Distribution of heavy metals in Portland cement production process
The potential negative impact of heavy metals on the ecosystem and human health in particular is evident. People are exposed to heavy metals through plant and animal food, water, soil and air. In industrial regions environment is usually contaminated with heavy metals. The theme of this research is to determine which metal elements are introduced into the production process of Portland cement in a cement factory in Lukavac (FCL) and to determine the metal input rate and their distribution at the entrance and exit of the process. In the process of production of cement clinker in FCL, metal elements are mostly entered by primary raw materials: limestone, marl lime, clay stone, sand; coal fly ash as secondary raw material and brown coal as regular fuel, generally come out with a finished solid products: clinker, cement and cement dust from the bag filter or gases. Coal fly ash and natural gypsum are used as additives for PC production. All refractory metals generally tend to be incorporated into the clinker, while the lower part, especially volatile and semi volatile metals (Cd, Hg), accumulates in the cement kiln dust. Most metals in cement are infused with clinker, except mercury and cobalt, which are entered from the ashes. Concentrations of metals at the entrance and exit of the kiln were determined using a Perkin - Elmer Inductively Coupled Plasma-Optical Emission Spectrometer.