Mount Peake Graphite
The BGC1 and G34 electromagnetic targets were first identified from a GEOTEM (airborne electromagnetic survey) carried out for Falconbridge Pty Ltd in 2003, and confirmed in a 2012 HeliTEM survey conducted for TNG.
TNG drilled an RC hole into the BGC1 target in 2010 and intersected minor sulphides, including pyrite, chalcopyrite and pyrrhotite within a graphite rich zone. The G34 target was drilled in 2011 but drilling difficulties resulted in the EM target not being adequately tested, though the end of the hole finished in a strongly graphitic schist.
Preliminary metallurgical work on RC samples from the BCG1 hole provided significant encouragement with upgrading by floatation to 70% Total Graphitic Carbon, however diamond core sampling was required for more rigorous assessment and to determine the quality and commercial potential of the graphite.
Diamond drill-hole 14MPDDHBGC1W1 wedged off the old BGC1 RC hole and provided core from 186.8m to 298.4m down-hole. The interval from 240.0m to 285.3m (45.3m) was continuously graphitic with the visual grade increasing from the extremities towards the centre (at approximately 266m down-hole).
The host rock is a quartz-biotite-andalusite schist from the Paleoproterozoic Lander Rock Beds in the Aileron Province.
Significant intersections at the BGC1 target were:
At a 4% C graphite cut-off:
14MPDDHBGC1W1 246.00 to 285.30m 39.70m @ 5.13% C graphite
At a higher cut-off of 5% C graphite:
14MPDDHBGC1W1 248.00 to 254.00m 6.00m @ 5.33% C graphite; and
14MPDDHBGC1W1 266.70 to 285.30m 18.60m @ 5.32% C graphite
The best graphite grade was 8.33% C graphite, while most is medium grade in the 3-6% range.
The graphite zones at the BGC1 target all fall within the high conductivity modelled shell that extends over 1000m by 600m. Significant additional volumes of high conductivity ground occur to the south and west of the existing holes.
The G34 target was tested by diamond drill-hole 14MPDDHG34W1 and graphite was seen from 180.4m to 189.0m, with high-grade veins encountered from 181.8m to 183.0m and also from 187.25m to 187.7m. The host sequence is also Lander Rock Beds schist.
Drill results at a 4% C graphite cut-off were:
14MPDDHG34W1 181.40 to 183.00m 1.60m @ 4.67% C graphite
A metallurgical testwork program was carried out to determine if the graphite from Mount Peake could form a saleable concentrate (generally requiring >80% grade). Work involved compositing the individual samples and then a series of flotation/cleaner stages to produce a final concentrate of graphite at a certain size fraction.
Composites of BGC1 and G34 achieved concentrate grades of 60-70% in the initial work, while a second cleaner stage would give significantly improved final concentrate grades. Follow-up testwork was carried out on two BGC1 composites, including a higher grade composite (BGC1 HG) – with a grade of over 7% C graphite.
Both these samples returned final concentrate grades in excess of 90% graphite, indicating that saleable product could be generated from the BGC1 graphite prospect.