Environmental impact of the energy recovery of scrap tires in a cement kiln

The study of the impact of the use of scrap tires as a fuel substitute with respect to gaseous emissions was conducted at a cement plant which produces one million tons of cement per year. This study was conducted through the modeling of the atmospheric dispersion of contaminants emitted, with the use of the ISC-ST2 software put forth by the United States' Environmental Protection Agency. The entry data required by this Gaussian model were the meteorological data, the characteristics of the source and the pollutants, the data relating to the buildings downwash effects and the location of the receptors. The simulation of the atmospheric dispersion of pollutants allows for the evaluation of daily and annual maximum concentrations as well as the localisation of the latter, which is done just as easily at a cement kiln operating with coal only or with a combination of coal and scrap tires. The analysis of the results obtained shows whether the incorporation of tires leads to an increase or a decrease in the concentration of pollutants (particulate matter, non-condensable gases, metals, hydrogen chloride, and semi-volatile compounds). Finally, it is possible to determine ii the energy recovery of scrap tires used by a cement kiln meets environmental standards.