Slag corrosion of dolomite‐carbon refractories

Abstract

Seven industrial doloma refractory samples, coming from three European suppliers, and with different carbon, or graphite, or binder content, are subjected to the action of a slag required for the desulfurization of the steel in the secondary metallurgy at 1600°C. Three tests have been carried out within two induction furnaces. The corrosion depth, at the slag‐steel interface, has been measured; the graphite‐containing samples display a better resistance than the graphite‐free pitch or resin‐bonded refractories. Among the graphite‐containing samples correlations have been found with the carbon content and with the resistance to oxidation by CO–CO 2 at 1100–1200°C. The slag‐refractory interface has been investigated by X‐ray diffraction, optical microscopy and electron microprobe analysis; the observed phases are CaO, MgO, Ca 2 SiO 4 , Ca 3 SiO 5 and Ca 12 Al 14 O 33 (outside graphite and iron). The corrosion mechanism is linked to the reaction of slag with lime, followed by infiltration of the refractory and dispersion of periclase grains in the slag.