Appendix. MIDREX® SHAFT FURNACE PROCESS BACKGROUND; The Midrex * Direct Reduction process is based upon a low pressure, moving bed shaft furnace where the reducing gas moves counter-current to the lump iron oxide ore or iron oxide , The blast furnace is a tall shaft-type furnace with a vertical stack Superimposed over a crucible-like hearth Iron bearing materials (iron ore, sinter, pellets ...