The rock then goes to secondary crushers or hammer mills for reduction to about 3 inches or smaller. If the process is wet, the grinding goes on in with water so that a slurry is resulted after grinding. This slurry is further mixed in mixers and pumped to the kiln. For a dry process kiln, the ground powder is send to blending silos for uniform mixing of components added during the grinding stage. The preheater is a group of cyclones placed over one another where in material comes down and hot gases goes up heating the material and calcining it in the process.
Calcination means liberating carbondioxide and converting calcium carbonate to calcium oxide.
Calciner is nothing but a duct added to give more residence time to material for calcination. This partially calcined material then comes to the kiln,which is refactory lined rotating tube having burner fitted in the other end. As the material in the kiln rolls down towards the discharge end,various reactions takes place amongst the components resulting in a mass known as clinker. This clinker is then cooled in coolers. The coolers are either planetory type or grate type.