A Review on the Modeling of Direct Reduction of Iron Oxides in Gas-Based Shaft Furnaces

Although the blast furnace process is the dominant ironmaking route to supply the feedstocks for steelmaking, a number of alternative ironmaking technologies such as the direct reduction process have grown rapidly in recent decades. This development is largely in response to the increasingly stringent emission control policies, rising costs of energy, and the increasing costs and environmental effects of coke usage. In direct reduction processes, iron oxides are reduced to iron at a temperature below its melting point. More than 79% of direct reduced iron is produced by Midrex and Energiron, both of which use gas-based shaft furnaces. A proper understanding of these processes is required to improve the performance and operation of the plants based on them. Therefore, herein, it is aimed to provide a comprehensive review of research that is carried out over the last several decades to examine the effects of the important phenomena on the performance of the gas-based shaft furnaces. The review is divided into experimental and mathematical investigations. The main features, limitations, and shortcomings of each study are discussed. Finally, the review concludes with current knowledge gaps and suggestions for further research in this thriving sector of the steel industry.