Smelting reduction studies: Scope and limitations

Abstract

It is well accepted that the blast furnace will continue as the main route for iron-making for many more years. However, its limitations have motivated researchers to look for alternative routes, particularly, those where non-coking coal is used for liquid iron production. Smelting reduction (SR), where coal and oxygen are used to produce liquid iron and power is now receiving serious attention. Several smelting reduction reactors are now operating in pilot plant scale and one or two have reached commercial status. This paper presents a brief review of the scope and limitations of laboratory smelting reduction studies reported by various workers in the literature. Importance of different factors, eg types of slag melting systems, energy consumption, nature of raw materials, reductant, slag foaming. reaction kinetics, etc are briefly discussed. In SR technologies, subsiantial reduction of iron oxide takes place in molten slag phase and this results in generation of large amounts of gases in the reactor. Therefore, slag foaming and kinetics are two important aspects. Some results of an investigation carried out recently in this laboratory are also presented. The work has been carried out using 5 - 60 per cent FeO in slag in a 35 kW capacity plasma reactor. The reduction is carried out using solid carbon as reductant, carbon being drawn from the graphite crucible only. A few experimental data on reduction by coal and pig iron are also reported. Included is a special discussion on uncertainties present in a study of this type. The paper also presents some other studies of industrial relevance which exploit iron oxide reduction in the slag phase.