Microstructural analysis of sinter breakage

that represent loss of useful sinter (>15%). There is scope to further improve upon the
sinter strength and reduce the return fines generation. This can be achieved through better
understanding of the sinter strength and reasons behind sinter breakage. In this work,
steps involved in transportation were simulated using tumbler test and customized drop
tests to assess their impact on sinter quality. The samples were then screened in different
size fractions and samples containing freshly fractured surfaces were collected.
Microstructural analysis was conducted on the fractured surfaces, for their relative phase
distribution. Interestingly, it was observed that the finer fractions in all the cases depicted
different mineralogy than rest of the size fractions. In all the cases it exhibited less ferrite,
higher magnetite, higher silicate phase which means that these phases are more
responsible for cold strength. Ferrite phase has net like structure and thus inhibits crack
propagation. During the reduction of hematite, the growth of micro cracks starts, and as
more of hematite is reduced the propagation of these cracks increases during tumbling.
Thus magnetite is present in higher percentage in finer fractions.