Beneficiation of Kyanite from Mysore

Abstract

A sample of Kyanite received from M/s. Best & Co., Ltd., Madras, assayed 64.09% Al2O3, 26.28% SiO2,1.20% Fe2O3, 0.58% TiO2, and 0.64% alkalies (as oxides) and had a P.C.E. of 1400 ° C. The sample consisted of two distinct types of rocks- one comprising principally Kyanite and the other corundum. The Kyanite portion was associated with muscovite and quartz, whereas the corundum portion contained a soft altered mineral (margarite ?) and tourmaline. Rutile, magnetite and ochre were present in very small quantities. The sample was difficult to crush. Straight jigging of sample at -4 mesh did not give a product of high P.C.E. due to the presence of the altered mineral interlocked with corundum. Removal of the corundum-rich portion by hand-picking at a coarse size (1”) followed by jigging of the Kyanite after crushing to -4 mesh, yielded a concentrate of a P.C.E. of above 1820° C (over 37 Orton cone).It was noted that marketable grade of corundum concentrate could be obtained from the corundum portion by tabling after further grinding. Tabling of the sample after grinding to -35 mesh and hydraulic classification, also produced a table concentrate having a P.C.E. of 1820° C (37 Orton cone).