Beneficiation of Fine Coal Using the Air Table

Abstract

The increased mechanization in the underground coal-mining industry has increased the volume of fine size coal and waste (refuse) in the mined coal. Processing of run-of-mine (ROM) coal is generally done using water away from mine and in some cases the coal has to be transported a long distance to the preparation plant. Dry processing of coal can be economical as it will not utilize water and no dewatering or drying of the product will be required. The goal of this study was to develop a dry separation process for processing of coal finer than 6.3 mm . The coal sample from a mine located in Western Kentucky was used for the study. Statistical design experiments were conducted to assess the effects of operating parameters of the dry separator on product yield for a given ash content. Tests conducted with 6.3 × 3.35 mm (and 3.35 × 1.4 mm size fractions showed that the air table was able to reduce the ash from 27% to 10%–12% ash with a clean coal yield of 75%–80%. The ash rejection was about 77%–80% with a combustible recovery of around 95% indicating excellent separation efficiency. The pyritic sulfur rejection was 43%. The heat content of the 6.3 × 1.4 mm (1/4 inch × 14 mesh) coal fraction increased from 23997 kJ/kg to 29595 kJ/kg. The pyritic sulfur was reduced by about 33% with a product yield above 80%.