Mechanism of vanadium leaching during surface weathering of basic oxygen furnace steel slag blocks: a microfocus x-ray absorption spectroscopy and electron microscopy study

Hobson, A.J., Stewart, D.I., Bray, A.W., Mortimer, R.J.G. ORCID: 0000-0003-1292-8861, Mayes, W.M., Rogerson, M. and Burke, I.T., 2017. Mechanism of vanadium leaching during surface weathering of basic oxygen furnace steel slag blocks: a microfocus x-ray absorption spectroscopy and electron microscopy study. Environmental Science & Technology, 51 (14), pp. 7823-7830. ISSN 0013-936X

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Abstract

Basic oxygen furnace (BOF) steelmaking slag is enriched in potentially toxic V which may become mobilized in high pH leachate during weathering. BOF slag was weathered under aerated and air-excluded conditions for 6 months prior to SEM/EDS and μXANES analysis to determine V host phases and speciation in both primary and secondary phases. Leached blocks show development of an altered region in which free lime and dicalcium silicate phases were absent and Ca–Si–H was precipitated (CaCO3 was also present under aerated conditions). μXANES analyses show that V was released to solution as V(V) during dicalcium silicate dissolution and some V was incorporated into neo-formed Ca–Si–H. Higher V concentrations were observed in leachate under aerated conditions than in the air-excluded leaching experiment. Aqueous V concentrations were controlled by Ca3(VO4)2 solubility, which demonstrate an inverse relationship between Ca and V concentrations. Under air-excluded conditions Ca concentrations were controlled by dicalcium silicate dissolution and Ca–Si–H precipitation, leading to relatively high Ca and correspondingly low V concentrations. Formation of CaCO3 under aerated conditions provided a sink for aqueous Ca, allowing higher V concentrations limited by kinetic dissolution rates of dicalcium silicate. Thus, V release may be slowed by the

Item Type: Journal article
Publication Title: Environmental Science & Technology
Creators: Hobson, A.J., Stewart, D.I., Bray, A.W., Mortimer, R.J.G., Mayes, W.M., Rogerson, M. and Burke, I.T.
Publisher: American Chemical Society
Date: 19 June 2017
Volume: 51
Number: 14
ISSN: 0013-936X
Identifiers:
NumberType
10.1021/acs.est.7b00874DOI
Divisions: Schools > School of Animal, Rural and Environmental Sciences
Depositing User: Linda Sullivan
Date Added: 13 Sep 2017 14:11
Last Modified: 09 Oct 2017 08:59
URI: http://irep.ntu.ac.uk/id/eprint/31591

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