Solidification/stabilization of electric arc furnace dust using coal fly ash - Analysis of the stabilization process

In this paper, the stabilization of electric are furnace (EAF) dust contain ing hazardous metals such as Pb, Cd, Cr or Zn is described. The treatment i nvolves a waste solidification/stabilization (S/S) process, using coal fly ash as the fundamental raw material and main binder. The article also conta ins a brief review of the most important recent publications: related to th e use of fly ash as S/S agents. The efficacy of the process has been evaluated mainly through leaching test s on the solidified products and compliance with some imposed leachate limi ts. The concentration of metals leaching from the S/S products was strongly leachate pH dependent; thus, the final pH of the leachate is the most impo rtant variable in reaching the limits and, therefore, in meeting the stabil ization goals. In this study, the dependence relationship between the leachate pH and the concentrations of metals in the leachate are analyzed; in some cases, this allows us to estimate the speciation of contaminants in the S/S solids and to understand the mechanism responsible for reduced leachability of heavy m etals from solidified wastes. (C) 2001 Elsevier Science B.V. All rights res erved.