Study of the Hydration Behavior of Synthetic Ferropericlase with LowIron Oxide Concentrations to Prevent Swelling in Steel Slags

• Steel slags generally swell when subjected to water or humidity, which prevents proper recycling in the cement or asphaltindustries. The MgO and CaO phases in steel slags are responsible for this phenomenon, as both minerals easily absorb waterto form their respective hydroxides. MgO is often present in steel slags in a solid solution with several oxides, constitutingthe so-called RO phase. This study investigates the hydration rate of an RO phase consisting of FeO and MgO called ferropericlase.The material was synthesized in a laboratory furnace by sintering a FeO–MgO powder mixture with varying initialFeO contents (approximately 10, 15, and 20 wt%). Thereafter, electron probe micro-analyzer (EPMA) and X-ray diffraction(XRD) spectroscopies were used to characterize the structure of the samples, which were mainly composed of ferropericlaseand an exsolution of magnesioferrite. Also, Mössbauer spectra showed that the total ferrous iron proportion (Fe2+/ΣFe) ofthe sintered samples was in the range of 0.55–0.72. To measure the hydration behavior, the samples in powder form werecured in an autoclave at an H2Opartial pressure of 2 atm. Thereafter, thermal gravimetric analysis (TGA) was performed tomeasure the amount of water absorbed during the autoclave curing from the mass drop associated with the dehydration ofthe hydroxide. The study found a linear correlation between the initial FeO content and the weight loss after TGA, with areduction down to 6% in the sample with an initial FeO content of 20 wt% content compared to pure MgO.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Ferropericlase

Hydration

Slag

Recycling

RO phase

Free MgO

Teknisk materialvetenskap

Materials Science and Engineering

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)