This week's deal with Chinese trading house Taihe Soar stands to be one of the largest, de Vries says, with the potential for up to 100,000tpa by year three, starting at 37,500tpa in year one and rising to 80,000tpa in year two.
Taihe Soar is also important in that it opens up a third sales channel using a distributor model to access smaller volume consumers that would normally not have access to international markets.
It follows deals for up to 90,000tpa with Heilongjiang Bohao and 15,000tpa with Qingdao Fujin that were announced in October, and covers 100% of the output of the planned first and second modules.
Pricing terms, to be set quarterly with reference to market price for flake size and concentrate grade, will be negotiated over the next 12 months.
de Vries said the arrangements showed market demand for Mahenge output would be strong, with the company havnig supplied concentrate samples from its 90t pilot plant.
Now it has sold production for the first two modules it will focus on module three and working on a fourth self-funding module to take proposed production to over 300,000tpa.
It has also commenced work to optimise its mine plan by compressing its development schedule.
The company remains confident it can secure access to development funding in time to meet its project schedule.
Black Rock believes it has a world-class project that can be in production by mid-2020 for the US$115 million stage one.
Stages two and three will cost $69.5 million and $84.2 million respectively - although Black Rock is working with strategic partner Yantai Jinyuan to reduce those figures by procuring assets from China.
Black Rock's DFS describes Mahenge as a "best in class" graphite project with the fourth largest JORC compliant contained graphite resource in the world with resources of 212 million tonnes grading 7.8% total graphitic carbon. Reserves are 70Mt at 8.5% TGC and will support 23 years of operations.