THE REDUCING VELOCITIES OF VARIOUS IRON ORES BY CO GAS

Abstract

The reducing velocities by CO gas were tested for a kind of limonite ore, 5 kinds of hematite ores, 4 kinds of magnetite ores and a kind of heating furnace cinder. Each ore was equally granulated in about 1m.m. dia. and 1c.c. of the granulated sample was taken in each experiment. 100c.c. of the mixed gas of CO(35%) and N2(65%) per min. were passed for some hours through the sample which was kept at 800°C. or 1000°C. in an electric resistance furnace. The % of CO₂ in the exhausted gas from the sample was analysed every 10mins. The amount of CO₂ indicated the amount of the oxygen taken from the iron ore, and thus the reducing velocities of the various ores were calculated.
The reducing velocities of the limonite and hematite ores which contained not much silica, were more rapid than those of the magnetite ores and the heating furnace cinder, the velocity of the last being the slowest.
Also the reducing velocities from Fe₃O₄ to FeO and those from FeO to (Fe. FeO) were compared in each ore and averaged. Averaging the ores which contained over 50% of iron (51 to 70% Fe) it was seen that the reducing velocity (at 1000°C. or 800°C) from Fe₃O₄ to FeO was about 2.2 times (1.4 to 3.1 times) greater than that from FeO to (Fe. FeO) and the ratio was greater for the siliceous hematite ores compared with the hematite ores which contained not much silica.
Again the degree of the increment of the reducing velocities of the various ores at 1000°C. against that at 800°C. was compared, and it was found that the degree of the increment for the magnetite ores was much greater than that of the hematite ores.
The conditions of easily reducible ore were ascertained from our experiment.