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Western Mines sees carbon capture potential in Mulga Tank

Updated: Apr 30

Western Mines Group core breakdown after 14 months’ exposure. Credit: File

Western Mines Group says recent mineral characterisation work on core samples from its Mulga Tank project highlights a potentially significant opportunity to capture and sequester atmospheric carbon dioxide.

The company believes its latest findings may represent economic and environmental benefits in the event of future development of the project on the Minigwal greenstone belt in Western Australia’s Eastern Goldfields region.

Management selected 13 quarter-core samples, each 5cm long, for powder X-ray diffraction (XRD) analysis. The samples came from five of the company’s diamond drillholes, where they intersected the ultramafic dunite host to the extensive disseminated nickel sulphides that have been identified in all diamond holes drilled to date.

XRD is an analytical technique that allows relative proportions of constituent minerals to be determined in geological samples. The latest results reveal up to 8 per cent brucite (a magnesium hydroxide) with up to 12 per cent comprising members of the hydrotalcite group minerals.

Although only a small group of samples were analysed as part of the first-pass study, the company believes the results demonstrate that the mineralogy of the Mulga Tank ultramafic complex contains critical components that could partly, or entirely, eliminate atmospheric carbon dioxide generated by, or associated with, future mining activities at the site.

The minerals of many ultramafic-hosted deposits are important in atmospheric carbon sequestration applications due to their high magnesium content that can react with large amounts of carbon dioxide to produce stable carbonate minerals, effectively sequestering this greenhouse gas.

They are well-recognised for their passive sequestration of atmospheric carbon dioxide in mine tailings at several locations worldwide and, in a particular local context, in tailings from the dunite-hosted Mt Keith nickel deposit in WA. It is reported to capture and sequester about 40,000 tonnes of carbon dioxide from the atmosphere each year through the mullock and tails from its operations.

Our Technical Director Dr Ben Grguric continues to lead and investigate further studies to enhance our understanding of the Mulga Tank Complex. This reconnaissance mineralogical work opens an interesting angle in the significant carbon capture potential of the project, greatly enhancing the green credentials and the potential economics of the project. This and other technical studies will continue in parallel with our ongoing field exploration activities. Western Mines Group managing director Caedmon Marriott

The company’s 100 per cent-owned flagship Mulga Tank project is a frontier exploration play for one or more potentially major nickel-copper-platinum group elements (PGE) deposits in the Minigwal greenstone belt – a long-overlooked and barely-explored part of the Yilgarn Craton.

The project contains the entire Mulga Tank dunite intrusive, a major ultramafic intrusion about the same size as the renowned Kambalda Dome nickel camp that contains some 35 million tonnes at 3.1 per cent nickel.

Western Mines’ exploration at Mulga Tank contains significant evidence for a working nickel-copper-PGE sulphide mineral system across a section of terrain spanning about 20km.

From geophysics and deep drilling, the company has undertaken a significant reinterpretation of the structural nature and orientation of the massive dunite ultramafic body. It now sees it as big and relatively undeformed, wedge-shaped lopolith-style intrusive that appears to be thicker in the east to about 1450m downhole, before tapering off to shallow sub-crop under about 60m of sands in the west.

Only 12 historical holes have been drilled to deeper than 200m and nearly all show nickel-copper-PGE sulphides. An additional 12km ultramafic trend remains completely unexplored for nickel-copper-PGE.

Assays from the company’s most recently reported deep hole unveiled almost continuous cumulative disseminated nickel sulphide mineralisation through more than 840m to 1464m in depth at 0.28 per cent nickel. Geochemical characterisation shows high magnesium oxide adcumulate dunite averaging 48.4 per cent magnesium oxide and 0.25 per cent volatile-free aluminium oxide through a cumulative 1374.5m downhole.

Interestingly, the company’s host rock analysis is not only indicative of a dynamic working nickeliferous system that it believes has strong potential to host one or more economic deposits, but remarkably, also comprises elements of a natural process where the host rock can “self-remediate” some of the products of its own excavation and transport in future mining operations.

The possibility of enhancing the environmental credentials of the project – possibly even to the extent of achieving net-zero carbon nickel production, in addition to a carbon-crediting byproduct revenue stream – is an interesting side study to the primary exploration focus that could benefit any prefeasibility study.

Western Mines says that has prompted it to undertake additional mineralogical characterisation work in parallel with the exploration drilling program currently underway at the project.

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