Changing bed bulk density and other process conditions during iron ore sintering

Iron ore sintering blends in the Asia-Pacific contain significant levels of Australian ores which are lower in bulk density compared to Brazilian ores. This study explores the impact of further decreasing the bulk density of a fairly typical ore blend. This was done by introducing small amounts of a very porous ore into the blend. Measured decreases in bulk density were up to 3%. All the sinter quality parameters could be maintained or improved without the need to increase coke rate. Changes in sinter density results were not significant, indicating that the changes in bed bulk density did not have a significant effect on sinter porosity. The study was then extended to include a comparable blend and two hematite blends of higher bulk density. Decreasing green bed bulk density, bed shrinkage and sinter density did not have a detrimental effect on sinter tumble strength. The associated increase in porosity with the measured changes in sinter density is estimated to be up to 10%. Results showed that sinter density values obtained for the low bulk density mixes at increased coke addition were still lower than equivalent values for the hematite mixes. As expected flame front speed was dependent on post-ignition airflow rate and both these parameters influence sinter strength. Many blends studied have binders and results indicated that their inclusion into sinter mixes gave increased post-ignition airflow values.