Australia-listed Centaurus Metals has announced a significant increase in both the size and confidence levels of the mineral resource for its flagship 100%-owned Jaguar nickel sulphide project in northern Brazil.

The updated Joint Ore Reserve Committee- (Jorc-) compliant mineral resource estimate (MRE) comprises 138.2-million tonnes at 0.87% nickel for 1.20-million tonnes of contained nickel.

The global MRE at Jaguar has increased by 27% since the previous MRE announced in November 2022 and more than doubled since the company’s maiden MRE was announced in June 2020.

The MRE increase is underpinned by more than 80 000 m of new drilling from the successful 2023 Jaguar Deeps campaigns at Jaguar South and Onça Preta, along with resource development and regional exploration drilling that successfully identified mineralisation outside of the previous MRE and resulted in a new nickel sulphide discovery at the Twister prospect.

Since the June 2020 MRE, the company has established an impressive track record of defining new resources at the rate of about 170 000 t/y of contained nickel through a sustained and focused drilling programme at Jaguar, with mineralisation remaining open both at depth and locally along plunge.

Centaurus MD Darren Gordon said the robust outcomes of the August MRE update confirmed the quality and scale of the Jaguar deposit as the foundation for a large-scale, low-cost nickel sulphide development.

“The size and quality of the Jaguar nickel sulphide deposit is truly world-class. With the deposit now containing 1.2-million tonnes of nickel metal, the new MRE sets Jaguar apart as the highest-grade undeveloped nickel sulphide deposit globally with more than 1-million tonnes of contained nickel metal and unencumbered off-take rights,” he said on August 5.

Since acquiring the project in late 2019, Centaurus has safely and efficiently completed more than 185 000 m of drilling and has successfully delivered on its target to prove up more than one-million tonnes of contained nickel metal in resource.

“Delivering another major step-up in the global MRE – including a more than 30% increase in the higher-confidence measured and indicated categories to almost one-million tonnes of contained nickel – is a fantastic achievement by the entire Centaurus team and marks the culmination of a huge effort over the past four-and-a-half years.”

Importantly, the MRE update contains a high-grade component of 36.1-million tonnes at 1.49% nickel for 537 900 t of contained nickel metal, which has been estimated using a 1% nickel cut-off, with 8.3-million tonnes at 1.52% nickel found less than 100 m from surface.

“With this high-quality mineralisation so close to surface, the company now has a great opportunity to develop a new mine schedule prior to final investment decision (FID) that focuses on a higher nickel grade and higher recoveries early in the mine life to improve operating margins, reduce the capital payback period, and improve the already strong overall project economics delivered in the recently released feasibility study,” Gordon said.

Additionally, there is 21.5-million tonnes at 1.46% nickel for 313 000 t of contained nickel metal at a 1% nickel cut-off sitting below the current feasibility study pit designs, which the company believes can form the basis of a significant future underground development at Jaguar – focused on the Jaguar South and Onça Preta deposits. The underground operation would potentially bring high-grade nickel feed to the plant.

“The feasibility study demonstrated that Jaguar can deliver nickel with first quartile all-in-sustaining costs of about $3.57/lb nickel, or $4.70/lb on a payable basis, and strong environmental, social and governance credentials. The mining and underground opportunities, along with additional process opportunities, will be fully evaluated and unlocked as part of ongoing value engineering and optimisation work that is expected to further enhance the project. This work is progressing in parallel with the completion of the mining lease and installation licence approvals and the company’s strategic partnering process, targeted for completion prior to FID,” Gordon said.

At 1.2-million tonnes of contained nickel, Jaguar is one of the largest undeveloped nickel sulphide resources globally. With a resource grade of 0.87% nickel, Jaguar is the highest-grade undeveloped nickel sulphide deposit globally with more than one-million tonnes of contained nickel metal and completely unencumbered off-take rights.

The Jaguar mineralisation remains open down-dip at all deposits and locally along plunge. The company stopped drilling at Jaguar at the end of 2023, but the project continues to boast outstanding potential for future resource growth, driven by step-out and extensional drilling targeting down-hole electromagnetic conductor plates.

The company’s Jorc 2012 MRE update was completed by independent resource specialists Trepanier. This August global MRE used a total of 1 011 drill holes for a total of 246 601 m. This includes 621 diamond drill holes for 154 023 m completed by Centaurus since November 2019 and 173 Vale diamond drill holes for 58 025 m from 2006 to 2010. An additional 34 553 m of Centaurus reverse circulation drilling, comprising 217 holes, is included.

The resource development, and specifically the Jaguar Deeps drilling completed in 2023, has delivered outstanding results. The step-out drilling below the pits consistently intersected new mineralisation zones, contributing to growing the MRE significantly.

More than 187 000 t of contained nickel metal were added from the Jaguar Deeps and resource extension drilling. In-fill drilling and along-strike resource extension drilling since the last MRE update in November 2022 successfully converted additional inferred resources to measured and indicated within and around the planned feasibility study openpit limits.

The new resource delivers an estimated 138.2-million tonnes at 0.87% nickel for 1.2-million tonnes of contained nickel, with the measured and indicated component of the resource growing to 112.6-million tonnes at 0.87% nickel for 978 900 t of contained nickel, representing more than 80% of the global MRE.

Within the Jaguar global MRE, there is a significant high-grade component of 36.1-million tonnes at 1.49% nickel for 537 900 t of contained nickel metal, which has been estimated using a 1% nickel cut-off grade across the total mineral resource.

Within the high-grade MRE, around 8.3-million tonnes at 1.52% nickel for 125 400 t sits less than 100 m from surface. This demonstrates that near-surface high-grade resources are available to allow openpit operations to run at a higher nickel grade in the early years of mining to generate strong cash flows to support early capital payback.

To maintain consistency across the Jaguar MRE updates, the reasonable prospects of eventual economic extraction, as described by Jorc 2012, has been reported within a pit shell similar to that used for the November 2022 MRE.

The Jaguar MRE includes the six Jaguar deposits, two Onça deposits, along with the Tigre and Twister prospects.

The company is working towards an FID in quarter two of 2025. Completion of the mining lease and installation licence approvals and the company’s strategic partnering process are the key determining factors in the timing of the FID. The company believes it should receive the installation licence in the fourth quarter, while the mining lease grant should be delivered in quarter one of 2025.

In parallel with the permitting and strategic partnering processes over the next six to nine months, the company has kicked off the Jaguar value engineering process designed to further improve the already strong economics of the project ahead of the FID.

In terms of mining, pit optimisation runs of the new higher confidence block model boasts 30% more measured and indicated resources. Re-optimising and redesign of the openpits and associated waste containment facilities ensures a concentrate product scenario not constrained by back-end refinery metallurgical constraints.

Rescheduling the mine plan with the removal of the refinery constraints produces a mine schedule that focuses on a higher nickel grade and higher recoveries early in the mine life to improve operating margins, reduce the capital payback period, and further enhance the already strong overall project economics. Redesigning waste containment facilities minimises pre-strip waste requirements and development capital.

In terms of processing, additional metallurgical testing is intended to be undertaken to assess if the nickel grade/recovery relationship can be further improved prior to implementation, and should this be successful, the company anticipates that there may be process flowsheet design and equipment selection benefits.

Separately, early-stage testing of Jaguar and Onça Preta composite samples has shown they are amenable to ore sorting to improve grade with low nickel losses through rejection of both dilution waste and waste within the ore intersections.

Further work is required to quantify the amenability throughout the various deposits. During the implementation phase of work, the company will improve the concentrator layout to further reduce earthworks, conveyor, piping and cable runs, revise concrete and structural steel designs, and review the concentrate filtration and storage requirements for lower volume, higher-grade concentrate production.

In the underground operations, an additional 21.5-million tonnes at 1.46% nickel for 313 000 t of contained nickel metal of mineral resources, considering a 1% nickel cut-off grade, sits below the feasibility study final pit designs.

Around 75% of these resources are hosted in the Jaguar South and Onça Preta deposits. Of these mineral resources, 15.5-million tonnes at 1.5% nickel for 233 000 t of contained nickel metal is in the measured and indicated categories and will underpin a scoping study on underground operations at the Jaguar South and Onça Preta deposits to determine the potential upside of bringing high-grade nickel feed to the plant from underground ore sources. The study is planned to be completed in the fourth quarter.