TORONTO (miningweekly.com) – Project developer Northern Graphite has developed a proprietary process for purifying concentrates from its Bissett Creek project and has consistently and economically achieved graphite purity levels of 99.95% and higher in independent laboratory and bench scale testing.

High-purity graphite is required for many value-added and rapidly growing graphite applications, including lithium-ion batteries.

The company on Monday said that, for the past two years, it had been working with research laboratories and testing facilities in Canada and the US, and equipment manufacturers in the US and Japan, to develop an alternative to the wet chemical purification process used in China and the thermal process commonly used elsewhere.

Northern Graphite has completed bulk-sample and pilot-plant testing that provided a representative sample of the concentrates that would be produced from the commercial process.

Extensive laboratory-scale testing on these concentrates resulted in a process that successfully purified micronised, spherical and flake graphite to 99.95%+ levels.

This process was subsequently tested in bench-scale models of commercial equipment and spherical graphite, with 99.95%+ purity produced consistently. Flake graphite purities as high as 99.9% were achieved at the bench scale and further optimisation work was ongoing.

Northern Graphite worked with Kingston Process Metallurgy, Hazen Research, Hosokawa Micron Powder Systems, Harper International, Nara Machinery, AAAmachine Japan and the National Research Council of Canada in perfecting the purification process.

"Our goal is to provide customers with a secure source of competitively priced spherical graphite that is produced in an environmentally acceptable manner. Our consultants estimate that purification costs will be less than $1 000/t,” Northern Graphite CEO Gregory Bowes said.

The wet chemical process uses hydrofluoric and hydrochloric acid and is low-cost if the waste products are not neutralised. This was generally the case in China and created significant environmental issues in terms of soil and water pollution.

The chemical process was also used to purify spherical graphite, the product used in lithium-ion batteries. This approach was not sustainable in the long term, as demand for these batteries was expected to grow rapidly with the increased adoption of ‘green’ hybrid and all electric vehicles, the company said.

The thermal purification process is expensive owing to the capital and operating costs incurred in furnaces needing to achieve temperatures of 2 400 °C plus.

RISING MARKET

The total worldwide graphite market is estimated at $13-billion dollars a year.

The natural graphite market, consisting of both flake and amorphous graphite, makes up less than $1-billion of the total. The balance of about $12-billion is synthetic graphite that consists of graphite electrodes for electric arc furnaces, carbon fibres for composite materials and speciality blocks and pieces for many different applications.

These three types of synthetic graphite were made from special raw materials such as petroleum coke and do not use any type of natural graphite. Natural graphite does not have the properties for use in producing or replacing synthetic graphite, regardless of purity.

Bowes said there were smaller, crossover markets where micronised, purified natural graphite did compete with powder or granular synthetic graphite, including spherical graphite for lithium-ion batteries.

“This is the largest and fastest-growing part of the ‘high-purity’ powdered graphite market. The spherical natural graphite market is estimated at 25 000 t/y, which requires 75 000 t of flake graphite to make, because yields are only 33%. The specialty powder synthetic graphite market is also estimated at 25 000 t/y,” the company said in a statement.

Only natural flake graphite that can be economically rounded and purified to 99.95%+ can be used to make spherical graphite. Spherical graphite manufactured from natural graphite has certain performance advantages and is much lower cost than the powdered synthetic graphite specially produced for lithium-ion batteries.

Prices for high-purity natural graphite are currently in the $3 000/t to $4 000/t range and up to $10 000/t with the addition of special coatings needed for use in lithium-ion batteries.

Northern Graphite has already produced spherical graphite and successfully tested it in batteries. The company was currently optimising the process based on feedback from potential customers and partners and is working on its own proprietary coating process.

TSX-V-listed Northern Graphite’s Bissett Creek project was given the go-ahead in August, after the Ministry of Northern Development and Mines approved the project’s mine closure plan and granted a mining lease.