With an updated mineral resource estimate (MRE), rutile and graphite miner Sovereign Metals reports that its Malawi-based Kasiya deposit has become the largest in the world with 1.8-billion tonnes of indicated and inferred resource at 1.01% rutile, which is more than double the contained rutile as its nearest rutile peer, Sierra Rutile.
In addition, the graphite by-product detailed in the MRE at Kasiya places it as the second-largest flake graphite deposit in the world, the company says.
Natural rutile is a scarce commodity, with no other known large, rutile-dominant deposits being discovered in over half a century, Sovereign states.
The miner notes that current sources of natural rutile are in decline as several operations’ reserves are depleting concurrently with declining ore grades. These include Iluka Resources’ Sierra Leone-based Sierra Rutile mine and Base Resources’ Kenya-based Kwale operation.
There are limited new deposits forecast to come online, meaning supplies of natural rutile are likely to remain in “extreme structural deficit”, says Sovereign.
The latest MRE reveals broad zones of very high-grade rutile which occur contiguously across a very large area of over 180 km2. Rutile mineralisation lies in laterally extensive, near-surface, flat blanket-style bodies in areas where the weathering profile is preserved and not significantly eroded.
Overall, the new MRE shows a number of new large, but generally-discrete high-grade rutile zones, particularly in the southern parts and eastern parts of the resource area. The discovery and delineation of these new high-grade mineralised zones has been the dominant factor in the tripling of the resource base.
A total of 662-million tonnes, 37% of the total MRE, reports to the indicated category at a grade of 1.05% rutile and 1.43% total graphitic carbon, with a recovered grade of 1.73% recovered rutile and recovered graphite.
The Kasiya deposit is expansive with high-grade rutile mineralisation commonly grading between 1.2% and 2% in the top 3 m to 5 m from surface. Moderate grade mineralisation generally grades between 0.5% to 1.2% of rutile and commonly extends from 5 m to end of hole where it remains open at depths of greater than 10 m in numerous drill-defined, north to north-east striking zones.
Sovereign MD Dr Julian Stephens says discovering the largest natural rutile deposit in just two years since initial identification is a “remarkable achievement”.
“The step-change in scale will now allow us to examine potentially higher-grade throughput, increased production levels and a longer mine life in the upcoming scoping study update,” he adds.
Stephens notes that Sovereign is targeting a large-scale, low-carbon-footprint and environmentally-sustainable natural rutile and graphite operation, which will also positively impact the environmental footprint of titanium pigment and other industries, and provide a significant contribution to the economy of Malawi.
Going forward, Sovereign is rapidly continuing its work programmes, starting with an updated scoping study targeted for completion in the second quarter of this year to build on the 2021 scoping study.
This will be driven by the significant increase in the MRE, providing the opportunity to assess higher grade throughput, increased production rates and longer mine life.
The miner is also starting initial prefeasibility study (PFS) activities, including metallurgical programmes and hydrogeological studies. Other study elements will commence shortly with major technical consultant site visits this month. The PFS is targeted for completion in early 2023.
In addition, Sovereign is planning to continue drilling to test the depth and lateral extensions at Kasiya. These include mobilising an air-core drilling rig to Kasiya in mid-May, with a planned 300-hole, 10 000-m programme with the aim of deepening the better high-grade areas in order to add to the next MRE upgrade.
Also, the miner aims to continue infill and step-out hand-auger drilling to expand the overall mineralised footprint with drill teams mobilising this month.
Sovereign is also continuing to work with potential offtakers and strategic partners in the pigment, welding and titanium metal industries to secure further agreements regarding future offtakes.
Also planned for the near term are initial environmental and social impact assessment activities, including environmental and community baseline surveys. These will inform the upcoming PFS, with continued focus on developing low carbon-footprint operations taking advantage of renewable power supply and soft-friable saprolite mineralisation to produce natural rutile and graphite with far lower global warming potential than alternative products.