Aspects of resource estimation for mineral sands deposits

Mineral sand deposits being economically exploited around the world fall into three main deposit styles; palaeo shorelines and marine placers, dunal and aeolian deposits, and alluvial deposits. Resource estimation for mineral sands follows standard estimation principles as applied to commodities throughout the Mineral Resource sector. There are, however, characteristics of mineral sands that require a slightly different approach and more emphasis on the geometallurgical characterisation to support the evaluation, Resource estimation and eventual reporting of the Mineral Resource estimate. Drilling is the main exploration and Resource definition tool used in the mineral sands industry and aside from logging and sampling, observation of hardness and induration attributes are critical aspects of drilling mineral sands deposits. Assaying is conducted on drill samples for heavy mineral (HM) content and for various particle size ranges and then further assaying or mineralogical assessment is undertaken on the HM to determine valuable heavy mineral components (typically zircon, ilmenite, rutile). The estimation of mineral sands resources requires a sound geological model before the determination of any geometallurgy based sub-domains within the mineralisation. Understanding the mineralogy and quality characteristics of deposits influences the confidence in subsequent Mineral Resource and Ore Reserve estimation and will in turn assist the Competent Person to select the appropriate cut-off-grade for Mineral Resource reporting.