Centaurus Metals (ASX: CTM) has reported “outstanding results” from a maiden drilling program at the Itapitanga nickel-cobalt project in Brazil, with high-grade mineralisation intersected at surface and initial metallurgical test work achieving high recoveries.
The 5,000m reverse circulation program, which kicked off in April, aims to test for deeper extensions of widespread nickel-cobalt mineralisation intersected in Centaurus’ hand-held auger drilling campaign earlier this year.
Seven of those auger holes finished in high‐grade nickel‐cobalt mineralisation and were subject to RC drilling to test the potential for significant depth extensions based on weathering profiles seen at nearby deposits.
Better recent nickel results include 30m at 0.92% nickel and 0.02% cobalt from 10m, 24m at 0.94% nickel and 0.08% cobalt from surface, and 19m at 1.04% nickel and 0.07% cobalt from surface.
One of the better cobalt intersections was 10m at 1.03% nickel and 0.21% cobalt from surface.
Early metallurgical testwork has continued the positive trend, with initial high-pressure acid leach (HPAL) and atmospheric leach processes achieving recoveries of nickel consistently over 98%, cobalt over 94% and scandium at 94%.
HPAL recovered the highest scandium grade at 99%, while atmospheric leach extracted up to 99% nickel and 99% cobalt.
The results demonstrate that the Itapitanga mineralisation is amenable to multiple leaching techniques and provides Centaurus with flexibility of development options for the project.
“These are great first-up metallurgical results which show that Itapitanga’s material can be successfully leached using a variety of different process routes to deliver [in excess of] 98% nickel recoveries and very high cobalt recoveries,” said Centaurus managing director Darren Gordon.
“Our drilling is coming along nicely and we expect to see further assay results over the next few weeks.”
A region rich in nickel-cobalt mineralisation
The Itapitanga discovery is located over 50 square kilometres of highly-prospective ground in Brazil’s Carajás mineral province, and south of the world‐class Jacaré nickel-cobalt project owned by Anglo American (ASX: AAL).
Jacaré hosts a global mineral resource of 307 million tonnes at 1.3% nickel and 0.13% cobalt, including a high‐grade cobalt resource of 185mt at 1.2% nickel and 0.18% cobalt – currently one of the world’s highest cobalt grades for large-tonnage nickel-cobalt deposits.
The ultramafic‐mafic intrusive complex that hosts Itapitanga and Jacaré is also home to several unpublished nickel‐cobalt resources held by Brazilian multinational Vale.
The potential of Itapitanga is highlighted by the Jacaré deposit, which is mineralised from surface down to an average depth of 50m.
Centaurus has confirmed the presence of the same nickel-cobalt mineralisation at surface at Itapitanga in multiple locations over 4.5km of strike.
RC drilling determines full width and grade
Hand-held auger drilling at Itapitanga in early 2018 demonstrated nickel‐cobalt laterite mineralisation occurring from surface, intersecting economic grades of both metals.
First-pass drilling covered a strike area of 3km in length and roughly 500m in width.
While auger drills provide a useful preliminary test of mineralisation extent, they can struggle to penetrate below a vertical depth of 10m.
Itapitanga’s deep weathering profiles occur to 50m and often up to 100m, making deeper RC drilling the only option to successfully determine the deposit’s full width and grade.
Centaurus said that first-pass RC drilling of the Northern Target has been completed, with drilling activities now focused on the Southern Target and newly-identified Western Target.
At mid-morning, Centaurus shares remained steady at A$0.0090.