Red Metal has delivered a boost to its Sybella rare earths discovery in Queensland, with metallurgical testwork enhancing the prospects of a low-cost and low-capital heap leach processing operation.
Management believes the results could pave the way for a process route that lifts revenue and lowers processing costs in a future mine at the project that is stationed just 20km from the infrastructure-rich town of Mount Isa.
The company’s latest results come from an ongoing phase two metallurgical campaign that consisted of leach testwork and comminution studies designed to generate optimised data for an early-stage mining study. In other words, management is looking to nail down the most economically effective method for processing the rare earths at the project.
According to Red Metal, Sybella shows unique metallurgical characteristics and it could represent a new deposit style for Australia – and possibly the world – with rare earths mineralisation hosted in both weathered and fresh granite across a vast 12km-by-3km area.
Results from the phase two campaign suggest that coarser heap leach crush sizes can generate high rare earths recoveries – and that may translate into greater revenue in a future mining operation. Meanwhile, less contaminant liberation and lowered acid consumption could also reduce processing costs.
More specifically, the testwork confirmed that strong rare earths extraction can be accomplished by using low levels of ambient-temperature sulphuric acid on coarse fractions of both weathered and fresh granite during increased residence times.
The company believes lowering the acid strength and increasing the residence time has vastly improved the reduction of iron and aluminium contaminants, while also significantly decreasing the acid consumption rate.
Red Metal managing director Rob Rutherford said: “The Company has reasonable expectation that our ongoing studies will confirm a process route that optimises REO recovery (increases revenue), but reduces the acid consumption rate and ensures that impurities in the final product can be satisfactorily minimised (lowering processing costs). It is also now working rapidly towards outlining ore resources.”
Management noted that metallurgical testing of fresh granite has triggered a “breakthrough” leach result that creates the potential for large-tonnage extraction of rare earths found beneath the weathered zone. It added that coarsely-crushed granite – both weathered and fresh – boasts characteristics suitable for generating competitive capital and operating costs for mining and crushing at the project.
More broadly, the testwork at Sybella showed that different heap leach strategies for weathered and fresh granite can achieve strong outcomes. It includes extraction rates of up to 92 per cent from weathered granite for two elements playing a starring role in the burgeoning electric vehicle (EV) market – neodymium and praseodymium.
Results from the phase two campaign build on the company’s initial metallurgical testwork that identified an opportunity for simple and low-cost rare earths processing involving heap leach methods. It prompted Red Metal to launch an ongoing step-out drilling campaign through an 8km-by-3km area at Sybella.
More than 70 holes have been drilled to date.
Further metallurgical works are also ticking along, with Red Metal conducting impurity removal trials designed to produce a premium-mix rare earths carbonate product. Results from the tests are expected in the coming weeks.
Preparations for follow-on column leach testwork are also underway as the company looks to further improve rare earths recoveries, reduce acid consumption and lower contaminants in its processing methods at Sybella as a maiden resource estimate draws nearer.
Metallurgical processing is a crucial component of any mining operation, especially for rare earths projects where highly-complex metallurgy can often play a detrimental role in economic feasibility.
But Red Metal appears to be standing on the podium in its efforts to move Sybella towards production, with its testwork so far hinting that the project is well on its way to overcoming such metallurgical hurdles.
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By Bart Bogacz
