Smelting Reduction Technologies for Direct Ironmaking

Smelting reduction is a term assigned to a group of upcoming ironmaking processes which aim at overcoming certain fundamental problems of the existing blast furnace route. These problems include dependence on large scale operation, reliance on coking coal and prepared raw materials as well as environmental pollution. A number of groups around the world, particularly in Europe, Japan, Australia, South Africa and the USA, are engaged in R & D investigations on several process concepts. Many such processes have been successfully tested in pilot/demonstration plant scale and a few of them have been commercialized. The information on smelting reduction, scattered in the literature, is still inadequate. In this paper, the authors have made on attempt to review the subject with emphasis on the current status of the process development, the process fundamentals and the critical factors which affect the production. Some of these factors are : the degree of post-combustion and pre-reduction, heat transfer, slag foaming and kinetics of slag reduction. Results of an investigation on slag reduction, which is an important step in smelting reduction, are discussed with particular emphasis on the reduction kinetics. It is shown that the reduction mechanism depends on the source of carbon.