This paper presents the
research outcomes of a magnetic mineralogical study on Hamersley iron ores.
Thermal magnetic analysis shows that typical high-grade martite-microplaty
hematite or M- (mpl H) and martite-microplaty hematite-goethite or M-(mpl H)-g
ores contain a small amount of original magnetite. A small amount of magnetite/maghemite
and pyrite/pyrrhotite/siderite may exist in typical martite-goethite (M-G) and
martite-ochreous goethite (M-oG) ores. In “the hardcap zone”, M-(H)-g ores
contain a small amount of magnetite and maghemite. Compared with XRD, thermal
magnetic analysis is not only more sensitive in identifying trace of magnetite
contained in high-grade hematite ores, but also more diagnostic in identifying
other unstable magnetic minerals like maghemite and pyrite/pyrrhotite/siderite
co-existed in the ores.