result of grindability studies reveal that the power required for thermal treatment of sillimanite is 395.36 hp and the total energy saving in the order of 8.9 % is achieved by thermal treatment of sillimanite at 900 °C for period of half an hour heating time due to development of numerous micro-cracks and fractures within the mineral grains. Hence, it is recommended to use thermally treated sillimanite for preparation of sillimanite flour (<75 µm particle size) which reduces power consumption of 8.9 %.