The mineral slag tumble dryer is mainly composed of hot air furnace, belt conveyor, rotary drum dryer, belt conveyor, induced draught fan, cyclone dust collector, bag dust collector (or wet dust collector) and operation control system. The equipment adopts the fair current (or countercurrent) drying process. Its working principle as following: After entering the drying drum, the wet materials are spitting into the following working areas: First, the material guiding zone. The mineral slag enters this zone and contacts with high-temperature hot air to quickly evaporate water. Under the circumstance of the large lead angle guide plate, it is transferred to the next work area; the second is the copy board area.