Hydrothermal reaction and autoclave stability of Mg bearing RO phase in steel slag

Abstract

The relationships between the petrological features of the Mg bearing RO phase in electric arc furnace slag, its hydrothermal reactivity, and the autoclave expansion behaviour of steel slag are discussed. The Mg bearing RO phase can be classified into Mg poor wustite, Mg rich wustite, ferropericlase, and periclase, according to the FeO/MgO ratio in the RO phase. Both the reactivity of the Mg bearing RO phase with water and its expansion under autoclave conditions are controlled by the FeO/MgO ratio. Mg poor wustite phase remains stable even after treatment at 5 MPa for 72 h. In contrast, Mg rich wustite and ferropericlase react with water to form brucite and undergo uniform microex pansion under autoclave conditions even though they have poorer reactivity with water than periclase.