Characterisation of a heavy mineral-bearing sample from India and the relevance of intrinsic mineralogical features to mineral beneficiation

Iscor has developed a standard method to deal with heavy mineral-bearing sand samples in order to characterise and evaluate such samples. The aim of this paper is to present the methodology of the standard method, using a sample from a heavy mineral-bearing beach sand deposit in India as a case study. rst stage of the standard method involves preparation of the original sample to produce fundamental data, as well as to provide suitable samples for mineralogical investigation. During sample preparation the sample was deslimed, sink-floated and subjected to magnetic separation to produce four fractions, namely high susceptible magnetics, magnetics, magnetic-others and non-magnetics. Stage 2 of the method involves mineralogical investigations of these fractions in order to characterise the original sample. The investigation includes the systematic analyses and descriptions of the samples, using techniques such as XRF and XRD analyses, microscopic descriptions of the minerals and semi-quantitative analyses. Finally, based on results obtained in the previous stages, the sample is then evaluated to decide whether the specific deposit merits furthers interest or not. ng the methodology of this standard method to characterisation of the Indian sample, some important aspects were revealed. It became evident that the mineralogical and chemical compositions of the high susceptible magnetic, magnetic and magnetic-other fractions are similar in that these fractions consist mainly of ilmenite with the high susceptible magnetic fraction also containing appreciable amounts of hematite. Detailed microcopy revealed that the widespread occurrence of ilmenite in all three these fractions can be explained by variations in weathering and textural properties resulting in heterogeneous grains with varying magnetic susceptible properties. Furthermore, it was found that zircon is the main valuable mineral present in the non-magnetic fraction while considerable amounts of rutile are also present. Unfortunately, the presence of undesirable amounts of sillimanite increases the impurity levels of this fraction. However, with this being known beforehand, proper beneficiation flowline design can “clean-up” the fraction to acceptable levels. Characterisation of these intrinsic mineralogical features plays an important role in understanding the behavior of the minerals during beneficiation and the designing of optimal beneficiation routes. y, semi-quantitative mineralogical data were used to calculate the mineral composition of the sample, and together with chemical analyses, supplied a very useful and practical data set to use in evaluation of the original sample.