The smelting reduction behavior of chromite ore in molten slag of (CaO)-(SiO2)-(Al2O3)-(MgO) system by carbon in liquid iron held in graphite crucible has been studied in the temperature range of 1663 K-1953 K. The reduction rate was expressed by the zeroth-order rate equation at an early stage of smelting reduction. During this stage, both (CrO) and the rate were kept constant and unaffected by the dissolution of the ore into slag with the exception that the ore in flux contained 15 mass% (Al2O3) and 15 mass% (MgO) was reduced at 1783 K. Accordingly, the slag was considered to be saturated with (CrO). The rate decreased with an increase in (Al2O3) and (MgO) contents. In particular, it decreased with the former. On the other hand, the rate increased with (CaO)/(SiO2) ratio as it increased up to unity. When the ratio exceeded unity, the rate obtained at 1783 K was unchanged with the ratio, whereas the rate at 1903 K decreased with the ratio. The rate constant was in proportion to -0.80 power of slag viscosity.
