Limit Moisture Content of Coal Concentrate Produced with Industrial Drainers

The process of coal suspension dewatering in centrifuges and pneumatic drainage in vacuum filters and filter presses is theoretically studied. From the condition of equal centrifugal forces and surface tension applied to liquid in a granular layer of the working element of the centrifuge bowl, the analytical relation is obtained to calculate residual concentration of liquid in the treated layer. It is shown that calculation results obtained using the relation, rated data and specifications of industrial drainers agree well. With regard to the equality between the kinetic energy applied by filtration flow in the granular layer to the liquid film in the granules and the work to overcome surface tension forces that keep the film on the surface of the granules, the analytical relation is obtained to calculate residual concentration of a liquid in the layer under pneumatic drainage. The estimates prove realistic nature of the results obtained with the latter relation as well as their agreement with the test and rated data of industrial vacuum filters and filter presses.