Treatability of chromite ore processing waste by leaching

Abstract

Developing treatment and disposal strategies and health-based clean-up standards for chromium containing wastes continues to be an important environmental regulatory issue because of the opposing solubility and toxicity characteristics of chromium species under diverse environmental conditions. In this study, leaching characteristics of total Cr and Cr(VI) were investigated using laboratory column studies. The data obtained from the experimental studies were analysed to assess the treatability of chromite ore processing waste (COPW) by leaching and to identify the leaching strategies that enhance mass removal rates of chromium species. COPW used for laboratory soil column studies was obtained from an industrial plant producing sodium chromate in Mersin, Turkey. Laboratory investigations involved chemical characterisation of waste material and column studies. For waste characterisation, U.S. EPA toxicity characterisation leaching procedure (TCLP) was performed on COPW to determine the concentrations of metal species in the TCLP extract. For column studies, various laboratory columns containing plain COPW material, 1:1 COPW/reducing agent (elemental iron or manure) mixture and different type soils (sand, loam and clay) overlain by COPW were subjected to leaching tests using acidic, neutral and alkaline influent water to determine Cr mass leaching efficiencies. Based on the TCLP analyses, COPW is classified as hazardous waste. As a result of comparing the leaching efficiency data from twelve leaching columns, the maximum removal of total Cr was achieved by leaching COPW/manure mixture using acidic (pH 4.78) influent water. The highest Cr(VI) leaching efficiency was achieved in the columns of plain COPW and COPW/manure mixture using highly alkaline (pH 12.0) influent water. The least effective leaching efficiency for both total Cr and Cr (VI) was obtained by leaching plain COPW with neutral (pH 7.0) influent water. Land-disposal of the treated COPW material by mixing with clayey soils seems to be a viable alternative.

Keywords

chromite ore processing waste chromium leaching treatment and disposal of chromium containing waste

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References

Barnhart, J. (1997) Chromium chemistry and implications for environmental fate and toxicity. J. of Soil Contam., 6(6), 561-568.

Dugan, L. D. , Gee, H. K. & Lau, L. S. (1984) Decontamination of chromium-contaminated soils in Hawaii. Technical Rep. No. 159, Water Resources Research Center, University of Hawaii at Manoa.

Hanson, A. T. , Dwyer, B. , Samani, Z. A. & York D. (1993) Remediation of chromium containing soils by heap leaching: Column study. J of Environ. Engineer., ASCE 119(5), 825-841.

Higgins, T. E. , Halloran, A. R. & Petura, J. C. (1997) Traditional and innovative treatment methods for VI) in soils. J. of Soil Contam., 6(6), 767-797.

Infante, R. N. & Acosta, I. L. (1988) Comparison of extraction procedures for determination of heavy metals in airborne particulate matter by inductivity coupled pleasmaatomic emission spectroscopy. Atomic Spestroscopy, 9(6), 191-194.

James, B. R. (1996) The challenge of remediating chromium-contaminated soil. Environ. Sci. and Technol., 30(6), 248-251.

James, B. R. (1994) Hexavalent chromium solubility and reduction in alkaline soils enriched with chromite ore processing residue. J. of Environ. Qual., 23, 227-233.

James, B. R. , Petura, J. C. , Vitale, R. J. & Mussoline G. R. (1997) Oxidation-reduction chemistry of chromium: Relevance to the regulation and remediation of chromate-contaminated soils. J. of Soil Contam., 6(6), 569-580.

James, B. R. , Petura, J. C. , Vitale, R. J. & Mussoline G. R. (1995) Hexavalent chromium extraction from soils: A comparison of five methods. Environ. Sci. and Technol., 29(9), 2377-2381.

10.

James, B. R. & Bartlett, R. J. (1983) Behaviour of chromium in soils. IV. Interaction between oxidation-reduction and organic complexation. J. of Environ. Qual., 12(2), 173-176.

11.

Proctor, D. M. , Shay, F. C. & Scott, P. K. (1997) Health-based soil action levels for trivalent and hexavalent chromium: A comparison with state and federal standards. J. of Soil Contam., 6(6), 595-648.

12.

Technology alternatives for the remediation of soils contaminated with As, Cd, Cr, Hg, and Pb. (1997) Engineering Bulletin, Rep. No. EPA/540/S-97-500, U. S. Office of Emergency and Remedial Response, Washington, D.C.

13.

Ünlü, K. (1998) Transport of metals leaching from land-dispoded oil field wastes. Waste Management & Research, 16(6), 541-554.

14.

Vitale, R. J. , Mussoline G. R. , Petura J. C. & James, B. R. (1997) Cr(VI) soil analytical method: A reliable analytical method for extracting and quantifying Cr(VI) in Soils. J. of Soil Contam., 6(6), 581-593.