Coal Preparation » Fine Coal
This project has established the potential of an advanced flotation process unit for cleaning fine and ultrafine coal, based on the superimposition of the centrifugal flow characteristics of the hydrocyclone on the flotation process. The sub-processes of flotation comprising bubble generation, particle-bubble contact and froth pulp separation are separated for individual optimisation.
A pilot plant unit of high capacity per unit volume has been set up which is capable of consistently achieving product ash levels between 7% and 9% from a feed slurry containing 23% ash. Combustible recoveries are relatively low at 50-80% due to misplacement of a very fine bubbles carrying particles of coal to refuse around the air core and shear disruption of coarse particle-bubble aggregates resulting in loss of coal in the coarse end of the size spectrum. These issues are being addressed. The unit is easy to control and readily amenable to automatic process control. Product solids contents of 12-18% by mass have been consistently achieved.