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iii) smelting reduction of carbon-chromite composite pellets (formed by compacting the mixtures of Experimental studies on the smelting reduction of chromite concentrate and pulverised reductant).16-18 fluxed carbon-chromite composite pellets inThe results of the first category reveal that the early stage Fe-Cr-C-Si alloys were carried out at of reduction of chromite or Cr 2 O 3 cylinders in Fe-C(-Cr) 1520-1600°C. The reduction reaction was found to melts is controlled by mass transfer of oxygen in the liquid be favoured by high temperatures, a high lime metal phase.5,7-10 In the later stages, however, the formation addition in the pellets, a long pellet dissolution of an M 7 C 3 type carbide layer around the chromite pellets time, and a moderate melt Cr content. For a given hinders further reduction.7-9 The solid state diffusion of Fe CaO addition, however, the reduction rate initially and/or Cr through the oxide phases is suggested to be rate slowed before increasing with an increasing silica controlling in this stage.9 The presence of Si in the melt addition to the pellets. A three stage reduction can break the carbide layer and change the rate controlling mechanism is proposed. The first stage is very step from solid state diffusion to liquid phase mass transfer likely to be controlled by solid state and/or gas of oxygen.8,9 For very low melt C contents, mass transfer diffusion with an apparent activation energy of of C in the liquid metal phase may also be rate controlling.6 472 kJ mol−1 for pellets fluxed with 15%CaO andThe studies in the second category show that the 25%SiO 2 . The third stage proceeds via smelting reduction of chromite through a slag phase by C or Si mechanisms, with mass transfer in the slag phase dissolved in Fe(-Cr) melts at high temperatures is controlled possibly rate controlling.I&S/1379a by mass transfer in the slag phase.2,3,11,12 At relatively low temperatures, however, slag/metal interfacial reactions andAt the time the work was carried out Dr Merchant was in the chromite dissolution into slag may also be rate limiting.11-15

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