Rotary dryer is used for such as calcite, sand minerals before grinding process for dehumidifying. Moisture is an unwanted factor during the grinding process, it may reduce the grinding capacity or become it impossible in some cases. Rotary dryers, depending on the inclination and the rotational speed of the plaster and cement kiln furnace as in progress allows the material moves through into an oven, at same time the heated air passing in the drying furnace process. Depending on required capacity and humidity of all sizes and dimensions for dryers may be designed.