AMN - MALAWI: ‘5-Nines’ purity graphite from Malingunde

Utilising a loss on ignition process to assess the suitability of mine gate graphite concentrates from its Malingunde project in Malawi, Sovereign Metals has produced ‘5-Nines’ purity graphite, which ranks amongst the highest in the world.

Downstream application test work produced ultra-high purity levels of 99.9995 weight % C from its Malingunde natural crystalline flake graphite.

The purity levels highlight the potential for product from Malingunde to enter the lithium-ion battery sector as well as high-tech and speciality markets, including the nuclear sector.

Sovereign is undertaking further test work to demonstrate the suitability of Malingunde concentrates for a range of end-user applications.

The tests were undertaken using a proprietary low-temperature thermal purification process, which reduced the required energy input and minimised the carbon dioxide footprint compared to other thermal technologies.

Low temperature refers to a process that runs at less than 2,100 degrees Celsius and is facilitated with very mild addition of chlorine gas.

Most thermal purification processes in the graphite industry are performed at temperatures of 2700-3000 degrees, which requires high energy input, adds significant costs and generates a notably higher carbon dioxide footprint.

After purification, the impurity concentration in the product was reduced to less than 5ppm.

The generally accepted maximum impurity concentration for advanced batteries is 490ppm total and 170ppm for the sum of critical element concentration.

The Malingunde purified graphite surpassed the 2ppm maximum boron concentration and 99.995% graphite thresholds, which are defined as nuclear-grade graphite purity standards by the American Society for Testing and Materials (ASTM).

Sovereign’s managing director Julian Stephens said: “Achieving 5-Nines purity in a simple and cost-efficient manner is a very important milestone in enabling entry into the emerging lithium-ion battery sector and other value-add markets.

“Entry to emerging markets, combined with sales to high-volume, high-value, traditional markets such as refractories, foundries and other industrial applications, provides Sovereign with unique product marketing optionality.

“It also provides the potential to sell Malingunde concentrates to a wide range of customers.”

Sovereign will next focus on milling and classification of the purified flake into spheronised graphite products for lithium-ion battery anodes and other high-end electrical and electrochemical applications.

This will be followed by electrochemical cell testing to examine the purified, spheronised material’s performance.

www.sovereignmetals.com.au