Effect of coal moisture on the treatment of a lignitic coal through a semi-pilot-scale pneumatic stratification jig

Dry processing methods are well known to be sensitive to the moisture content of the processed material. It is well known that cohesive forces among the particles originating from the surface moisture hinder the individual movement or appropriate stratification of particles during separation. Furthermore, high surface moisture also hampers the flow of feed material. In this study, the effect of total/surface moisture on separation of lignitic coals was investigated by using Allair stratification jig with the aim of finding possible critical surface moisture content for optimum separation. Coal samples in the size of-13 + 4 and-4 mm were processed at different particle total/surface moisture levels to recover as clean coal concentrate as possible along with obtaining tailings with minimum levels of combustibles. It is envisaged that a critical surface moisture on both classification (effective screening) and separation is available around 5.5% surface moisture (corresponding to 15% total moisture) for-13 + 4 mm whereas effective separation is not possible for the-4 mm size range even at minor changes in surface moisture of particles.