Effect of Basicity on the Reduction Behavior of Carbon Composite Iron Oxide Briquette

The world is gradually running short of high quality iron resources. This forces ironmaking processes to focus on the use of low quality iron ores. Carbon composite iron oxide briquettes (CCB) are one of the alternative choices. CCB enables the utilization of low quality powdered iron ores and coal, and also enhances the fast reduction rate of iron oxides by providing direct contact with coal. The iron ore and coal used for making CCB initially contain impurity components such as gangue and ash. Impurity components are generally well known to suppress contact between the iron ore and coal. In this study, the effect of basicity on the reduction behavior of CCB is discussed. Basicity in the range of 0 and 1.632 was considered. CCB mixed with reagent iron oxide and graphite was prepared to have a molar ratio C/O = 1. Reduction experiments were carried out in N-2 gas condition by heating from 200 degrees C to 1200 degrees C in an electric furnace. CO and CO2 gas were measured by a gas analyzer to analyze the reduction mechanism. In the case of CCB with a basicity less than 0.816, the degree of reduction was decreased due to the formation of fayalite phase. CCB whose basicity was higher than 1.224 also showed that the decrease of the reduction degree was due to the formation of high melting point slag. As a result, the highest value of degree of reduction was measured at the basicity in between 0.8 and 1.2.