The rotary dryer is a type of industrial dryer employed to reduce or minimize the liquid moisture content of the material it is handling by bringing it into direct contact with a heated gas. The dryer is made up of a large, rotating cylindrical tube, usually supported by concrete columns or steel beams. The dryer slopes slightly so that the discharge end is lower than the material feed end in order to convey the material through the dryer under gravity. Material to be dried enters the dryer, and as the dryer rotates, the material is lifted up by a series of internal fins lining the inner wall of the dryer. When the material gets high enough to roll back off the fins, it falls back down to the bottom of the dryer, passing through the hot gas stream as it falls. This gas stream can either be moving toward the discharge end from the feed end (known as co-current flow), or toward the feed end from the discharge end (known as counter-current flow). The gas stream can be made up of a mixture of air and combustion gases from a burner, in which case the dryer is called a direct heated dryer. Based on the configuration, rotary dryers can be classified as co-current, counter current, direct fired and indirect fired. Explanation of each configuration is given below: Unique Features Efficient drying of materials with high moisture contents. Handles a wide size range of materials with extended residence times. Design permits highest possible drying temperatures. Drying, cooling or calcination. High thermal efficiency. Application Co-Current Applications : Wet feed in contact with the hottest drying gases supplied from an external source, where heat transfer is by convection. Suifilter cakes Minerals, fertilisers, Beet pulp Floatation concentrates Coal/coke Clays, phosphates Animal feeds Germ, stillage Sludges.