PURPOSE: To dry, classify and crack wet raw material and obtained dried powder efficiently after grinding and classifying by a method wherein at the lower part of a sucking and exhausting hole a classifying is installed and the gap between the bottom rotating pan and a neighbor rotting dish can be changed freely and a classifier is attached to a grinder.

CONSTITUTION: When wet raw material is thrown on a rotating pan from a supply hole 11, the material falls downwards and exchanges heat with hot gas and comes in contact with upward and high velocity hot gas from a blade ring and is blown up upwards. Fine particles pass through the blades of a rotating separator 12 and are discharged from a sucking and exhausting hole 13 outside the device. In order to discharge middle size particles and coarse particles stored in the device, the bottom rotating pan is lowered to expand a gap. As the amount of gas flowing into the gap is increased, the amount of hot gas flowing into a blade ring is reduced to reduce a gap velocity and the middle size particles and the coarse particles fall down and move toward a screw conveyor 15. The middle size particles and the coarse particles discharged by the conveyor 15 is ground by a ball mill 300 and fine particles are conveyed by air and the gas containing dust enters into a classifier 400 and the fine particles are sent to a dust collector 500 and recovered.