TORONTO (miningweekly.com) – Graphite project developer Energizer Resources this week said it had produced graphitic carbon with a purity of greater than 99.9% from a finished concentrate of the company’s flagship Molo flake graphite deposit, in Madagascar.

The product was achieved on a first-pass, single-stage hydrometallurgical purification test at SGS Canada. SGS achieved the result through an average of five repeat assays on the concentrate, conducted over two days.

The preliminary test was done to assess the ability to upgrade the Molo graphite to an ultra-pure concentrate.

Based on these exceptional results, SGS would now begin the development of a comprehensive hydrometallurgical process flow sheet over the next 60 to 90 days, while adhering to the technical guidelines of a full feasibility study.

Energizer said these studies were part of a series of ongoing metallurgical optimisation tests to enhance the capital expenditures and operating expenditures presented in the company’s preliminary economic assessment (PEA) study from January.

“This is highly significant and reconfirms, as demonstrated from the mineralogical results in our completed PEA study, the exceptional quality of our graphite. Molo is situated in an extremely rare and unique geological setting which has resulted in our flake graphite being both very high in purity and in quality,” president and COO Craig Scherba said in a recent statement.

The graphite concentrate used in the first pass hydrometallurgical purification testing consisted of a flotation concentrate that was generated in a single-cleaner flotation test without optimised conditions. The purification process employed a conventional leach technology and demonstrated exceptional purities.

In June, SGS started Phase 1 of the Molo pilot plant process. This comprised a systematic series of tests to finalise an optimised process flow sheet for the Molo deposit, focusing on reducing capital and operating expenses of the future mine, while maximising graphite flake size fractions, concentrate grade, and graphite recovery.

The company expected to release the results of Phase 1 to the market within the next 30 days, and expected the results to have a significant positive impact on the company’s PEA study, which reported a net present value of $421-million at a 10% discount rate, an internal rate of return of 48%, and a payback of three years.

A carbon speciation of the two composites provided to SGS, which were used to generate the concentrate, revealed that total organic carbon and carbonate carbon concentrations were below the analytical detection limits of 0.05%.

These preliminary results suggested that, essentially, all carbon contained in the samples was present in the form of graphitic carbon.

To Energizer, this further confirmed that the flake graphite from Molo is of the highest quality.

“The ability to produce a natural-flake-graphite product, with the highest purities possible, using low-cost, standard processing techniques will allow Energizer to target all markets using value-added graphite applications,” the company said.

According to industry experts, only natural flake graphite has the necessary attributes that allow it to be used across all applications where natural graphite can be used. The three largest demand markets for high-purity natural flake graphite today and in future were refractories, battery and energy storage, and specialty graphite foils.

Natural flake graphite is the choice for many refractory applications owing to its particle shape and size. Neither synthetic nor amorphous graphite could be used to produce graphite foils, a main component in smart phones, consumer electronics, solar panels, laptops and all flat panel television and computer monitors. Flake graphite is the main form of natural graphite that competes directly with synthetic graphite in producing battery anode material.

The PEA on the project envisaged a conventional openpit mining method using trucks and loaders, with a capacity of 1.17-million tonnes a year of ore at 92% availability, with an average head grade of 8.5%.

The processing would entail three-stage crushing followed by a primary milling and flotation separation circuit. The resultant flake graphite concentrate would be thickened, dried, separated into various flake sizes, packaged and stored before shipment.

The final residue generated by the flotation process would generate a clean, nonacidic tailing.

The concentrate production is estimated at an average of 84 000 t/y of graphite concentrate, with an average specification of 92%.