Mineralogical Study on Degradation of Sinter Structure at Low Temperature Reduction

Abstract

A study on degradation of sinter structure during low temperature reduction has been made by considering strain formation in mineral phases and propagation of crack in the structure.
The results obtained are summarized as follows:
(1) The degradation is observed in any sinter structure, however the cracks propagated through melting bonded sinter structures are comparatively longer than that through diffusion bonded ones.
(2) X-ray diffraction patterns indicate that the spacing of lattice planes of alumina containing skeletal hematite are shrinked compared to that of fine type hematite. One of the causes of the degradation is considered to be due to the shrinkage.
(3) X-ray line broadening analysis revealed that the value of nonuiform strain in magnetite phase obtained from 550°C reduction was higher than that from 900°C reduction. The higher nonuniform strain is considered to cause the degradation during only low temperature reduction.
(4) By a statistical analysis of the crack propagations through various mineral phases, prismatic type calciumferrite and glassy slag were estimated to be unsuitable for sinter structure.