Cement, how it is made. Cement kiln. Hot end of medium-sized modern cement kiln, showing tyres, rollers and drive gear 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. Emissions from the Cement Industry. A single industry accounts for around 5% of global carbon dioxide (CO2) emissions.
It produces a material so ubiquitous it is nearly invisible: cement. Cement is the primary ingredient in concrete, which in turn forms the foundations and structures of the buildings we live and work in, and the roads and bridges we drive on.