Effects of particle size and acid addition on the remediation of chromite ore processing residue using ferrous sulfate

Santhi Chandra Jagupilla, Deok Hyun Moon, Mahmoud Wazne, Christos Christodoulatos, Min Gyu Kim

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)121-128
Number of pages8
JournalJournal of Hazardous Materials
Volume168
Issue number1
DOIs
StatePublished - 30 Aug 2009

Keywords

  • Chromite ore processing residue (COPR)
  • Ferrous sulfate
  • Toxicity characteristic leaching procedure (TCLP)
  • X-ray absorption near edge structure (XANES)
  • X-ray powder diffraction (XRPD)

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