ASX- and Aim-listed Sovereign has reported “excellent” results from graphite testwork completed at multiple independent laboratories in Australia, Canada and South Africa using a conventional flowsheet that was consistent across all laboratories.

The company believes this confirms its ability to produce a high-quality graphite concentrate.

Graphite flotation and cleaning testwork was conducted on graphite circuit feed from Sovereign’s Kasiya rutile/graphite project at four different laboratories, which all successfully produced high-grade graphite concentrate between 94.9% and 97.8% total graphitic carbon (TGC) at high flotation recoveries of between 91.2% and 97.2%.

“Our ability to upgrade Kasiya ore at 1.4% graphite to a 55% rougher concentrate without any crushing or milling highlights more of the unique qualities of Kasiya. There are very limited other graphite projects with these characteristics. The pilot-scale results also confirm that Kasiya produces high-grade concentrates with very low sulphur levels at high recoveries.

“Simply put, Kasiya will be a standout producer of high-quality graphite concentrate at industry-low operating costs,” Sovereign MD Frank Eagar said on May 8.

The graphite circuit feed provided to the various laboratories was produced at the company’s existing laboratory facility in Lilongwe, Malawi, where it was screened and separated over a wet shaking table.

The graphite feed grades of 3.5% to 4% TGC to the graphite circuit are significantly higher than the mineral resource grade of 1.44%, highlighting the about 2.4- to 2.8-fold upgrading of graphite grades when run-of-mine (RoM) ore passes through the front-end rutile gravity separation circuit.

This demonstrates the ease of separating the rutile heavy mineral and graphite streams from the front end of the Kasiya prefeasibility study process flowsheet.

Subsequently, the two product streams pass into distinct, industry-standard, final product flowsheets. This further highlights the commercial benefits of having both rutile and graphite mineralisation co-existent in the same soft saprolite-hosted orebody.

The first stage of upgrading the graphite feed, rougher flotation, achieved very high rejection of more than 90% of waste materials to rougher tails, producing a rougher concentrate with more than 55% TGC and high recoveries of between 94% and 98% in laboratory scale testing consistently across all four laboratories.

Upgrading the graphite feed at very high recoveries and rejection of nongraphitic minerals without RoM milling supports low-cost graphite production.

The rougher concentrate was further upgraded through laboratory scale flotation, cleaning and polishing stages, producing high-grade concentrates at high graphite circuit recoveries.

Sovereign has reported that the Kasiya concentrates have very low levels of sulphur, iron, silicon and aluminium. Sulphur in particular can be difficult to remove in the purification processes required to produce anode materials.

Benchmarked against the Chinese standard, since China dominates the supply of graphite for battery anodes, Sovereign believes this could potentially lead to significant commercial advantages during purification and Kasiya’s potential as a long-term secure source of graphite outside of China.

Kasiya concentrate has been sent for downstream testwork at graphite consultancy ProGraphite to produce and characterise coated spheronised purified graphite (CSPG) active anode material for lithium-ion batteries.

ProGraphite is conducting shaping, purification, and coating testwork to produce CSPG and evaluate the electrochemical performance of Kasiya CSPG.

Sovereign said this would provide baseline data for further optimisation and engagement with offtakers. Initial outcomes of this testwork are expected to be released in the coming weeks, the company said.