Investigation of phase transformations in mill scales for the purification process

Abstract For the present contribution phase transformations in primary and secondary mill scales discarded from a hot strip mill have been investigated by using synchrotron X-ray absorption spectroscopy and thermal analysis methods. Phase transformations in the scales are influenced by calcination parameters such as temperature, heating rate and isothermal interval. Magnetite, a highly interesting iron oxide for its availability in wide ranges of applications, increases its fraction after calcination at 673 K at a heating rate of 5.38 K × s −1 . This is confirmed by both characterization techniques. The calcined primary scale is found almost unchanged due to the existing predominant hematite phase. However, the additional promotion of hematite occurs at a longer isothermal calcination period at 1073 K. The majority of the results corresponded to the literature data and corroborate the assumption for a further purification process of industrial iron oxide by-products.