TY - JOUR
T1 - Effects of particle size and acid addition on the remediation of chromite ore processing residue using ferrous sulfate
AU - Jagupilla, Santhi Chandra
AU - Moon, Deok Hyun
AU - Wazne, Mahmoud
AU - Christodoulatos, Christos
AU - Kim, Min Gyu
PY - 2009/8/30
Y1 - 2009/8/30
N2 - A bench-scale treatability study was conducted to assess the effects of particle size and acid addition on the remediation of chromite ore processing residue (COPR) using ferrous sulfate. The remediation scheme entailed the chemical reduction of hexavalent chromium [Cr(VI)] and the mitigation of swell potential. Leaching tests and the EQ3/6 geochemical model were used to estimate the acid dosage required to destabilize Cr(VI)-bearing and swell-causing minerals. The model predicted greater acid dosage than that estimated from the batch leaching tests. This indicated that mass transfer limitation may be playing a significant role in impeding the dissolution of COPR minerals following acid addition and hence hindering the remediation of COPR. Cr(VI) concentrations determined by alkaline digestion for the treated samples were less than the current NJDEP standard. However, Cr(VI) concentrations measured by X-ray absorption near edge structure (XANES) were greater than those measured by alkaline digestion. Greater Cr(VI) percentages were reduced for acid pretreated and also for smaller particle size COPR samples. Upon treatment, brownmillerite content was greatly reduced for the acid pretreated samples. Conversely, ettringite, a swell-causing mineral, was not observed in the treated COPR.
AB - A bench-scale treatability study was conducted to assess the effects of particle size and acid addition on the remediation of chromite ore processing residue (COPR) using ferrous sulfate. The remediation scheme entailed the chemical reduction of hexavalent chromium [Cr(VI)] and the mitigation of swell potential. Leaching tests and the EQ3/6 geochemical model were used to estimate the acid dosage required to destabilize Cr(VI)-bearing and swell-causing minerals. The model predicted greater acid dosage than that estimated from the batch leaching tests. This indicated that mass transfer limitation may be playing a significant role in impeding the dissolution of COPR minerals following acid addition and hence hindering the remediation of COPR. Cr(VI) concentrations determined by alkaline digestion for the treated samples were less than the current NJDEP standard. However, Cr(VI) concentrations measured by X-ray absorption near edge structure (XANES) were greater than those measured by alkaline digestion. Greater Cr(VI) percentages were reduced for acid pretreated and also for smaller particle size COPR samples. Upon treatment, brownmillerite content was greatly reduced for the acid pretreated samples. Conversely, ettringite, a swell-causing mineral, was not observed in the treated COPR.
KW - Chromite ore processing residue (COPR)
KW - Ferrous sulfate
KW - Toxicity characteristic leaching procedure (TCLP)
KW - X-ray absorption near edge structure (XANES)
KW - X-ray powder diffraction (XRPD)
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U2 - 10.1016/j.jhazmat.2009.02.012
DO - 10.1016/j.jhazmat.2009.02.012
M3 - Article
C2 - 19272700
AN - SCOPUS:67349278050
SN - 0304-3894
VL - 168
SP - 121
EP - 128
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
IS - 1
ER -