Red Metal is now eagerly awaiting the results from pH optimisation bottle-roll leach tests completed on composite samples from this campaign, due in March, to determine the optimal low-acid solution to use in its next stage column leach testwork.
The vitally important column leach testing is the company’s current priority. It plans to replicate the outcome from a heap leaching process, which can often take months to maximise the extraction of metal from the ore. Heap leaching is expected to be used for processing at scale if the project moves into a mining operation.
Results from column leach testing can take a similar duration and are costly to achieve, so it is important to have nailed down the correct low-acid solution to optimise results straight off the bat.
Plans are underway to obtain enough ore for the column leach testing by drilling large diameter diamond core holes.
The company is aiming to have the column leach testwork completed by mid-year.
The infill program was cut short due to a large bush fire on the project area near the end of the field season. Three separate lines of drilling were completed across the eastern Kary zone.
Management believes drill spacing within the three completed lines is sufficient to qualify it for an indicated resource status. It says the consistency of the mineralisation warrants drilling the remaining portion of the area it was unable to access due to the fire.
Red Metals plans to use its combined drill results in its calculations to upgrade the overall zone to the indicated category.
Red Metal managing director Rob Rutherford said: “Confirming the continuity of the wide zones of higher-grade rare earth mineralisation at Sybella is an essential step towards realising its potential for bulk tonnage heap leach mining. Repeating our positive early-stage metallurgical results with pH optimisation tests on composited samples representative of a larger area is the next key step.”
The company previously conducted intermittent bottle-roll tests on reverse circulation drill chips from weathered and fresh granite samples, which showed the ore to be ideal for a heap leach processing operation.
It last year engaged metallurgical specialists ANSTO Minerals to validate its breakthrough leach results using chip samples from Sybella.
The company says ANSTO’s supplementary findings back up its phase one testwork – completed by Core Resources and revealed early in 2024 – that showed high recoveries and low impurities using low levels of acid consumption for both valuable magnet and heavy rare earth oxides.
Promising early metallurgical testing indicates that 21 per cent of the project’s mineral basket value comes from high-demand heavy rare earth elements, such as dysprosium and terbium.
Red Metal has tabled a massive 4.8-billion-tonne rare earths resource for the Sybella project at 302ppm neodymium-praseodymium and 28ppm dysprosium-terbium, using a 200ppm neodymium-praseodymium cut-off grade.
By increasing the cut-off grade to 360ppm neodymium-praseodymium , the resource was estimated at 209 million tonnes grading 377ppm neodymium-praseodymium and 34ppm dysprosium-terbium.
Management says the bulk of the resource material starts at surface and remains open at depths below 100m, which provides an option for early, low-cost mining.
The company believes abundant granite-hosted soft ore in its ground provides the Sybella project with a compelling edge and offers simple crushing and processing options.
The Sybella deposit sits on 12km-by-3km granite-pervasive ground with ore susceptible to simple low-temperature processing, pointing to a likelihood of a low-capex operation.
If Red Metal can keep expanding the size of the prize and get the processing side right, the sky could well be the limit for Sybella.
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