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High-performance graphite given green light for Castle

Updated: Apr 17

Castle Minerals processed graphite has been incorporated into a Swagelok T-cell for performance tests. Credit: File

Castle Minerals (ASX: CDT) says recent electrochemical testwork has shown that natural flake graphite from its Kambale project in Ghana is suitable for the manufacture of lithium-ion batteries and other applications.

Within just two years, the company has defined a 22.4-million-tonne resource grading 8.6 per cent total graphite content (TGC) and it has now proved mined material can be upgraded into a valuable 95 per cent loss on ignition (LOI) graphite concentrate through conventional processing.

Management says preparatory work involved initial production of a natural flake concentrate grading 95 per cent LOI that was produced by Perth-based company Metallurgy under the supervision of Independent Metallurgical Operations. Then in Germany, renowned graphite specialists ProGraphite further purified the flake concentrate to 99.97 per cent LOI.

Downstream processing involved a sample of the uncoated micronized and spheronised 99.97 per cent LOI product (SPG) provided by ProGraphite, which was then specially formed to produce a “Swagelok T-cell”.

A Swagelok T-cell is a low cost, high-quality specific cell design comprising five parts to facilitate lithium-ion battery research. It provides a simulated lithium-ion battery configuration for electrochemical testwork.

This is all happening at a time when the world needs considerably more fine natural flake graphite to underpin forecasts of very strong growth in the uptake of electric vehicles. Castle’s view remains that the graphite market is fundamentally very robust and graphite is definitely a commodity to watch this year and into the longer term.
Castle Minerals managing director Stephen Stone

The testwork on the Kambale flake graphite SPG material included physical and electrochemical properties and performances relating to the chargeability, durability, stability, reversible capacity and other parameters.

Management says its graphite samples were left uncoated for the testwork, with coating of the spheroidised material intended to be a final process where it would be tailored to the product once its performance characteristics are known.

Management says it is now working on a long-term development strategy for its Kambale mining operation. It will involve a detailed look at other supplies of similar material and the comparative geographic locations, product performances and categories, national jurisdictions, security, infrastructure and local environments.

The overarching review is expected to deliver a basis for a definitive feasibility study (DFS). At the current early stage of development, it is expected to comprise an initial low-cost, campaign mined, modular and easily scalable operation.

Castle expects the operation to produce marketable fine flake graphite concentrate on-site, in addition to other high-value downstream products using available grid power where local cheaper hydroelectric power generation contributes about 40 per cent. It means Kambale could find itself among very few “green” graphite projects globally.

Stone has met with the Ghanaian Government and potential contractors and says the project has a high level of local support and is compatible with other local lithium plays such as Atlantic Lithium’s Ewoya lithium operation.

The Ghanaian Government has provided significant financial support to Atlantic and its local subsidiaries by way of US$32.9 million (AU$49.7 million) through its mineral income investment fund – part of the government’s broader ambition to establish West Africa’s first critical minerals hub.

The company expects to see a significant increase in available mining-related services in the country with the imminent start-up of Cardinal Namdini Mining’s gold mine in northern Ghana and the likely kick-off on construction this year at the Black Volta Gold project, just 40km north of Kambale. Both operations are expected to add to the already good infrastructure near Kambale, including hydro power.

The Kambale mineral resource was updated last October to the estimated 22.4 million tonnes grading 8.6 per cent TGC containing 1.939 million tonnes of graphite, with 43 per cent of the tonnage residing in the indicated category.

Recent third-party offtake deals between non-Chinese producers of primary natural graphite concentrate and downstream manufacturers of natural graphite conductive additives for anodes, cathodes and other secondary battery chemistries signal a trend where end users are distancing themselves from single-source dependency. The United States and European Union are also establishing high-ticket initiatives to help establish independent supply chains of critical minerals such as graphite.

Management considers its development of Kambale could be ideally timed and well-placed to service existing and emerging markets.

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