Ettringite-Induced Heave in Chromite Ore Processing Residue (COPR) upon Ferrous Sulfate Treatment

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dc.contributor.author Dermatas, Dimitris
dc.contributor.author Chrysochoou, Maria
dc.contributor.author Moon, Deok Hyun
dc.contributor.author Grubb, Dennis G.
dc.contributor.author Wazne, Mahmoud
dc.contributor.author Christodoulatos, Christos
dc.date.accessioned 2016-03-01T13:04:17Z
dc.date.available 2016-03-01T13:04:17Z
dc.date.copyright 2006
dc.date.issued 2016-03-01
dc.identifier.issn 0013-936X en_US
dc.identifier.uri http://hdl.handle.net/10725/3229
dc.description.abstract A pilot-scale treatment study was implemented at a deposition site of chromite ore processing residue (COPR) in New Jersey. Ferrous sulfate heptahydrate (FeSO4·7H2O) was employed to reduce hexavalent chromium in two dosages with three types of soil mixing equipment. XANES analyses of treated samples cured for 240 days indicated that all treatment combinations failed to meet the Cr(VI) regulatory limit of 240 mg/kg. More importantly, the discrepancy between XANES and alkaline digestion results renders the latter unreliable for regulatory purposes when applied to ferrous-treated COPR. Regardless of Cr(VI), the introduction of reductant containing sulfate, mechanical mixing, water, acidity, and the resulting temperature increase in treated COPR promoted dissolution of brownmillerite (Ca2FeAlO5), releasing alumina and alkalinity. The pH increase caused initially precipitated gypsum (CaSO4·2H2O) to progressively convert to ettringite (Ca6Al2(SO4)3·32H2O) and its associated volume expansion under both in situ and ex situ conditions, with a maximum of 0.8 m vertical swell within 40 days of curing. While Cr(VI) treatment remains a challenge, the intentional exhaustion of the heave potential of COPR by transforming all Al sources to ettringite emerges as a possible solution to delayed ettringite formation, which would hamper site redevelopment. en_US
dc.language.iso en en_US
dc.title Ettringite-Induced Heave in Chromite Ore Processing Residue (COPR) upon Ferrous Sulfate Treatment en_US
dc.type Article en_US
dc.description.version Published en_US
dc.author.school SOE en_US
dc.author.idnumber 201205627 en_US
dc.author.woa N/A en_US
dc.author.department Civil Engineering en_US
dc.description.embargo N/A en_US
dc.relation.journal Environmental Science and Technology en_US
dc.journal.volume 40 en_US
dc.journal.issue 18 en_US
dc.article.pages 5786-5892 en_US
dc.identifier.doi http://dx.doi.org/10.1021/es0604461 en_US
dc.identifier.ctation Dermatas, D., Chrysochoou, M., Moon, D. H., Grubb, D. G., Wazne, M., & Christodoulatos, C. (2006). Ettringite-induced heave in chromite ore processing residue (COPR) upon ferrous sulfate treatment. Environmental science & technology, 40(18), 5786-5792. en_US
dc.author.email mahmoud.wazne@lau.edu.lb
dc.identifier.url http://pubs.acs.org/doi/abs/10.1021/es0604461

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