Perspectives of reduced water consumption in coal cleaning

Abstract

During cleaning of high-ash coal mainly “wet” processes are used which require 5 to 10 tons water consumption per 1 ton of coal. Arrangement of recycling water supply reduces demand in “fresh” water, but transportation of huge volumes of water slurry requires high energy consumption. Dry cleaning of low rank coal which has not been exposed to preliminary preparation is inefficient. It was suggested that to provide dry cleaning of high-ash coal it would be reasonable to expose it to chemical heat treatment first, and then to direct the treated coal mass for physical and mechanical cleaning to get low-ash highcaloric product. It has been determined that in black coal exposed to medium temperature pyrolysis, as well as in brown coal, improvement of incombustible mineral fraction liberation is observed that facilitates further beneficiation with the use of combination of high intensity magnetic separation and triboelectrostatic separation. It has been determined that cleaned semicoke substantially exceeds both initial and cleaned coal by its qualities as a solid fuel, and tailings of semicoke dry cleaning can be utilised.