The process involves mixing of limestone, clay, Low volatile Coal/coke breeze & other corrective materials & grinding together to a fineness of 10% retained on 170 mesh in dry condition & finally blending in a special mechanical or pneumatic blender to meet thechemical requirements of raw meal. The nodulles of required size are made in a Noduliser by adding watwr to the raw meal. These nodules are fed into vertical shaft Kiln through the revolving feed hopper, which spreads the nodules evenly round the periphery of the Kiln. As the material passes down the Kiln , it is dried, heated & burnt into clinker at about 1400*C. The clinker then passses through the cooling zone & after getting cooled, is discharged from the bottom of Kiln through rotary Air locks. The combustion air which is provided by a blower serves as cooling media for the clinker, thereby making the heat transfer more efficient. The clinker thus taken out from kiln than passes on to a ball-mill where it is ground with required quantity of gypsum to produce cement of standard quality i.e IS:269-1967. The schematic diagram of the process is given .

The critical variables for process control of a vertical shaft kiln are the chemical composition of the raw material & fineness of raw meal.

The characterstics of the raw material including fuel could be evaluated with respect of the variable like ability to nodule formation of the required size, strenght, porosity, thermal stability, uniformity etc.