Chemical Composition and Heavy Metal Content of Portland Cement in Northern Tunisia

This study aims to determine the major elements of Portland cement type I and II (CEMI and CEMII) in a cement factory in north Tunisia and which metal elements are introduced into the production process. We determine also the metal input rate and their distribution at the entrance and exit of the process. The major elements were analyzed and the trace elements (Arsenic, barium, lead, mercury, boron, strontium, Cadmium, Chromium, copper, manganese, nickel and zinc) were identified. The concentrations of heavy metals in CEMI showed no significant difference p 0.05 with those in CEMII. All refractory metals generally tend to be incorporated into the clinker (Ba, Sr, Mn, Ni, Cu, Zn, Cr and V), while the lower part, especially volatile and semi volatile metals accumulates in the cement dust. Most metals in cement are infused with clinker. Heavy metals in the cement can originate from a variety of process in cement manufacture, including its initial presence in raw materials and fuel, incorporation into kiln refractory brick, metal erosion from the raw mill grinding process, and in other forms such as gypsum, and cement kiln dust.