Clues to Eucla Basin resource

Characterisation of heavy mineral sands deposits in the South Australian portion of the Eucla Basin shows that the region has the potential to be Australia’s next big mineral sands resource.

Australia, a world leader in the production and beneficiation of heavy mineral sands, has three major economic concentrations of heavy minerals — in the south-west of Western Australia, along the continent’s east coast and in the Murray Basin.

The Eucla Basin shows potential to be our fourth heavy minerals province — and potentially the most valuable.

The Eucla Basin is currently of interest for its very high zircon concentrations, but characterisation studies carried out through the Minerals Down Under National Research Flagship have shown the deposits also have high percentages of ilmenite.

“Ilmenite is also an economically important mineral and may present an additional income stream for mineral sands processors,” CSIRO Minerals’ research project leader Dr Mark Pownceby said.

“Ilmenite can be upgraded to synthetic rutile — a feedstock for high-value titania pigment — which is used in paint and in titanium metal production.

“The complex chemistry and mineralogy of ilmenite can present significant mineral concentration and processing problems,” Dr Pownceby continues, “which means that ilmenite ores from different Australian deposits may require different methods of processing.”

For example, primary ilmenite concentrates associated with chrome-rich spinels — hard-to-remove minerals that discolour the white titania pigment — are not suitable to be upgraded using traditional sulfate-digestion methods.

Dr Pownceby and his team used automated and semi-automated microbeam-based analysis methods to characterise the ore samples.

“Analyses of the Eucla Basin samples show the ore contains altered ilmenite rather than primary ilmenite,” Dr Pownceby says.

“The samples have a similar composition to samples taken from WA deposits, which make them suitable for upgrading using the established Becher process.”

Characterising the composition and distribution of minerals in the deposit is an important first step in process design.

“Understanding exactly what you are dealing with in mineral deposits allows operators to design and install the most efficient processing solutions from the word go, rather than using a processing system that may not achieve desired outcomes.”

This article first appeared in the February 2008 issue of Process – a publication of CSIRO’s mineral resources domain.

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