Microindentation testing as a means of predicting lump iron ore physical properties

ABSTRACT This study utilised Vickers and Knoop microindentation testing to characterise the physical and chemical properties of a range of iron ore material types and lump ore samples. Lump ore composite microhardness (CH) and fracture toughness (CFT) correlated best with Tumble and Abrasion Indices and with Fe-total, Al2O3 and LOI contents. General trends were evident between CH/CFT and other common metallurgical indices, e.g. higher Reduction Degradation Index with lower CH. Correlations between ore group CH/CFT and the metallurgical data were generally similar, but relatively stronger, than those for the lump ores. The chemistry of mineralogical-textural sub-sets of ore groups correlated with lump ore CH/CFT. Calculating ore group CH/CFT using a textural method is therefore capable of capturing differences in ore group chemistry that relate in part to texture. A textural database of microhardness and fracture toughness can be utilised with automated optical image analysis to provide geometallurgical characterisation of iron ores.