Steel Slag: Chemistry, Mineralogy, and Morphology

Steel slag is a by-product of the steel industry. Understanding of the chemical, mineralogical, and morphological properties of steel slag are necessary for its use in sustainable practices. This paper provides an overview of the different types of steel slag that are generated from basic-oxygen-furnace (BOF) steelmaking, electric-arc-furnace (EAF) steelmaking, and ladle furnace steel refining processes. The mineralogical and morphological properties of BOF and electric-arc-furnace-ladle [EAF(L)] slag samples generated from two steel plants in Indiana were determined through X-ray diffraction (XRD) analyses and scanning electron microscopy (SEM) studies. The XRD patterns of both BOF and EAF(L) slag samples were very complex, with several overlapping peaks resulting from the variety of minerals present in these materials. The XRD analyses indicated the presence of free MgO and CaO in both the BOF and EAF(L) slag samples. SEM micrographs showed that the sand-size steel slag particles had subangular to angular shapes and very rough surface textures. The characteristics of the steel slag samples considered in this study are discussed in the context of a detailed review of steel slag particle properties for its potential use in geotechnical applications.