ABSTRACT
There are some coal-based processes which utilize a vertical shaft furnace instead of a rotary kiln as the reduction reactor; these include the Kinglor Metor (KM) process and the recently propagated Midrex coal based variant — the Midrex Electrothermal Direct Reduction process. In this process, an externally heated vertical shaft furnace is employed as the reactor. The process was developed in 1971 by Kinglor-Metor SpA. The process uses screened lump ore or pellets in the size range of 6 to 25 mm. The reductant, noncoking coal (5 to 20 mm) and recycled char are employed, and if necessary, a desulfurizing agent such as limestone is also used. Each KM module consists of three twins vertical self supporting retorts (six totals) housed inside a furnace (typically 13.5 m high × 11.7 m long × 2.0 m wide). The ore, in general, should be of high grade with adequate reducibility and should not suffer excessive degradation and decripitation during reduction.
