TY - JOUR
T1 - Assessment of calcium polysulfide for the remediation of hexavalent chromium in chromite ore processing residue (COPR)
AU - Wazne, Mahmoud
AU - Jagupilla, Santhi Chandra
AU - Moon, Deok Hyun
AU - Jagupilla, Sarath Chandra
AU - Christodoulatos, Christos
AU - Kim, Min Gyu
PY - 2007/5/17
Y1 - 2007/5/17
N2 - Bench scale and pilot scale treatability studies were conducted to evaluate the remediation of hexavalent chromium [Cr(VI)] in chromite ore processing residue (COPR) using calcium polysulfide. The results from the bench scale study indicated that a calcium polysulfide dosage twice the molar stoichiometric requirement (2×) proved effective in meeting the New Jersey Department of Environmental Protection (NJDEP) total Cr(VI) and the Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) regulatory standards. The treatment results were more effective at pH 12 than at pH 9.5. X-ray powder diffraction (XRPD) and X-ray absorption near edge structure (XANES) spectroscopy were also used to assess the treatment performance. Based on the bench scale results, an ex-situ pugmill pilot program was implemented to evaluate the applicability of the calcium polysulfide treatment on a larger scale (1000-lb batch test). The pugmill treatment results met Cr(VI) and TCLP regulatory standards over a period of 15 months. XANES analysis indicated that approximately 62% of Cr(VI) was reduced by calcium polysulfide at stoichiometric ratio of 2× after a curing period of 10 months.
AB - Bench scale and pilot scale treatability studies were conducted to evaluate the remediation of hexavalent chromium [Cr(VI)] in chromite ore processing residue (COPR) using calcium polysulfide. The results from the bench scale study indicated that a calcium polysulfide dosage twice the molar stoichiometric requirement (2×) proved effective in meeting the New Jersey Department of Environmental Protection (NJDEP) total Cr(VI) and the Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) regulatory standards. The treatment results were more effective at pH 12 than at pH 9.5. X-ray powder diffraction (XRPD) and X-ray absorption near edge structure (XANES) spectroscopy were also used to assess the treatment performance. Based on the bench scale results, an ex-situ pugmill pilot program was implemented to evaluate the applicability of the calcium polysulfide treatment on a larger scale (1000-lb batch test). The pugmill treatment results met Cr(VI) and TCLP regulatory standards over a period of 15 months. XANES analysis indicated that approximately 62% of Cr(VI) was reduced by calcium polysulfide at stoichiometric ratio of 2× after a curing period of 10 months.
KW - COPR
KW - Chromite
KW - Chromium
KW - Polysulfide
KW - Treatment
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UR - http://www.scopus.com/inward/citedby.url?scp=34247472679&partnerID=8YFLogxK
U2 - 10.1016/j.jhazmat.2007.01.012
DO - 10.1016/j.jhazmat.2007.01.012
M3 - Article
C2 - 17276597
AN - SCOPUS:34247472679
SN - 0304-3894
VL - 143
SP - 620
EP - 628
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
IS - 3
ER -