Effects of thermal treatment on mineralogy and heavy metal behavior in iron oxide stabilized air pollution control residues

Mette Abildgaard Sørensen, C. Bender-Koch, M. M. Starckpoole, R. K. Bordia, M. M. Benjamin, Thomas Højlund Christensen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Stabilization of air pollution control residues by coprecipitation with ferrous iron and subsequent thermal treatment (at 600 and 900 °C) has been examined as a means to reduce heavy metal leaching and to improve product stability. Changes in mineralogy and metal binding were analyzed using various analytical and environmental techniques. Ferrihydrite was formed initially but transformed upon thermal treatment to more stable and crystalline iron oxides (maghemite and hematite). For some metals leaching studies showed more substantial binding after thermal treatment, while other metals either volatilized or destabilized with respect to leaching. Pb, in particular, exhibited increased reactivity following the formation of an ordered iron oxide structure at 900 °C. The thermal treatment had a positive effect on Cr release, which was reduced significantly at 900 °C in the presence of organic matter. Thermal treatment of the stabilized residues produced structures with an inherently better iron oxide stability. However, the concentration of metals in the leachate generally increased as a consequence of the decreased solubility of metals in the more stable iron oxide structure.
    Original languageEnglish
    Book seriesEnvironmental Science and Technology
    Volume34
    Issue number21
    Pages (from-to)4620-4627
    ISSN1382-3124
    DOIs
    Publication statusPublished - 2000

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