The wet materials are sent into hopper by belt conveyor or elevator,then to the drum by feeder.The gradient of chute must be bigger than the drum to make the materials move smoothly. The drum is installed at an angle of about 3-5.Materials move from upper side to lower side,while heating medium moves from the opposite direction or the same.During this process, moisture inside the materials get vaporized.The vapour is librated by the draft fan at the end of the drum.Some lifting boards are fixed on the innerwall of the drum.They elevate and pour the materials repeatedly to accelerate the efficiency of drying.At last,the hot air is released into atmosphere through dirt catcher.