Graphite mine concentrates must be upgraded with a secondary purification process in order to be used in a number of value added markets, the largest being lithium ion batteries (“LiBs”). The anode material in LiBs is graphite, either natural or synthetic, and there are no substitutes. Natural graphite, which makes up over 60 per cent of the market, must be purified to 99.95%Cg for use in LiBs and some specific impurities must be less than 50ppm. Essentially all of this purification is done in China with the wet chemical approach which is largely based on the use of hydrofluoric acid. This is difficult and/or expensive to do in the west because of environmental and workplace health and safety challenges. Thermal purification is too expensive and can still require secondary purification prior to use.
As the electric vehicle and grid storage markets expand, the demand for LiB anode material will grow exponentially and it is critical that the west develop an alternative to current graphite purification processes. Benchmark Mineral Intelligence estimates that over 300gWh of LiB manufacturing capacity will be added by 2021. This would require an additional 600,000t of flake graphite per year (current production is approximately 650,000t), and all of it has to be purified.
Gregory Bowes, Chief Executive Officer, commented that; “Northern’s patent pending purification technology represents a cost competitive, scalable and environmentally sustainable solution for the lithium ion battery industry.” He added; “This provides the Company with the opportunity to build anode material manufacturing plants, or to license the technology to other manufacturers, in parallel with the development of our Bissett Creek graphite deposit.”
The ability to purify natural graphite with chlorine is well known and has been the subject of prior patents. However, previous processes have achieved very limited commercial success because of the costs associated with high reagent consumption, long furnace retention times, batch processing and the requirement for catalysts and other chemicals. Also, high purity levels were often not achieved and the corrosive nature of chlorine at temperature caused mechanical, structural and safety problems with the furnaces. Hatch’s know how, expertise and IP have facilitated the development of a solution that addresses these issues. Initial lab and bench scale testing, and a fatal flaw analysis and scoping study, have all confirmed the viability of Northern’s process. A pilot plant test is planned to evaluate its performance on a larger scale and to refine capital and operating cost estimates.
Northern’s process can also be used as a simple means to increase the purity of flake graphite concentrates to 98 or 99% Cg for many industrial markets or to 99.95%Cg for more advanced uses.