1977 年 63 巻 14 号 p. 2269-2277
Reduction tests were performed on eight kinds of pellets produced at the actual pellet plants and four types of lump ores under the condition of the direct reduction shaft furnace, at the temperature range of 700-960°C, with reducing gas composition of H2 55%, CO 36%, CO2 5%, and CH4 4%. Reduction properties of these materials were investigated mainly on three important characteristics, that is, reducibility, generation of fine particles during reduction, and softening behaviour of sample beds.
The following results were obtained.
1) The reducibility of the pellets are fairly Well related to the amount of slag or lime addition: the higher iron content of materials, the higher degree of reduction are obtained.
Decrease of the reducibility with the increase of slag volume or lime addition is dependent on the formation of liquid phase during pellet firing process, where the certain amount of iron oxide is included.
2) In a reduction test under load, pellets with the high iron content show the higher shrinkage and the indication of clustering is observed in the reduced samples.
3) The difference of the reduction properties of burden for shaft furnace from those of ordinary blast furnace is also discussed.