IMPROVING SINTERING PERFORMANCE OF ORE BLEND CONTAINING PISOLITIC ORE

Laboratory studies have shown that pisolitic ore is assimilated by sin tering melts more readily than most Brazilian and Australian hematite ores; changes in the process of melt formation and properties of the h igh-temperature zone are, therefore, generally assumed to occur if the se hematite ores are replaced in a blend by pisolitic ores. Pilot-scal e studies and results obtained with commercial sinter machines show th at when Yandi pisolite is introduced into hematite ore blends sinterin g productivity often deteriorates. A study was therefore undertaken wi th the aim of improving the productivity of ore blends containing IS a nd 30 wt% Yandi. The results indicate that the loss in productivity is caused by a deterioration in green-bed permeability rather than in pr operties of the high-temperature zone. Altering the size distribution of Yandi pisolite can improve productivity, but currently produced mat erial with a top-size of -9 mm gave the best overall sintering perform ance. It was found that the productivity of blends containing Yandi ca n also be improved by increased moisture addition and enhanced green-b ed segregation, although these resulted in reduced sinter strength. It appears that the best way of improving productivity with such blends is to increase the size of the fluxes as the sinters so produced have superior strength. In addition, the benefits of adding Yandi to a sint er mix (improved reducibility and low-temperature reduction degradatio n properties) were not affected by increasing flux size. The study sug gests that a modified sintering technology with the use of coarse flux es should be adopted for ore blends that contain significant levels of Yandi pisolite.