Atmospheric Emissions of Arsenic, Cadmium, Lead and Mercury from High Temperature Processes in Power Generation and Industry

High-temperature processes, such as coal and oil combustion in electric power stations and industrial plants, roasting and smelting of ores in non-ferrous metal smelters, melting operations in ferrous foundries, refuse incineration, and kiln operations in cement plants, emit several pollutants, especially those being easily volatile. Among the volatile pollutants are As, Cd, Pb and Hg. In this chapter, atmospheric fluxes of As, Cd, Pb and Hg are calculated for the above-mentioned sources in a quantitative and qualitative sense, and are based on measurements and estimates. The measurements were carried out around coal-fired power plants and copper and lead smelter complexes in Poland during the period 1975-80. Estimates were based on: (1) the chemical composition of source materials, (2) the physical-chemical properties of metals, (3) the technology employed, and (4) the efficiency and type of emission control devices utilized. Non-ferrous metal smelters appear to be a predominant source of the As and Cd emissions. Traffic is a major contributor to Pb emission, however, this source is not considered here. Significant amounts of Pb are also emitted from lead smelters. The most important sources of Hg emission include mining and smelting of non-ferrous metals, burning of fossil fuels (mainly coal), and chloralkali process for production of chlorine and caustic soda. Combustion temperature in boilers, furnaces, roasters, etc. is the key parameter affecting the amounts of As, Cd, Pb and Hg released into the atmosphere, as well as their chemical form and particle size distribution. The metallic As, Cd and Pb and their oxides and sulphides are commonly found in stack dust. Hg is released mainly in a gaseous form. Mercury associated with aerosol particles normally contributes only marginally to the total atmospheric load. High-temperature processes