Beneficiation of Kyanite and Sillimanite

Abstract

KYANITE and sillimanite have the same chemical compo-sition AI2O3. Si02 and are used extensively in the ref-ractory brick manufacture.Kyanite sillimanite having a minimum 60% AI2O3 and less than 1% of iron oxide prefe-rably in the form of 1/2" lumps are required by the refractory industry. Low grade sillimanites from Bihar, Maharastra, Karnataka and Orissa were tested in NML for either upgrading or lowering the iron oxide content of the samples. Depending upon the liberation size, kyanite is usually upgraded by gravity methods when the lighter siliceous gangue comprising quartz and mica are removed. When the gravity methods fail, flota-tion is employed. Iron oxides are eliminated by either reduction roast followed by magnetic separation or acid leaching.