Process Name

Cement Producing


Portland cement is manufactured from a clay and limestone mixture that is calcined in kilns. Portland cement does not contain free silica. Kiln emissions include carbon monoxide and sulfur dioxide. The hexavalent chromium found in cement may originate from the refractory lining of the kilns. [ILO Encyclo: Cement and Concrete] Raw materials in Portland cement: limestone and clay (source of alumino-silicate); secondary raw materials (shale, sand, iron ore, bauxite, fly asy, and slag); Typical composition: 61-67% Calcium oxide, 19-23% Silicon dioxide, 2.5-6% Aluminum oxide, 0-6% Ferric oxide, 1.5-4.5% Sulfate; "In Scandinavia, France, and the UK, the level of chromium(VI), which is considered to be toxic and a major skin irritant, may not exceed 2 ppm." [Wikipedia: Portland cement]



Related Information in Haz-Map

Hazardous agents associated with this process: