Clean energy minerals explorer and developer NGX has used flowsheet optimisation test work to produce a concentrate grading more than 98% total graphitic content (TGC) from its Malingunde natural graphite project in Malawi.
Feedstock for the tests was generated from a 50-tonne ore processing pilot plant program conducted at SGS Canada by the project’s previous owner, which achieved a concentrate grade of 93.9% TGC.
NGX’s work delivered a 4% boost to that average grade, reaching between 97.1% and 97.9% TGC at recoveries of more than 99% with minimal graphite loss.
Downstream advantages
Assays on the size fractions of the upgraded concentrate displayed very high grades, with samples below 38 microns (which can be difficult to upgrade) achieving a TGC grade of more than 96%.
NGX said the higher-purity concentrate offers a significant advantage in downstream processing, with the potential for lower reagent consumption and environmental benefits to purify the material.
It is believed to be suitable as feedstock to produce active anode material used in the manufacture of lithium-ion batteries.
NGX’s program concluded that weathered, saprolite-hosted ore at Malingunde is amenable to significant upgrades, reducing the extent of downstream processing required to achieve battery-quality material.
Customer assessment
A 100-kilogram sample of the upgraded product at -150 micron fraction has been despatched to a Tier 1 anode customer for assessment and will be used by NGX for further downstream testing as part of its ongoing qualification work.
A remaining 155kg sample from the optimisation program will be used by NGX for a vertically integrated ore-to-anode materials development program.
The data will be used to further optimise the concentrate and provide initial “A” samples for evaluation by additional customers.
Efficient upgrade
NGX director Peter Fox said the company was pleased with the outcome of the concentrate upgrade program.
“We are particularly encouraged by how it has upgraded so efficiently with simple amendments to the flowsheet,” he said.
“In the current market, with a benchmark of 94% TGC, the cost efficiency and environmental benefits of producing concentrate at 98% TGC purity are significant and present a compelling opportunity for industry stakeholders and downstream end-users to take notice.”
