REDUCTION OF IRON-OXIDE IN SULFUR BEARING SLAG BY GRAPHITE

The effect of sulfur on the reduction rate of iron oxide in slags by g raphite was investigated under argon atmosphere at 1 573 K. The slag b asicity (= (N-CaO + N-Li2O)/N-SiO2 N: mol fraction) was varied between 1 and 2. The sulfur concentration controlled by addition of CaS or Fe S to the primary slag was changed from 0.0045 to 4.45 mass%. The initi al iron content was varied between 3.89 and 9.33 mass%, and the rotati on speed of graphite rod ranged from 0 to 15 s(-1). It is found that t he rate of iron oxide reduction decreases by the sulfur addition. In a slag, 20.5%Li2O-38.4% CaO-41.1%SiO2, when the sulfur content is less than 1.33%, the reduction rate decreases with the increase in sulfur c ontent, but above 1.33% it hardly changes. Under the condition of gas hold-up factor in the foaming slag, epsilon=0.4, the reduction rate do es not change with the condition of graphite rod rotation, but increas es a little under the foam-free condition. The effect of sulfur on the reduction of iron oxide becomes larger with decreasing silica activit y. It is considered that under the present experimental conditions, th e reduction of iron oxide in the slags is mainly controlled by chemica l reaction affected by interfacial adsorption of sulfur and silica.