Abstract:
Every year, the steelmaking industry produces millions of tons of slags resulting in pollution to the environment. Among the waste, secondary metals and scales rich in iron oxides
are also thrown away. There is a need to treat the steel waste in a reasonably way to protect the environment and proposing new cheap technologies for producing advanced materials. In this study we report the morphological and structural characterization of waste
scales generated during roll milling steel process at JSC “Arcelor Mittal Temirtau”. The
raw slag and annealed at 1000 °C were measured by X-ray difraction (XRD), scanning
electron microscopy adapted with energy dispersive X-ray (SEM- EDX), magnetometry
and Mössbauer Spectroscopy (MS). Fe and O were detected by EDX as main chemical
elements and Si, S, Ca, Mg, C and Al as minimal elemental composition. XDR for the
raw sample revealed α-Fe2O3 (hematite) and Fe3O4 (magnetite) as principal and secondary phase, respectively; whereas monophasic α-Fe2O3 is detected for the scales annealed
at 1000 °C. Magnetometry measurements show the Verwey transition for the raw sample
and the Morin transition for the annealed at 1000 °C; those are fngerprints for the presence of magnetite and hematite, respectively. MS measurements for the raw sample consist
of 6 small peaks of absorption and a broad two-lines absorption peak in the central part.
The doublets are associated to the hyperfne parameters belonging to wustite. Magnetite
is related to the hyperfne parameters for two sextets in octahedral Fe2.5+ and tetrahedral
Fe3+sites and a small sextet that resembles the Mössbauer parameters of α-Fe2O3. Only a
well crystallized and weakly ferromagnetic sextet confrm the presence of α-Fe2O3 phase
for the sample annealed at 1000 °C due to thermal oxidation.
