Synopsis(I) Reduction of molten iron oxide and Fe0 bearing slag by H2 Ar plasma was studied using water cooled Cu crucible. The sample weights were 25 to 75g, the flow rate of mixture-gas was 20 1/mm n and DC electric power of plasma was 8.3 kW. Results obtained were as follows:(1) The reduction of molten iron oxides proceeds linearly with time and the reaction rate is proportional to the partial pressure of atomic hydrogen. Therefore, it is considered that the rate determining step is the chemical reaction between Fe0 and the atomic hydrogen formed by thermal dissociation in the plasma.(2) The rate of reduction of Fe0 bearing slag is lower than that of molten iron oxide and is proportional to the Fe0 concentration in slag. It is presumed that the reduction rate is controlled by both the chemical reaction rate of Fe0 with atomic hydrogen at the gas-solid interface and the mass transport rate of Fe0 across the boundary layer between the interface and the molten slag bulk.(3) The reduction of molten iron oxide and Fe0 bearing slag by H2 Ar plasma takes place only on the cavity formed at the surface of melt by the momentum of plasma jet gas.(II) Continuous melting of pre-reduced ore powder, obtained by a fluidized bed reduction was examined using MgO crucible and H2 Ar plasma.Following results were obtained:(1) Carry-over loss of the pre-reduced ore powder during the melting in plasma arc furnace was small, when the condition of powder feeding and plasma arc were properly chosen.(2) Reduction of Fe0 in slag, accompanied in fed material, by H2-Ar plasma, could be described by a simple model of continuous melting and reduction, based on experimental results of the reduction of Fe0 bearing slag as described (1-2).With this model, the rate of reduction during continuous melting was determined.

In order to develo/l a direct reduction /11'OCeSS by fluidized bed, experimental operations of a. 11ilot plant were carried Ollt. The plant comprised multi/lie fluidized bed with both counter current and cross current contacting of ore and gas in a reactor of 25 cm inner diameter. Th e results are summarized as follows ,' (I) Stable and sintering-free continllolls operation at a maxim lim tem-/lerature q[ 900°C was carried out, using coarse partieies of H amersley iron ore (16-1 15 mesh) under a pressure q[ 7 kg /cm', C; the /lroduct of above 95°o reduction was obtained, the utilization of hy drogen gas was 17° 0 and tlze /lroductivity was 55 t/m'. d. (2) T he distribution of fractional reduction in a fluidized bed was survl!J'ed by magnetic se/laration of samples obtained from the bed. R eduction rate of Ilartieies in tlze bed was obtained directly from the distribution Cl/rve. An operation analysis was 1//{Ide on the basis of the ill[ormation obtained for /Jartieie reduction. (3) Opera tioll s using a /Jartition /Jlate designed b)' the allthors were sllccessful and dJectiue to increase the reduction degree of /noc/ucts and the

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