Formation of Chloroaromatics at a Metal Reclamation Plant and Efficiency of Stack Filter in Their Removal from Emissions

At a large metal-reclamation plant in Finland, sampling and emission analyses of polychlorophenols (PCPs), PCBs, PCDDs, and PCDFs were performed in 1990, showing that emissions from the aluminum smelter, the turning dryer, and the car shredder were of concern. Technical improvements were initiated, and the operation of gas cleaning was improved. In 1993, samples were again taken from the Al smelter and the car shredder and analyzed. Fifteen different congeners of PCPs were detected in the stack of the Al smelter; major components were 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol. PCBs were also found, due presumably to the electrical equipment in the automobiles. The isomer group profiles of PCDDs, PCDFs, polychloronaphthalenes, and polychlorodibenzothiophenes were consistent with de novo synthesis. The formation profiles of PCPs and polychlorobenzenes indicated another formation pathway, possibly in the gas phase. Gas cleaning by baghouse filtering at the Al smelter and by scrubbing at car shredder were successful in emission control at the facility.