ANSTO testing confirms Red Metal’s Phase 1 test work on Sybella rare earths mineralisation
This lends confidence to the belief the project in northwest Queensland is host to a unique heap leachable source of REOs
Low levels of acid consumption expected to result in lower processing costs
Upcoming Phase 2 test work to provide optimised data necessary to firm-up metallurgical characteristics
Special Report: Metallurgical test work which indicated Red Metal’s Sybella rare earths project in Queensland is amenable to heap leach processing has been given a massive tick by industry specialists ANSTO Minerals.
Sybella is 20km southwest of Mt Isa and was proven as a new rare earth oxide (REO) discovery in August 2023 by proof-of-concept drilling which returned significant intersections from a unique, enriched granite intrusion.
Holes drilled across the granite at the Boundary Fence traverse highlighted the grade and substantial width of the new find, which is interpreted to host two mineralised zones each about 1,000m wide, while widely spaced holes at the Donkey Dam profile 4km to the north also highlighted similar long intercepts of REO mineralisation.
Notably for Red Metal (ASX:RDM), valuable magnet rare earths such as neodymium, praseodymium, dysprosium and terbium make up a significant part of the overall REO content.
Phase 1 heap leach testing carried out by the company achieved strong REO extraction with low levels of impurities on coarse, non-pulverised RC drill chip samples using low levels of sulphuric acid at ambient temperatures, proving that rare earths can be produced from the Sybella mineralisation using simple processing options.
Costs are also likely to be easily controlled due to the low acid levels, the use of ambient temperatures (alleviating the need for heating) and avoiding the need for extensive crushing.
Data from the testing also indicates that REO extractions can be improved by optimising the process, adding substance to the company’s declaration that Sybella has scope for large tonnages of “weak-acid soluble REO mineralisation hosted in low-acid consuming granite rock”.
ANSTO validation a confidence booster
RDM has now flagged that leach tests carried out by ANSTO Minerals – one of the world’s leading rare earth metallurgical specialists – on the same RC chip samples using a similar ‘simple’ bottle roll leach methodology has returned similar strong REO extractions and low acid consumptions as the earlier tests conducted by Core Resources.
It added that slight differences in results between the two set of tests would be addressed during planned Phase 2 leach test work, which will use coarsely crushed drill core.
This work will evaluate the leach responses for a range of size fractions under varying pH conditions and over extended residence times, with the aim of providing more optimised data for an early-stage mining study.
Other Phase 2 work will include comminution tests and additional processing of pregnant leach solution (PLS) to recover the rare earths.
Speaking to Stockhead, RDM managing director Rob Rutherford said the company considered it diligent to have its Phase 1 metallurgical test work validated by ANSTO Minerals given it was breaking new ground with the Sybella discovery.
“Our early breakthrough results back-up with ANSTO’s validation should give shareholders and new investors confidence that Sybella is in a class of its own and has the potential to be a unique heap leachable source of rare earth oxide minerals offering highly competitive capital and operating costs,” Rutherford says.
“It is expected the current Phase 2 metallurgical work on the crushed drill core will provide the optimised data necessary to firm-up the metallurgical characteristics and processing options needed to define what potentially economic ore may look like.
“With this assessment, we can finetune our step-out drilling – which is set to begin in May – focusing first on the most economic portions of the large 12km by 3km rare earth enriched granite.”
Land access preparations ahead of a regional step-out drill program are progressing. Drilling is anticipated to begin early May 2024.
This article was developed in collaboration with Red Metal, a Stockhead advertiser at the time of publishing.
This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.
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