Cement kilns are used for the pyroprocessing stage of manufacture of Portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates. Over a billion tonnes of cement are made per year, and cement kilns are the heart of this production process: their capacity usually defines the capacity of the cement plant. As the main energy-consuming and greenhouse-gas–emitting stage of cement manufacture, improvement of kiln efficiency has been the central concern of cement manufacturing technology.
Cement rotary kiln is the main equipment of calcining the cement clinker. The characteristics of a rotary kiln are simple structure, convenient and reliable control of the producing process, with little wearing parts and high running rate. It is the equipment calcining the high grade cement in the cement factory. The rotary kiln is widely used in the metallurgy, chemical industry, construction and other industries.
Cement manufacturing can be a very messy process. A number of emissions are produced in the firing of the kiln, and many cement kilns are equipped with air scrubbers to trap as many pollutants as possible. Grinding the clinkers also generates a great deal of dust, which can be an irritant if it enters the airways of people and animals. Filtration systems are used in cement grinding facilities to cut down on escaping dust, but it can be difficult to contain.