Abstract

Leachable vanadium (V) from steel production residues poses a potential environmental hazard due to its mobility and toxicity under the highly alkaline pH conditions that characterise these leachates. This work aims to test the efficiency of anion exchange resins for vanadium removal and recovery from steel slag leachates at a representative average pH of 11.5. Kinetic studies were performed to understand the vanadium sorption process. The sorption kinetics were consistent with a pseudo-first order kinetic model. The isotherm data cannot differentiate between the Langmuir and Freundlich models. The maximum adsorption capacity (Langmuir value qmax) was 27 mg V g−1 resin. In column anion exchange, breakthrough was only 14% of the influent concentration after passing 90 L of steel slag leachate with 2 mg L−1 V through the column. When eluting the column 57–72% of vanadium was recovered from the resin with 2 M NaOH. Trials on the reuse of the anion exchange resin showed it could be reused 20 times without loss of efficacy, and on average 69% of V was recovered during regeneration. The results document for the first time the use of anion exchange resins to remove vanadium from steel slag leachate. As an environmental contaminant, removal of V from leachates may be an obligation for long-term management requirements of steel slag repositories. Vanadium removal coupled with the recovery can potentially be used to offset long-term legacy treatment costs.

Highlights

  • Steelworks slags are an important industrial by-product, with an annual global production of 170e250 million tonnes (USGS, 2015), and an estimated total production of 5 Gt since 1840 (WSA, 2015)

  • The aim of this study was to test the efficiency of a basic anion exchange resin for vanadium removal and recovery from steel slag leachates

  • The steel slag leachate was produced in the laboratory via leaching a bulk sample of basic oxygen furnace (BOF) steel slag collected from Yarborough, Scunthorpe, UK (53.588192N, À0.593582W) with

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Summary

Introduction

Steelworks slags are an important industrial by-product, with an annual global production of 170e250 million tonnes (USGS, 2015), and an estimated total production of 5 Gt since 1840 (WSA, 2015). Vanadium is a group 5 transition metal that is widely used in the chemical and metal alloy industries (Ker€anen et al, 2013; Li et al, 2013; Mirazimi et al, 2015; Navarro et al, 2007; Zhou et al, 2011) It has three stable oxidation states: V(III), V(IV) and V(V) (ATSDR, 2012), and it is present in steel slag predominantly as V(IV), but during leaching it can be oxidized to V(V) (Chaurand et al, 2007), which is the most toxic form and a possible human carcinogen (IARC, 2006). Gomes et al / Journal of Environmental Management 187 (2017) 384e392

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