Australian company discovers graphite in Ghana
Ghana is a country well-known to be rich in precious minerals. The country is the leading producer of gold in Africa. It has deposits of bauxite, diamond, manganese and recently lithium has also been discovered in commercial quantities.
An Australian company, described by the Australian media as a junior multi-commodity explorer, Castle Minerals has announced it is conducting a survey to define the extent of graphite deposits it has found in Ghana.
According to Castle Minerals, it started graphite exploration in Kambale, a suburb of Wa, the Upper West regional capital in 2012.
It indicates on its website that a historic graphite occurrence about 5km west of Wa was first noted by Russian geologists whilst prospecting for manganese in the 1960’s.
According to Castle, it located the historic trenches and completed mapping, RAB, aircore and RC drilling during the first half of 2012.
In July 2012 it announced a maiden resource estimate for its Kambale Graphite of 14.4mt @ 7.2% C (graphitic carbon) for 1.03mt contained graphite (Inferred Resource).
“Flotation testwork was conducted on samples of fresh and weathered graphitic schist from the Kambale deposit. Microscopic examination of some flotation concentrates indicated that the graphite flakes were up to 250 microns long,” the company says.
Australian media reports that the company has initiated a high-resolution ground based horizontal loop electromagnetic geophysical survey to assist in defining the mineralisation extents of the graphite deposit. The reports indicate that the geophysical dataset is expected to guide further targeting including finding specific areas likely to achieve the best quality fresh rock samples for upcoming diamond drilling.
“The geophysical survey was launched shortly after Castle received positive graphite concentrate grades from preliminary metallurgical test work at Kambale. The study was conducted on near-surface, weathered graphitic schists in 2021 that achieved fine flake graphite concentrate grades of up to 96.4 per cent and recoveries of 88 per cent,” The West Australian reported.
The publication stated further that the Kambale graphite project is Ghana’s and indeed West Africa’s only known graphite deposit of decent scale.
According to Castle Minerals, in order to achieve a high grade of product from the samples supplied, a grind size below 75 microns is recommended. The softness and smearing effect of the graphite on the gangue minerals, drives the need to take small size reduction steps followed by multistage flotation. The sample supplied for testing was RC chips and the RC drilling process itself may increase the smearing effect of graphite over the gangue minerals and any further testwork should be carried out on diamond drill core.
It adds that the testwork results from this initial study have shown that an upgrade to just over 50 per cent graphite can be achieved in 1-2 stages of flotation. Further test work would be needed to determine if additional grind-flotation and/or gravity stages could increase the grade to produce a high grade graphite product, the company notes, on its website.
By Emmanuel K. Dogbevi