Reduction of Iron Oxide in Sulfur Bearing Slag by Graphite.

Abstract

The effect of sulfur on the reduction rate of iron oxide in slags by graphite was investigated under argon atmosphere at 1573 K. The slag basicity (=(NCaO+NLi2O)/NSiO2; N: mol traction) was varied between 1 and 2. The sulfur concentration controlled by addition of CaS or FeS to the primary slag as changed from 0.0045 to 4.45 mass%. The initial iron content was varied between 3.89 and 9.33 mass%, and the rotation speed of graphite rod ranged from 0 to 15 s-1. It is found that the 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 content, but above 1.33% it hardly changes. Under the condition of gas hold-up factor in the foaming slag, ε=0.4, the reduction rate does not change with the condition of graphite rod rotation, but increases a little under the form-free condition. The effect of sulfur on the reduction of iron oxide becomes larger with decreasing silica activity. It is considered that under the present experimental conditions, the reduction of iron oxide in the slags is mainly controlled by chemical reaction affected by interfacial adsorption of sulfur and silica.