The test work is part of optimisation work being conducted at Ulanzi, which is a part of Mahenge.
Flake sizes range from -25μm to +500μm and 86% of the size range achieved a 99.1% total graphitic carbon purity.
Spherical graphite test work is underway in Europe to determine the suitability of Mahenge graphite for battery applications with results expected in late July.
Steven Tambanis, managing director, commented:
"Achieving over 99% purities across the size range is an exceptional result for the project and we look forward to applying our processing improvements to new metallurgical samples expected from site next month.
"The ability to produce graphite concentrates at high levels of purity enhances our potential to sell into the premium flake graphite market.
"This importantly allows Black Rock Mining to brand and market its flake graphite product being processed acid free."
Metallurgical test work details
A 99.1% concentrate purity was achieved through a relatively simple adjustment to the flowsheet, which offers more optimisation potential.
The entire +75 to +500 micron portion of flake graphite is now achieving 99.1% purity.
The metallurgical program is expected to continue for the next four to six months, in parallel with the pre feasibility and definitive feasibility studies.
More bulk samples will be sent from Mahenge over the coming months to be comprehensively tested.
The optimisation work being conducted at Mahenge is suggesting the flake graphite is able to be easily processed into a high purity concentrate for sale into premium grade markets.
The processing is being achieved through a conventional, acid-free flotation circuit with further optimisation potential.
The share price is up 55% over the past 3 months, currently trading at $0.07, higher than any close price in 2016.
Earlier this month, Perth broker Patersons initiated coverage with a valuation of $0.12 per share and Speculative Buy rating.
The scoping study released in March 2016 forecast the project to have a net present value of US$285.7 million and an internal rate of return of 62%.
Proactive Investors Australia is the market leader in producing news, articles and research reports on ASX emerging companies with distribution in Australia, UK, North America and Hong Kong / China.