Chemistry, Mineralogy and Morphology of Steel Slag and Stainless Steel Slag: A Comparative Study
To enhance the understanding about the utilization of steel slags as a cementitious material, this paper presents a comparative overview for the different raw steel and stainless steel slags types in different literatures. The properties of basic-oxygen-furnace steel slag (BOF C) and electric-arc-furnace stainless steel slag (EAF S) were studied with emphasis of the following aspects: chemistry (X-Ray Florescence (XRF)); mineralogy (X-Ray Diffraction (XRD)); and morphology (Scanning Electron Microscopy (SEM)). To determine the slag activity index, the compressive strength for slag mortars was studied at 7 and 28 days. The results showed that BOF C had higher alkalinity and higher pH value than EAF S. The XRD pattern showed that BOF C contains tricalcium silicate (C3S), dicalcium silicate (C2S), calcium aluminates (Al2O3) and maynite (C12A7) as hydraulic phases. For EAF S, only the phases related to C2S are considered to be hydraulic. SEM results for BOF C and EAF S powders showed that it mostly consist of irregularly, sub- rounded to angular shaped particles. The BOF C activity index conformed the GB/T 20491-2006 standard requirements for steel slag grade one. While for EAF S, slag activity index could meet the GB/T 20491-2006 standard requirements for steel slag grade two.
Keywords:Steel slag; stainless steel slag; mineralogy; morphology; activity index.