Castle Minerals is eyeing the potential for a material resource estimate upgrade at its Kambale graphite project in Ghana after revealing new infill and extension drilling results that include significant high-grade intercepts.
The company says the best results from 22 out of 43 drillholes in its reverse-circulation (RC) drilling campaign include intercepts of 55m at 12.6 per cent total graphitic carbon (TGC) from 11m, including 14m at 15.4 per cent from 43m and 18m at 12 per cent from 14m, with 8m at 17.2 per cent from 18m. It also featured 34m at 11.1 per cent TGC from 121m, including 10m at 14 per cent from 137m, and 27m at 10.7 per cent from 39m, including 5m at 16.7 per cent from 49m.
Management says its intersection selection is based on criteria of a 5 per cent TGC cut-off, a 2m minimum width and 2m of maximum internal dilution. The project’s current mineral resource estimate (MRE) stands at 15.6 million tonnes at 9 per cent TGC, containing 1.41 million tonnes of graphite.
Most of Castle’s latest drillhole locations were guided by the results from a horizontal loop electromagnetic (HLEM) geophysical survey undertaken last year. It was focussed on the MRE area and the company says it highlighted several modelled conductor plates that later drilling proved in most cases to be associated with graphitic mineralisation and that the graphite continues to a depth of at least 100m.
Objectives of the latest drilling included proving better definition of some of the graphitic zones modelled from the HLEM survey, which had been subject to only limited testing during the company’s drilling program last year. Management anticipates that the compilation of its latest drilling results will help qualify additional graphitic zones for inclusion in its planned MRE update.
The drilling was completed last month, with 35 of the holes for 4100m being put into the principal resource area, while additional metreage was committed to another eight holes to explore for possible resource extensions. It took the total program to 5355m of drilling and analysis for the remaining 21 drillholes is pending.
Castle has now completed 21,367m metres of drilling at Kambale, much of it within the past 18 months. It has comprised 13,614m of RC, 365m of diamond coring, 2809m of air-core (AC) drilling and 4,579m of rotary air blast drilling.
In August, the company revealed it had completed a 275 line kilometre Loupe EM survey over the broader 149-square-kilometre Kambale licence to evaluate the project for additional mineralisation in the immediate MRE area and to explore the potential for other mineralised zones.
The survey employed line lengths varying from 200m to 3950m that were spaced at variable distances of 50m, 100m and 200m. It succeeded in identifying 13 priority-one targets to be evaluated for possible additional graphitic schist occurrences and a further 33 priority-two anomalies, in addition to providing useful high-resolution information on local structural fabric and mineralisation controls.
Management noted that good correlation was obtained between the two geophysical surveys in areas of survey overlap. It now anticipates testing the new crop of 13 high-priority EM anomalies defined further afield and away from the current MRE area.
If successful, the company says it will open much of the rest of the licence area to further resource development. It is already considering preliminary auger drill testing of the targets. Metallurgical testwork is also nearing completion with results to be revealed in the coming weeks.
Once Castle’s resource upgrade is concluded, it will start its high-level technical and commercial scoping studies and search for secure end-user offtake agreements and a project development partner.
The graphite market is diverse across industrial, metallurgical, chemical and specialised areas, with each sector requiring reliable long-term supplies of graphite concentrates with specific qualities.
At present, there is no viable high-volume substitute for natural flake graphite or synthetically-manufactured forms that involve more elaborate and often higher CO2-generating processes. The immediate medium to long-term outlook for the broader graphite concentrates market is one of escalating demand and a potential supply deficit driven by its consumption in the fast-growing electric vehicle battery and stationary power storage sectors.
The market for graphite is driven primarily by the multi-billion-dollar initiatives of the United States, European Union, Korea and Japan to secure sources of critical minerals.
Castle’s Kambale project is rapidly emerging as a strategically-located and well-timed opportunity to service the forecast surge in graphite demand and meet any potential supply deficit in markets involved in global decarbonisation and consequent electrification.
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