Regular Article

Analysis on the stability of chromium in mineral phases in stainless steel slag

¹ Key laboratory for ecological metallurgy of multimetallic mineral (Ministry of Education), Northeastern University, Liaoning, 110819 Shenyang, PR China
² School of Metallurgy, Northeastern University, Liaoning, 110819 Shenyang, PR China

^* Corresponding author: cao_longhu@163.com

Received: 12 April 2017
Accepted: 5 September 2017

Abstract

Stainless steel slag from high alloy steel is hardly used in the construction industry. The chromium leaching in unstable phase is the limiting factor for the application in the slag. The aim of this study is to investigate the stability of mineral phases in stainless steel slag. In this work, the mineral phases were firstly confirmed through experimental results by SEM-EDS and XRD. Thermodynamic calculation and leaching test were adopted to characterize the theoretical stability of mineral phases in aqueous solution. The results showed that the main phases in the stainless steel slag were spinel, melilite [solid solution of gehlenite (Ca₂Al₂SiO₇) and akermanite (Ca₂MgSi₂O₇)], dicalcium silicate, merwinite and periclase phases. It can be concluded that the minerals behave differently when dissolving in aqueous solution and the dissolution of dicalcium silicate (Ca₂SiO₄), merwinite (Ca₃MgSi₂O₈), akermanite (Ca₂MgSi₂O₇) and periclase phase could be generally higher, especially at lower pH values. In addition, the solubility of chromium in the spinel phase is considered low. The leaching test demonstrated that the formation of spinel phase can limit the leaching of chromium and the chromium existing in the silicate and periclase phases can facilitate the chromium leaching.