Evolution Energy Minerals Ltd (ASX:EV1) says thermal purification testing of graphite fines from the Chilalo Graphite Project in Tanzania has returned an exceptional, industry-leading purity level of 99.9995% C.
The results confirm that purified Chilalo graphite is a premium precursor material to producing spherical graphite for battery anode applications and nuclear-grade graphite, which sells for about US$30,000 per tonne.
This test-work, performed in partnership with Evolution’s US-based technology partner using thermal purification and proprietary coating technologies, had earlier confirmed that Chilalo’s graphite contains very low concentrations of impurities molybdenum and boron.
Further results are expected over the coming weeks as the test-work to evaluate the amenability of Chilalo graphite fines for producing coated battery anode materials continues.
“Impurities on flake surface”
Evolution Energy Minerals managing director Phil Hoskins said: “The successful purification results indicate that Chilalo graphite is highly amenable to a range of value-added applications in advanced battery systems, including lithium-ion battery anodes.
“Our graphite was shown to be easily refined due to the impurities being situated predominantly on the flake surface, hence the ease with which they can be removed.
“We are excited to have achieved industry-leading purity levels of 99.9995 wt.% C using thermal purification, as opposed to most conventional graphite purification technologies that use toxic leaching agents, such as HF acid.
“Evolution is committed to producing sustainable battery anode materials and adopting a thermal purification process using renewable electric power, which creates a greener and more sustainable product for battery supply chains of the future.”
“Green” mine
Evolution is positioning itself to produce the world’s most green and sustainable battery anode materials by combining environmentally-friendly thermal purification technology with the desire to develop Chilalo as the world’s first net-zero carbon graphite mine.
The use of thermal purification will enable a lower carbon footprint for Chilalo’s battery anode material supply chain as well as developing a competitive battery anode material supply chain by keeping costs low.
At a power cost of US$0.05/kWh, the cost of thermal purification using Evolution’s process is about US$500 per tonne – notably lower than the US$700 per tonne cost of refining graphite using the traditional Asian flowsheets to produce a 99.9 to 99.95 wt.% C product.
All impurities removed
Microscopy image of Chilalo flake of concentrate purity.
Mineral impurities in Chilalo sit predominantly on the graphite surface, making it much easier to remove than those in between graphite layers.
The thermal purification process successfully removed all the elements harmful for use in advanced battery systems such as premium-performance lithium-ion and alkaline batteries.
Prior to purification, the Chilalo graphite concentrate contained 4.3% ash – a collection of mineral impurities, typically in the form of iron, aluminium and silicon oxides.
After thermal purification, the total quantity of mineral impurities was measured to be 5 parts per million (ppm), with iron measuring 0.97 ppm, nickel 0.64 ppm, aluminium 0.73 ppm, chromium 0.71 ppm, molybdenum 0.1 ppm, and silicon 0.66 ppm.
Super-premium grades of graphite for lithium-ion batteries must maintain iron levels below 10 ppm.
Nuclear application
The primary demand driver for ultra-high-purity graphite is nuclear applications, specifically Pebble Bed Modular Reactors, which consume about 60,000 tonnes of purified graphite per annum and sells for approximately US$30,000 per tonne.
Whilst this was not Evolution’s target market when the commercial verification program commenced, Evolution said it now planned to engage in qualifications of ultra-high purity Chilalo graphite with various customers in the nuclear industry, including government agencies.
Next steps
The company also plans to formalise a technology partnership with the US partner that will allow it to utilise advanced technologies and facilities to, among other things, toll treat the Chilalo graphite for product qualification initiatives.
Evolution expects to shortly release the results of test-work on the production of coated spherical graphite using thermally-purified Chilalo graphite.
Subject to the results of that work, Evolution expects to undertake a feasibility study on the production of coated battery anode materials and other advanced battery products.