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Leaching behaviour of co-disposed steel making wastes: Effects of aeration on leachate chemistry and vanadium mobilisation

Hobson, Andrew J.; Stewart, Douglas I.; Mortimer, Robert J.G.; Mayes, William M.; Rogerson, Mike; Burke, Ian T.

Authors

Andrew J. Hobson

Douglas I. Stewart

Robert J.G. Mortimer

Ian T. Burke

Abstract

Steelmaking wastes stored in landfill, such as slag and spent refractory liners, are often enriched in toxic trace metals (including V). These may become mobile in highly alkaline leachate generated during weathering. Fresh steelmaking waste was characterised using XRD, XRF, and SEM-EDX. Batch leaching tests were performed under aerated, air-excluded and acidified conditions to determine the impact of atmospheric CO2 and acid addition on leachate chemistry. Phases commonly associated with slag including dicalcium silicate, dicalcium aluminoferrite, a wüstite-like solid solution and free lime were identified, as well as a second group of phases including periclase, corundum and graphite which are representative of refractory liners. During air-excluded leaching, dissolution of free lime and dicalcium silicate results in a high pH, high Ca leachate in which the V concentration is low due to the constraint imposed by Ca3(VO4)2 solubility limits. Under aerated conditions, carbonation lowers the leachate pH and provides a sink for aqueous Ca, allowing higher concentrations of V to accumulate. Below pH 10, leachate is dominated by periclase dissolution and secondary phases including monohydrocalcite and dolomite are precipitated. Storage of waste under saturated conditions that exclude atmospheric CO2 would therefore provide the optimal environment to minimise V leaching during weathering.

Journal Article Type Article
Publication Date Nov 1, 2018
Journal Waste Management
Print ISSN 0956-053X
Electronic ISSN 1879-2456
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 81
Pages 1-10
Institution Citation Hobson, A. J., Stewart, D. I., Mortimer, R. J., Mayes, W. M., Rogerson, M., & Burke, I. T. (2018). Leaching behaviour of co-disposed steel making wastes: Effects of aeration on leachate chemistry and vanadium mobilisation. Waste Management, 81, 1-10. doi:10.1016/j.wasman.2018.09.046
DOI https://doi.org/10.1016/j.wasman.2018.09.046
Keywords Waste Management and Disposal
Publisher URL https://www.sciencedirect.com/science/article/pii/S0956053X18305889?via%3Dihub
Additional Information This article is maintained by: Elsevier; Article Title: Leaching behaviour of co-disposed steel making wastes: Effects of aeration on leachate chemistry and vanadium mobilisation; Journal Title: Waste Management; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.wasman.2018.09.046; Content Type: article; Copyright: © 2018 The Authors. Published by Elsevier Ltd.

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This work is licensed under a Creative Commons Attribution 4.0 International License.



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