The resource upgrade was at the Cascades deposit, one of Mahenge’s three graphite deposits. The Cascades resource increased to 52.8 million tonnes at 8.3% TGC.
Cascades contains a high grade graphite zone from surface and Black Rock is now assessing the impact of Cascade’s higher grade feed in a mining operation.
Stephen Copulos, chairman, commented: “The high grade portion from surface of 14 million tonnes at 12.1% TGC is exceptional in terms of tonnes and grade and likely strip ratio.
“We believe this will deliver industry leading operational cash costs for a project that has already demonstrated its ability to deliver a high purity product from conventional flotation circuit process.”
Black Rock owns graphite tenure in the Mahenge region, Tanzania, a country that hosts world‐class graphite mineralisation.
The Mahenge project resource is comprised of three deposits – Ulanzi, Epanko and Cascade and is the fourth largest JORC graphite resource globally.
A positive scoping study in March 2016 led into the current pre-feasibility study which is expected to be released over the coming months.
The company intends to complete a definitive feasibility study by mid-2017.
Black Rock recently achieved 99.99994% purity using a simple thermal purification process on flake graphite concentrate from Mahenge.
The Cascades JORC resource increase to 52.8 million tonnes at 8.3% TGC expands the total Mahenge Project JORC resource to 203 million tonnes at 7.8% TGC.
The Cascades JORC resource contains a higher grade zone from surface of 14 million tonnes at 12.1% TGC, which represents a 22% increase in grade compared to the Ulanzi high grade zone of 9.9% TGC.
In addition to the high grade zone, Cascades is expected to deliver an increase in free dig depth and a lower strip ratio that is likely to deliver significantly lower operating costs.
The Cascades block model is currently being integrated into the Mahenge pre-feasibility study (PFS).
Mahenge is the fourth largest JORC compliant graphite resource in the world.
This offers significant flexibility for potential development into a multi-generation mining operation.
It has potential to be mined from multiple zones at low strip ratios, high-graded to accelerate capital payback in early years and can be scaled up in future due to the large resource size.
In addition, extensive metallurgical test work indicates that high purity concentrates up to 99% TGC can be made from a straightforward flotation circuit for both oxide and primary mineralisation.
Furthermore, an extensive spherical and expandable graphite assessment program indicates that Mahenge graphite can be used to make premium products.
Mahenge has potential to deliver attractive economics due to its large size, high grades and extensive surface outcrop that offers low strip ratios and low cost mining.
The Cascade JORC resource is currently being incorporated into the PFS and is likely to deliver industry leading cash costs.
Black Rock’s ongoing focus is to develop this resource into a long life, low cost mining operation.
Shares are up 170% year to date, currently priced at $0.135.