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.

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.

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. https://doi.org/10.1016/j.wasman.2018.09.046

• Journal Article Type: Article
• Acceptance Date: Sep 28, 2018
• Online Publication Date: Oct 4, 2018
• Publication Date: Nov 1, 2018
• Deposit Date: Oct 8, 2018
• Publicly Available Date: Oct 8, 2018
• Journal: Waste Management
• Print ISSN: 0956-053X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 81
• Pages: 1-10
• DOI: https://doi.org/10.1016/j.wasman.2018.09.046
• Keywords: Waste Management and Disposal
• Public URL: https://hull-repository.worktribe.com/output/1104583
• 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.
• Contract Date: Oct 8, 2018