1. Product Application of Heavy Superphosphate Rotary Kiln Dryer Rotary drum dryer is a kind of drying equipment used to reduce moisture content of the material , and can be used for drying coal, coal slurry, brown coal, fly ash, gypsum, clay, Kaolin, mineral powder, slag, iron powder, mill scale, sludge, sawdust/wood chips, chicken manure, feed etc.