Abstract
Pulverized chromite ore was injected into 20 kg of molten iron from the bottom, so that the ore should be reduced by the dissolved carbon. The affects of temperature, ore injection rate, flow rate of carrier gas and powder size on the chromium yield and reduction rate were examined.
The chromium yield increased linearly with temperature, decreased with the ore injection rate and decreased linearly with the mean diameter of powder. The gas flow rate did not affect the yield. The highest yield of about 100% was obtained with the ore injection rate of less than 20 g/min at 1 680°C. From the behavior of silicon during the process, it is concluded that the oxygen transport in the melt should be the rate controlling step. The reduction process could be divided into transitory and permanent reactions. The fraction of transitory reaction was from 60 to 75% at 1 500 and 1 600°C, and more than 80% at 1 680°C. The rate of transitory reaction increased proportionally to the 2/3 power of ore injection rate, and decreased proportionally to the inverse square root of the mean diameter of powder. The gas flow rate did not affect the rate. The apparent activation energy was 46.0 kcal/mol. From these, it is suggested that several particles of powder penetrate together into the melt, accompanying some amount of gas, at the nozzle exit.
