Composite pre-reduced pellet quality as affected by reductant reactivity

The composite pre-reduced (CPR) pellets have been developed to utilise stee l plant waste fines (eg. Iron ore, flue dust, mill scale, coke, coal, lime etc.) into value added product suitable for blast furnace feed as metallise d burden. This requires goad reduction (%R), appreciable metallisation (%Fe -met), sufficient handling strength and low cost for acceptance as blast fu rnace feed. These properties could be achieved by optimising the process pa rameters. In this paper, the effect of reductant reactivity has been observ ed by studying the reduction behaviour of ore-char mixed composite pellet d ue to powdered coke, coal and woodchar while keeping the molar ratio of Fe2 O3 : C as 1: 3 and identical heating schedule. It was observed that highly reactive form of carbon in woodchar rendered more reduction (similar to 46% R) compared to coke (22%R) and coal (39.5%R) but woodchar also seem to cau se severe pellet cracking than coke or coal. The cracking is mainly due to whisker type of iron growth caused by rapid reduction rate.