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Castle drilling to set graphite production studies in motion

Updated: Apr 17

Drilling underway at Castle Minerals’ Kambale graphite project. Credit: File

Castle Minerals has launched a 35-hole, 4100m RC resource upgrade drilling campaign at its Ghanaian Kambale graphite deposit that boasts a JORC resource of 15.6 million tonnes at 9 per cent total graphitic carbon (TGC) for 1.41 million tonnes of graphite.

The company says a material volume of mineralisation confirmed by first-pass drilling could be added to its resource estimate with only a modest infill program. An update to the resource estimate will then be calculated and will underpin a scoping study to evaluate the merits of a long-life operation aimed at producing a fine-flake graphite product – and possibly a higher-value derivative intermediate material product – for use in the manufacturing of battery anode material.

Drilling will be completed mid-next month with assay results due in August and the updated resource estimate soon after. The program will seek to infill drill spacing to enable the inclusion of known graphite lodes in resource calculations and prove up resource extensions along strike and at depth.

Castle is excited to be a participant in the rapidly evolving electric vehicle and stationary battery industry of which graphite is a critical input. We are looking to rapidly position the Kambale Graphite Project as a credible option for the delivery of a fine flake concentrate into a market for which a major supply deficit is widely predicted. We are confident that the drilling will materially increase the Mineral Resource Estimate to underpin a planned scoping study. Castle Minerals managing director Stephen Stone

Upon completion of its drilling, Castle will upgrade its Kambale resource estimate and finish phase-two production testwork to assess the parameters of producing a commercial-grade fine-flake bulk graphite concentrate. The quality of the concentrate will be assessed at a specialist facility in Europe for its capability to produce high-value battery anode material.

The phase-two work is underway to test a 300kg sample of fresh, unweathered graphitic schist sourced from the four diamond drill core holes, which were plunged into various representative areas of the deposit.

Castle conducted its phase-one testwork in September 2021 and reported that sub-optimal, near-surface weathered graphitic schists, sourced from trenches, yielded encouraging fine-flake graphite concentrate grades up to 96.4 per cent and recoveries of up to 88 per cent. A conventional multiple grind and flotation concentration flowsheet was used.

The company’s resource upgrade and process testwork will feed into a development scoping study. It will continue to explore its ground for additional graphite deposits to further support a long-life project.

The Kambale resource has 39 per cent in the indicated category and 61 per cent in the inferred category. The deposit is hosted by 12 sub-parallel steep to moderately-dipping schist zones in a 2.3 km-long corridor, which is up to 0.5km wide. Mineralisation starts at or near surface and Castle reports little difference in grades from weathered, transitional and unweathered zones.

Management says graphite is a key component of lithium-ion battery anodes and is not readily substituted, except with synthetic graphite. There is also a projected global graphite supply issue as lithium-ion battery and hydrogen fuel cell production increases.

Graphite content of an electric vehicle is between 30kg and 65kg, with the mineral making up 30 per cent of the lithium-ion battery. Castle says Kambale is well-positioned to participate in the forecasted demand increases and should benefit from expected supply chain disruptions.

The company has timed its graphite project work to meet market conditions. Graphite lodes were discovered in the 1960s, but until recently did not have a growing market price or a projected supply side shortage.

Processing testwork and the scoping study will tell the story for Castle, but so far it is heading in the right direction.

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