Leachability and fractionation of heavy metals in stainless steelmaking plant dusts

Abstract

The leachability and fractionation of the selected heavy metals (Cr, Cd, Pb and Zn) in the stainless steelmaking plant dusts were studied by the modified HJ/T299-2007 method, the modified TCLP test and a seven-step sequential extraction procedure. The results show that the stainless steelmaking plant dusts are considered as hazardous materials since at least one of the leachable heavy metals exceeds the corresponding limit levels of State Environmental Protection Administration of China. Pb is the most extractable heavy metals by the sequential extraction procedure, while Cr, Cd and Zn mainly presents in the residual fraction bound to spinel phase and silicates. The mobile heavy metals in the dusts, which present as the species of water soluble, exchangeable species and the species bounded to carbonates and hydroxides, can be estimated as 0.08–1.2% of Cr, 7.6%–31.8% of Cd, 34.1% of Pb, 0.052–0.4% of Zn, respectively.