Applicability of pre-heating techniques for recovery of garnet from garnet biotite gneiss

In mineral processing industry, the highest energy is consumed by crushing and grinding operations. However, if we can initiate micro cracks in the hard rock pieces in advance, we should be able to reduce the crushing energy and liberate useful minerals economically. Various pre-heating techniques have been tried by the scientists around the world to liberate minerals from rocks. In this investigation, pre-heating techniques were used to liberate Garnet from Garnet Biotite Gneiss. The market price of Garnet varies with the particle size. Hence, the samples were crushed and sized into industry needed three size fractions: (+250-850) μm, (+180-250) μm and (-180) μm. Afterwards, by means of Wilfley Table, Garnet was separated from rocks. Final Garnet recovery percentage was recorded for different temperatures. Furthermore, energy calculation was done for each sample to get an idea about the power consumption. It was observed that the crushing strength decreases with the temperature increment and it has been proven by identifying propagation of micro cracks in thin sections, prepared from rock samples pre-heat treated in Muffle Furnace and Microwave Oven. The analysis reveals that the preheat treated and quenched samples give higher Garnet recovery than Garnet recovered from as-received samples of Garnet rich Biotite Gneiss