title: Impact of pyrolysis process on the chromium behavior of COPR.
abstract: The effect of pyrolysis process with sewage sludge on the chromium behavior of chromite ore processing residue (COPR) was examined in this study. The behavior of chromium was characterized in term of chromium oxidation test, pH-static leaching tests, column leaching test and sequential extraction test. As a sequence of pyrolysis process, the Cr(VI) in COPR was effectively reduced from 5057 mg kg(-1) for untreated COPR to 8.6 mg kg(-1) for treated COPR at temperature over 600 degrees C, which is far below the New Jersey Department of Environmental Protection regulatory limit of 240 mg kg(-1). As a result, the amount of exchangeable and carbonate-bound Cr fractions, the most mobile for the environment, were largely reduced. At the same time, the amount of the other three Cr fractions which are much less mobile become augmented. pH static test showed that the chromium in the treated COPR at pyrolysis temperature above 400 degrees C was quite stable at pH>7. Column study also indicated that only negligible amount of chromium of the treated COPR at above 600 degrees C can be released by the acid rain.
authors.affiliation: School of Environmental Science and Engineering, Shanghai JiaoTong University, Shanghai 200240, China.
authors.forename: Dalei
authors.initials: D
authors.lastname: Zhang
authors.forename: Shengbing
authors.initials: S
authors.lastname: He
authors.forename: Luwei
authors.initials: L
authors.lastname: Dai
authors.forename: Yaning
authors.initials: Y
authors.lastname: Xie
authors.forename: Deyi
authors.initials: D
authors.lastname: Wu
authors.forename: Guanhua
authors.initials: G
authors.lastname: Bu
authors.forename: Kangjin
authors.initials: K
authors.lastname: Peng
authors.forename: Hainan
authors.initials: H
authors.lastname: Kong
mesh_terms: D002857:Chromium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D012722:Sewage / Q000737:chemistry
chemical_list: D012722:Sewage; D002857:Chromium; C074702:chromium hexavalent ion