Microchemical investigations of dust emitted by a lead smelter

Dusts emitted by an important pyrometallurgical lead smelter have been samp led within the pipes of the grilling and furnace working units before and a fter the filtering systems, respectively. Particle size distribution, eleme ntary analyses, and X-ray powder diffraction analysis indicate PbS, PbSO4, PbSO4. PbO, Pb, ZnS small particles less than 5 mu m in size to contribute mainly to the current atmospheric pollution. Although at least 90% of dust are retained on the filters, the amounts of the respirable smaller particle s are significantly larger in the current emission. The average chemical sp eciation was found to be analogous for the dust samples collected before an d after the filters. The scanning electronmicroscopy associated with energy -dispersive X-ray analysis and Raman microspectrometry established the morp hology and chemical composition at the level of individual particles. A lot of minor compounds (alpha-PbO, beta-PbO, FeS2, FeO, FeO4, alpha-Fe2O3, FeC O3, CaSO4. 2H(2)O, CaCO3, CdS,...) were found as small heterogeneous indivi dual particles (less than 5 mu m) in the heterogeneous particles of grillin g dust. Among the homogeneous particles of furnace dust, amorphous C, beta- PbO, PbO . PbCl2 FeO, CdS, CdSO4 were often detected as homogeneous mixture s with the major compounds within the particles.