Synthesis and Characterization of Pigment Grade Red Iron Oxide from Mill Scale

Abstract

This work aims at conversion of mill scale to produce value-added pigment grade red iron oxide by multi-step process, such as milling, acid treatment, mixing with redox reagents and calcination. In all steel re-rolling industries, mill scale is a solid waste material produced as a result of hot rolling of steel. Scales are formed due to oxidation of steel at high temperature. It can’t be used along with iron ore or bar or plate, because products obtained by using this scale contain unwanted defects of scale pitting resulting brittleness. In Bangladesh, they are mainly dumped in landfills which results environmental pollutions and other serious problems. In this study, the experimental conditions like amount of sulphuric acid and type of redox reagents were investigated in order to determine the optimal ones. The phase of as-prepared red oxide was characterized using X-ray diffraction (XRD) analysis and morphology and the particle size was characterized by scanning electron microscopy (SEM) and particle size analyzer. The results revealed that mill scale waste can be successfully converted into value-added pigment grade red iron oxide having purity 95.3 percent with satisfactory oil absorption value (29.99%) and other physical properties needed for pigment which makes the mill scale as an alternative source of iron for the preparation of pigment grade red oxide. The prepared sample was found to be hematite phase having rhombohedral crystal structure from x-ray diffraction analysis.