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Abstract

Fluidised bed technology has a wide range of process applications in chemical synthesis, combustion and gasification of fuels, drying of solids and many more. In ferrous metallurgy, fluidised bed reactors are used to reduce fine ores to metallic iron in the form of direct reduced iron (DRI). The advantage of fluidised beds is that fine iron ores can be processed directly. This avoids the energy-intensive agglomeration, sintering and pelletising of fine ores, which are required for shaft furnaces. Compared to shaft furnaces, fluidised beds are characterised by excellent mass and heat exchange between gas and solid phase, which favours reduction kinetics. The contact between gas and solids in fluidised beds is characterised by strong back-mixing of the solid phase. That is a major difference to shaft furnaces and must be considered in the process layout and conditions for reduction processes based on fluidised bed reactors. The fluid dynamics and physio-chemical fundamentals of fluidised beds for fine ore reduction are explained in the presentation. Flow schemes of industrial processes for the reduction of fine ore with fluidised bed reactors to DRI are introduced and discussed.