Mineralogy of Air-Pollution-Control Residues from a Secondary Lead Smelter:Environmental Implications

摘要

The mineralogy and solubility of air-pollution-control(APC)residues from a secondary lead(Pb)smelter have been studied on samples from the Pribram smelter,Czech Republic,recycling car batteries,with the emphasis on their potential environmental effect.The presence of dominant anglesite(PbSO_4)and laurionite(Pb(OH)CI)was observed in a sintered residue from after-burning chambers(800-1000 deg C).In contrast,low-temperature Pb-bearing phases,such as KCl centre dot 2PbCl_2 and caracolite(Na_3Pb_2(SO_4)_3Cl),were detected in the major APC residue from bag-type fabric filters.Metallic elements,zinc(Zn),cadmium(Cd),and tin(Sn)were found homogeneously distributed within this residue.The formation of anglesite,cotunnite(PbCl_2),(Zn,Cd)_2SnO_4,and(Sb,As)_2O_3 was observed during the sintering of this APC residue at 500 deg C in a rotary furnace.The 168 h leaching test on filter residue,representing the fraction that may escape the flue gas treatment system,indicated rapid release of Pb and other contaminants.Caracolite and KCI centre dot 2PbCI_2 are significantly dissolved,and anglesite and cotunnite form the alteration products,as was confirmed by mineralogical analysis and PHREEQC-2 modeling.The observed Pb-bearing chlorides have significantly higher solubility than anglesite and,following emission from the smelter stack,can readily dissolve,transferring Pb into the environmental milieu(soils,water,inhabited areas).