Advanced application of BOF and SAF slags for the treatment of acid mine drainage (AMD): A comparative study

Abstract

Herein, basic oxygen furnace (BOF) and submerged arc furnace (SAF) slags were used for the treatment of acid mine drainage (AMD). Their composition, complexity, and heterogeneity permits their application in AMD remediation. To fulfil the goals of this study, batch experimental approach was adopted. This was done using a 3.5 kl reactor equipped with a propeller. Characterization of feed and product minerals were done using X-ray fluorescence (XRF), X-ray diffraction (XRD), and High resolution scanning electron microscopy coupled with energy dispersive spectroscopy (HRSEM-EDS). The obtained results showed an increase in pH, which was proportionally linked to the interaction of AMD with the slags. The pH was observed to increase from 2 to 9.4, and 9.2 for BOF and SAF slags, respectively. Furthermore, the acquired pH was conducive for the removal of chemical species from the aquasphere. This was also confirmed by PH REdox EQuilibrium (in C language) (PHREEQC). Moreover, close to 99%-removal efficacy for Fe, Al, and Mn, and ≥50% removal efficacy for sulphate were noted for individual material. This confirms that these materials have the potential to give comparative outputs and effects. PH REdox EQuilibrium (in C language) (PHREEQC) confirmed the formation of metals hydroxide and gypsum from the interaction of slags and AMD. This corroborated the XRD, XRF, and HR-SEM-EDS results. In light of the obtained results, this comparative study proved that the steel slags from different industrial operations could potentially be used for the treatment of AMD. This initiative will go a long way in unpacking viable routes for valorization and beneficiation of steel slags hence minimizing their environmental footprints.