Abstract
Certain amount of the chromium in slags exists in the form of magnesiochromite (MgCr2O4) during the decarbonisation of stainless refining. It is mainly recovered through high temperature reduction. In this study, an interface of ferrosilicon and synthetic MgCr2O4 is made and the reduction behaviour is in-situ observed by confocal scanning laser microscope (CSLM) between 1373–1573 K. The samples were analysed afterwards through electron probe micro analyser (EPMA). Reduction of MgCr2O4 can already initiate at 1373 K within around 30 min. The heat generated from the reaction between Si and Cr2O3 can increase the local temperature of the area surrounding the reaction zone. This makes the liquefaction of Fe–Si alloy possible even at measured bulk temperatures lower than its melting point. Although Fe does not participate in the reduction of Cr, it can diffuse into the reaction zone to form a Fe–Cr–Si alloy phase, together with the reduced Cr metal and residual Si. The liquid Fe–Cr–Si alloy can act as a transfer medium for Si to promote the reduction.
