Flotation of coking coal fines for low ash metallurgical coke applications

Low Ash Metallurgical Coke (LAM Coke) finds wide applications in iron and steel foundries, non-ferrous metal castings, lead and zinc smelters, secondary steel production, chemical and ferro-alloy plants and pig iron production. One of the major specifications of the LAM coke is that ash in it should be < 11.0%. An attempt was made to produce a concentrate of < 11.0% ash from the fines (< 0.5mm), a feed to conventional flotation circuit in an operating coking coal washery, by grinding and flotation. Process parameters such as mesh-of-grind, collector and frother dosages were optimized. Coking coal sample analyzing 24.90% ash was beneficiated by grinding it to 85% passing 100 µm followed by flotation. A concentrate of 10.33% ash with 56.54% yield could be obtained using diesel as collector at 0.605 kg/t and frother at 0.0867 kg/t in the flotation which involves three-stage cleaning of rougher concentrate in order to obtain the final concentrate of required ash content. The concentrate produced could be utilized for making LAM Coke.