Rimfire Pacific Mining: Murga’s Low-Iron Scandium Points to a Cheaper Route
- Noel Ong
- 2 days ago
- 10 min read
First metallurgical tests suggest Murga’s low-iron scandium could be leached at atmospheric pressure — a cheaper, simpler alternative to the HPAL route its neighbours face.
Rimfire Pacific Mining Ltd (ASX: RIM) has released the first metallurgical results from its Murga Scandium Deposit situated within the Fifield district of central New South Wales, Australia.
The early read is the kind that matters in scandium: the rock appears to be cheap to process. Initial bottle-roll tests suggest that if the recovery rate seen over 14 days holds across a commercial timeframe, scandium recoveries of 60–90% could potentially be achieved.
Importantly, this is at atmospheric pressure, rather than via the capital-hungry high-pressure route Murga’s neighbours are contemplating (Figure 1).
For a company whose stated goal is to build “a globally significant scandium resource inventory” at Fifield, this is the first hint that the inventory might also be economically extractable. It is early, and Rimfire says so plainly - but the direction is encouraging.
▸ At a Glance
Item | Description |
Company | Rimfire Pacific Mining Limited (ASX: RIM) — a critical-minerals explorer |
Focus | Scandium — the Fifield District, central NSW (“Australia’s scandium epicentre”), ~70km NW of Parkes |
The deposit | Murga Scandium Deposit — Inferred Mineral Resource of 11,900t (11.9Kt) scandium oxide |
The news | First-ever metallurgical tests on Murga material — a 14-day bottle-roll leach at atmospheric pressure |
The result | Recovery rate over 14 days indicates 60–90% scandium recovery may be achievable over a commercial timeframe (indicative, not definitive) |
Why it matters | Murga’s low iron content (~16% Fe) raises the prospect of atmospheric heap/vat leaching — far less capital-intensive than High Pressure Acid Leach (HPAL) |
Point of difference | Neighbouring deposits (Syerston, Flemington, Burra) are higher-iron (Burra ~34% Fe) and are contemplating HPAL; low iron is Murga’s key differentiator |
Resource inventory | More than 16Kt Sc₂O₃ in total across Melrose (1.1Kt), Currajong (3.1Kt) and Murga (11.9Kt) |
What’s next | Two longer Stage 2 bottle-roll tests (160–180 days) now underway; a possible column/vat leach test; and an agitated tank leach test as an alternative pathway |
Tenure | Fifield Project (EL8935), 100%-owned by Rimfire, subject to an earn-in under which Golden Plains Resources (GPR) can earn 50.1% by spending $3.6m and arranging mine-development finance |
Leadership | MD & CEO David Hutton; Chairman Ian McCubbing; metallurgy led by consultant Boyd Willis (40+ yrs, ~10 in scandium) |
Stage | Early — first metallurgical test work; results indicative and to be confirmed by longer-duration testing; no economic study yet |
▸ Rimfire's Pitch
Scandium is a genuinely useful critical mineral - it makes aluminium alloys stronger and more weldable (aerospace, lightweighting) and is a key material in solid-oxide fuel cells — but it has never had a reliable, low-cost supply. Part of the reason is processing: most scandium sits in iron-rich laterite deposits that need High Pressure Acid Leaching (HPAL) to extract it, and HPAL is expensive, technically demanding and capital-hungry.
Rimfire’s pitch with Murga is that it might sidestep that problem. Murga’s scandium sits in material with relatively low iron (~16% Fe), versus much higher iron at the other Fifield deposits. Iron is a major acid consumer and a key reason HPAL is needed. Lower iron raises the possibility that Murga could be leached at atmospheric pressure — using simpler, cheaper heap or vat leaching — and the first bottle-roll tests are the opening evidence for that thesis.
Figure 1: Fifield Scandium Projects showing Rimfire and third-party projects, deposits, and prospects.(Source: RIM ASX Announcements)
Managing Director and CEO David Hutton puts the distinction plainly. “Traditionally, scandium is recovered from the laterite-hosted nickel-cobalt-scandium deposits of the sort we’re dealing with here at Fifield through an upfront extraction process — typically a high-pressure acid leach, which is expensive and quite complicated,” he says.
“Once the scandium has been dissolved into solution, that solution is passed through a solvent extraction process, which produces the scandium oxide. What we’re trying to do, which is a little different, is extract the scandium initially using atmospheric leaching rather than high-pressure acid leaching. The key reason is that atmospheric leaching techniques are less complex and less expensive.”
Table 1 — Rimfire’s Fifield scandium inventory
Deposit | Scandium oxide (Sc₂O₃) |
Melrose | 1.1 Kt |
Currajong | 3.1 Kt |
Murga | 11.9 Kt |
Total inventory | >16 Kt |
▸ What the Tests Actually Showed
The work to date is Stage 1: two ~3.5kg composite core samples from Murga (drillhole FI2679) were subjected to bottle-roll leaching at atmospheric pressure and ambient temperature over 14 days (Figure 2).
The first metallurgical examination of Murga material ever undertaken. Two findings stand out. First, the rate of scandium recovery over the 14 days was relatively constant, which is what lets the company extrapolate to 60–90% recovery over a commercially realistic leach cycle (heap leaching of these laterites typically runs 100–250 days). Second, iron extraction — the major acid consumer — was relatively low, which is exactly what you want to see for an atmospheric-leach economic case.
The caveats are equally important, and Rimfire states them clearly: the results are indicative, not definitive, they rest on extrapolating a 14-day rate, and they require confirmation through longer-duration testing. This is an early guide to how the material might behave at scale, not a finished metallurgical answer. As Hutton describes it, “the outcome of these test results clearly demonstrates that there is potential to recover scandium from our Murga deposit using the atmospheric leaching technique… not only is there potential to recover scandium with atmospheric leaching techniques — which are less complex and less expensive than HPAL — but also there is merit in continuing the test work over longer and more commercial time frames to confirm the recovery amounts and extraction rates.”
Figure 2: Photo of Murga Bottle Roll test in laboratory (Source : Rimfire ASX Announcement)
▸ Why Low Iron Is the Whole Story
It is worth dwelling on the iron point, because it is the crux of the Murga thesis. At Rio Tinto’s nearby Burra deposit, the resource iron grade is around 34% Fe; Murga’s is roughly 16% Fe. High-iron scandium deposits at Fifield — Syerston, Flemington, Burra — are generally looking at HPAL, a process that works but carries heavy capital and operating costs and meaningful technical risk. If Murga’s lower iron genuinely enables atmospheric heap leaching, the capital and complexity of getting scandium out drop substantially. That is the “key point of difference” Rimfire is leaning on, and it is why a metallurgical result — not a drill result — is the news here.
Table 2 — Atmospheric leaching vs HPAL
Feature | Atmospheric leaching (Murga’s potential route) | HPAL (high-iron neighbours) |
Pressure & temperature | Ambient pressure; low to moderate temperature | High pressure; high temperature |
Capital intensity | Lower | Higher |
Complexity | Less complex | More complex, technically demanding |
Best suited to | Low-iron material (iron is a major acid consumer) | High-iron laterites |
Fifield example | Murga (~16% Fe) — now under test | Syerston, Flemington, Burra (~34% Fe at Burra) |
For Hutton, this is fundamentally about commercially de-risking the asset. “We have a large deposit, and its geological characteristics, primarily its low iron content, theoretically enable it to be extracted using atmospheric leaching,” he says. The update, in his words, “demonstrates that there is merit in continuing to examine atmospheric leaching as the preferred processing route, and it justifies the ongoing metallurgical test work.”
▸ The Path Forward
Rimfire has already commenced Stage 2: two new bottle-roll tests running over a much longer 160–180 days with weekly sampling, designed to confirm whether the Stage 1 extraction rate holds over a commercial timeframe. Depending on those results, the company may run a column (vat) leach test — a 50kg sample over 3–6 months that simulates a full-scale heap/vat leach and reveals whether issues like slumping or loss of permeability appear.
Running concurrently, an agitated tank leach test (higher acidity, 95°C) will be undertaken as a fallback atmospheric technique should heap/column leaching not deliver economic recoveries. In short: a staged, low-cost program designed to de-risk the processing question step by step, with regular updates promised along the way.
Hutton is clear that heap leaching is the goal, with options if it doesn’t deliver. “We’re definitely trying to demonstrate that atmospheric leaching is the method that we want to use,” he says. “Heap leaching, or static heap leaching, is the typical method — but there are also other atmospheric leaching methods if the heap leaching doesn’t stack up. We can use what we call agitated tank leach as an alternative, which is still leaching at atmospheric pressures, but also introduces a bit of heat into the tank to aid the extraction.”
Concluding Comments
The story for Rimfire is now going to be a test for investors patience. Unfortunately, this is going to be painful but as a long term investor myself, this is the stage that the investing community should be looking seriously.
This release is about Rimfire trying to go through the process of finding a cheaper and more efficient flow sheet. It is a metallurgical update, and obviously not a discovery message. The encouraging news is that Murga’s low-iron scandium might be extractable by a cheaper, simpler route than its high-iron neighbours can use. This is a genuinely important question for scandium projects, because like all metal mining projects, scandium’s problem has never really been geology, instead it is about the cost and complexity of getting it out of the ground and into a saleable product.
Samso’s observation is that the signal here is potentially looking good as the news indicate a relatively constant recovery over 14 days, low iron extraction, and a credible path to atmospheric leaching that would differentiate Murga in Australia’s scandium heartland.
As David Hutton frames it, the update is about commercially de-risking the project and marking Rimfire’s “transition from pure exploration into pre-development.” The noise to resist is over-reading a 14-day, indicative result — the company itself is admirably clear that this needs confirming over a commercial timeframe, and the 60–90% range is wide for a reason.
The next real markers are concrete: the Stage 2 long-duration bottle rolls, the column-leach test that follows, and ultimately, whether all of this converts into a costed, economic flowsheet. For now, Rimfire has taken the first step toward answering the most important question about its scandium inventory.
The Scandium Market Backdrop
The strategic logic behind consolidating scandium ground becomes clearer against the backdrop of how the metal's market actually works. Scandium sits in an unusual category — a market that is tiny in tonnage but disproportionately high in strategic value. Global scandium oxide production has been running at only around 40 tonnes a year, with annual consumption estimated in the range of roughly 15 to 25 tonnes (Figure 5). In a market measured in tens of tonnes, Samso notes that a single credible project can shift the entire supply narrative.
Figure 3: Scandium Market Scale bar chart: 2022 (<40 t) vs 2024 (~40 t) with source notes. (Source: Samso)
That value comes from function rather than volume. Adding a fraction of a percent of scandium to aluminium produces alloys that are lighter, stronger, more weldable and more heat- and corrosion-resistant — properties prized in aerospace, defence and advanced manufacturing — while scandium-bearing ceramics also play a role in solid oxide fuel cells used in clean-energy systems. Scandium appears on the critical minerals lists of Australia, Canada, the European Union and the United States.
Supply, however, is highly concentrated, with China dominating primary production and refining, and most output historically recovered only as a by-product. Samso points to rising Western interest in securing alternative supply, including reported moves by the U.S. Defence Logistics Agency to buy scandium oxide for strategic stockpiles.
Against that picture, New South Wales has emerged as Australia's most concentrated scandium province — described by Samso as the country's scandium hotspot, or the "Kalgoorlie of scandium" — hosting projects spanning exploration through to construction-ready assets, including those of Sunrise Energy Metals, Scandium International Mining and Rimfire.
About Rimfire Pacific Mining Limited
Rimfire Pacific Mining Ltd (ASX: RIM) is an ASX-listed critical minerals explorer focused on building a globally significant scandium resource inventory in Australia's Fifield Scandium District, located approximately 70km northwest of Parkes in central New South Wales.
The company's scandium portfolio comprises three deposits — Melrose, Currajong, and Murga — together delivering a combined global resource inventory of 10.6Kt Sc (16.2Kt Sc Oxide). The Murga Scandium Deposit, the most recently updated, holds an Inferred Mineral Resource of 56.1Mt at 138ppm Sc for 7,760t Sc.
Murga is notable within the Fifield District for its relatively low average iron content of approximately 16% Fe, which creates the possibility that its scandium could be extracted using Atmospheric Tank Leaching or Vat Leaching — simpler and less capital-intensive techniques than the High Pressure Acid Leaching (HPAL) methods being considered by operators of higher-iron deposits in the same district. A metallurgical study to investigate this pathway is now underway.
The company also holds the Malamute Scandium Prospect approximately 40km north of Murga on its 100%-owned Rabbit Trap Project, offering regional resource growth optionality.
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