SINGHASINI Rotary Kiln operated at almost atmospheric pressure consists of a M.S.Cylindrical shell, ranging in length from four to ten times its diameter, into which the charge is fed continuously at one end and is discharged at the other, the movement of the material being due usually to the combined effect of inclination of the shell to the horizontal and the action of internal lifting flights during the rotation of the shell. The latter is usually provided with machined girth rings supported on suitable designed bearings. Rotation of the shell is secured by the action of suitable gearing. Materials like Gypsum , Activated Carbon , Calcium Carbonate etc are calcined in Kilns . The temperatures may be as high as 800 – 900 Deg C , refractory lining is provided in order to achieve high thermal efficiency .