TORONTO (miningweekly.com) – TSX-V-listed Canada Carbon on Wednesday reported that preliminary pilot-scale flotation processing tests of hydrothermal graphite from its Miller property, in Quebec, had achieved purities greater than 99.8% carbon.

The intention with the pilot plant was to generate larger quantities of graphite flotation concentrate for downstream evaluation and provide process data to facilitate future engineering studies, including a preliminary economic assessment.

Vancouver-based Canada Carbon explained that it had submitted a large sample of lower-grade graphitic material from its Miller site to professional services firm SGS Canada to determine whether the results obtained in the June bench-scale testing of a 50 kg, higher-grade sample could be replicated with the lower-grade material.

The company was investigating the possibility of employing a bulk-mining method to include the disseminated graphite mineralisation rather than mining the graphite veins selectively. The current head grade of the bulk sample for which the preliminary results were given was about 8% carbon a ton.

The results for three product mesh sizes confirmed that the significant graphite concentrate grades obtained with the 50 kg bulk sample could be replicated on a pilot-plant scale, processing 500 kg/h.

A higher-grade sample would be submitted at a later phase of the pilot-scale flotation programme, Canada Carbon added.

"We are very encouraged that the preliminary results from the pilot-scale flotation of our lower-grade Miller hydrothermal graphite can return purity values comparable to our best bench-scale results. This indicates that high purity from flotation alone can be achieved regardless of head grade," chairperson and CEO Bruce Duncan noted.

He highlighted that expensive, secondary treatment, such as caustic bake and acid leach, might not be necessary to produce a high-purity product.

Canada Carbon holds a 100% interest in four graphite properties in Ontario and Quebec, including the past-producing Miller and Asbury mines.