Reduction of iron ore pellets used in the Fastmet process

The Fastmet process is a direct coal-based reduction process whereby pelletized mixtures of iron ore and coal are reduced by radiative heat in a rotating hearth furnace. The pellets are spread over the floor of the furnace in one or more layers and radiated from the ceiling. Available data indicates that the thermal exchange to and from the pellets and between pellets is radiation-dominated, and that it is the efficiency of supply of the necessary reduction heat that limits the processing rate. An estimated time of 6 minutes is required to reduce a single layer of pellets 20 mm in diameter under the envisaged circumstances. If more than one layer of pellets is used, the upper layers will shield lower layers. Estimates are made for the effect of this shielding on roasting time.