de Vries previously held the role on an interim basis, and has served as the company's chief operating officer.
de Vries commented on the appointment:
"Very rarely in your career do you get the opportunity to step in on the ground floor, and develop a world class project like the Mahenge Graphite project in Tanzania.
"Ultimately, Mahenge will play an import role in delivering benefits for our investors, our Tanzanian stakeholders and through the emerging battery thematic, a better planet."
Black Rock wholly-owns the Mahenge project, which is the is the fourth largest JORC compliant contained graphite resource in the World.