Tungsten Mining Hits 65.9% Grade as Watershed Flowsheet Confirmed for DFS
Key Takeaways
- Metallurgical testwork at Watershed has confirmed the DFS process flowsheet, producing tungsten concentrate grading up to 65.9% WO₃ — meeting or exceeding typical customer saleable product specifications.
- X-ray ore-sorting at TOMRA achieved 88% mass rejection at 82% WO₃ recovery, directly reducing the size and cost of the downstream processing plant and lowering both capital and operating expenditure.
- Two commercial-grade marketing samples have been dispatched to potential offtake partners across Asia, Europe and North America, with both samples recording sulphur impurity levels of just 0.02%.
- The Watershed DFS remains on track for completion in October 2026, with a Final Investment Decision targeted for Q4 2026.
- A 134-tonne bulk sample is currently being processed at pilot scale to generate larger concentrate volumes for customer evaluation, supporting offtake negotiations running in parallel with the DFS.
Watershed metallurgical testwork delivers outstanding results, confirming DFS process flowsheet
Tungsten Mining (ASX: TGN) has completed a metallurgical testwork campaign at its Watershed Tungsten Project in Far North Queensland, achieving two milestones simultaneously: the process flowsheet for the Definitive Feasibility Study (DFS) has been confirmed, and multiple commercial-grade concentrate samples have been dispatched to potential offtake partners. The company is engaging with potential partners across Asia, Europe and North America.
The testwork produced tungsten concentrate grading up to 65.9% WO₃, confirming the project’s ability to meet or exceed typical customer saleable product specifications. The DFS remains on track for completion in October 2026, with a Final Investment Decision (FID) for the Watershed Project targeted for Q4 2026. For investors, this is a project de-risking milestone: the metallurgy works, the process is confirmed, and concentrate samples have been dispatched to potential customers.
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Inside the testwork — how Watershed ore becomes a premium product
The Watershed process flowsheet uses three sequential stages to upgrade ore from a sorting feed grade of 0.25% WO₃ to a saleable concentrate above 65% WO₃. Testwork was conducted at TOMRA (Castle Hill, NSW) for ore-sorting and at NAGROM in Perth for all downstream beneficiation.
Stage 1 — X-ray ore-sorting rejects 88% of waste before wet processing
Ore-sorting testwork was conducted at TOMRA using X-ray Transmission (XRT) sorting technology. The process identifies tungsten-bearing minerals by density and physically separates them from barren waste material before any wet processing begins.
Results were strong. The P1 Accepts fraction achieved a grade of 4.2% WO₃ from a feed grade of 0.25%, representing a greater than 16x upgrade. Across the sorting passes, the testwork demonstrated 88% mass rejection at 82% WO₃ recovery.
For investors, the significance is straightforward: rejecting 88% of waste material at this early, coarse stage directly reduces the size and cost of the downstream processing plant, lowering both capital and operating expenditure.
| Product Stream | Mass (%) | WO₃ (%) | WO₃ Recovery (%) |
|---|---|---|---|
| P1 Accepts | 3.6 | 4.2 | 59.8 |
| P1 + P2 Accepts | 5.6 | 3.2 | 69.9 |
| P1 → P3 Accepts | 12.1 | 1.7 | 81.8 |
| P1 → P4 Accepts | 27.0 | 0.89 | 94.5 |
| Sorting Feed | 100 | 0.25 | 100 |
Stage 2 — Gravity separation achieves concentrate grades exceeding 30% WO₃
The ore-sorter accepts and the fines fraction (material below 10 mm) were ground to P100 250 µm and processed through wet table gravity separation. This stage exploits the higher density of scheelite relative to waste minerals, producing concentrate grades exceeding 30% WO₃ at high recoveries across all samples tested.
Notably, scheelite at Watershed exhibits relatively coarse liberation characteristics, meaning near-concentrate grades are achievable at a comparatively coarse grind size. In practical terms, this translates to lower energy consumption and a smaller grinding circuit.
Stage 3 — Cleaning stages upgrade product to 53% and beyond 65% WO₃
Gravity concentrate was reground to P100 150 µm before entering the cleaning circuit. Sulphide flotation — which selectively removes gangue sulphide minerals — combined with secondary wet tabling produced a concentrate grade of 53% WO₃. Additional scheelite flotation cleaning stages further upgraded the product to above 65% WO₃.
The initial processing facility will be designed to produce a +50% WO₃ product, with the circuit designed to be modular so that a +65% WO₃ production capability can be added on in future.
Why tungsten concentrate grade matters to investors
WO₃ stands for tungsten trioxide, the commercially traded form of tungsten. Concentrate grade directly determines whether a product is saleable and the price it achieves. The testwork confirms that Watershed can produce concentrates at both the +50% and +65% WO₃ thresholds, which meet or exceed typical customer saleable product specifications according to the announcement.
Tungsten itself is a critical mineral with no close substitute in many applications. It holds the highest melting point of all elements except carbon (around 3,400°C), making it indispensable for cemented carbides, high-speed steels, aerospace and defence components, electronics, and automotive manufacturing. Demand is structurally supported by the fact that China dominates global primary tungsten supply, leaving producers outside China scarce and strategically valuable.
For Watershed, that supply dynamic creates a favourable backdrop. A project capable of producing high-grade, low-impurity concentrate has a clear commercial pathway, particularly with offtake partners across multiple regions already engaged.
Commercial-grade samples dispatched as offtake negotiations advance
Two marketing samples processed through the full flowsheet confirmed the ability to produce concentrates meeting customer specifications, with overall recovery ranging between 60% and 70%. Both samples demonstrated very low sulphur impurity levels:
- Sample 1: Feed 0.32% WO₃ → Product 53.8% WO₃ (sulphur at 0.02%)
- Sample 2: Feed 0.25% WO₃ → Product 65.9% WO₃ (sulphur at 0.02%)
The company is currently engaging with potential offtake partners across Asia, Europe and North America, with commercial terms under discussion. Binding offtake agreements are targeted to align with DFS completion. Importantly, no binding offtake agreements have been entered into as at the date of this announcement, and there is no certainty that binding agreements will be concluded on commercially acceptable terms or at all.
To generate larger concentrate volumes for customer evaluation, a bulk sampling programme excavated approximately 134 tonnes of mineralised material from a high-grade zone outcropping at surface at the northern end of the deposit. The crushed material is currently being processed at pilot scale, with the -40mm+10mm fraction X-ray ore-sorted at TOMRA’s Sydney facility and the -10mm fraction undergoing gravity and flotation testwork at Nagrom in Perth.
A rock chip sample taken from the bulk sample zone returned an assay of 64.3% WO₃ over a 16.9 kg sample. It should be noted this is a selective grab sample from an area of high-grade mineralisation outcropping at surface; grab samples are selective by nature and are not representative of mineralisation across the Watershed deposit or of any future production grade.
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DFS completion and FID — what happens next
With the process flowsheet confirmed and concentrate samples dispatched to potential customers, the company has outlined a clear sequence of near-term milestones:
- Technical collaboration with potential long-term offtake partners on concentrate optimisation for downstream process requirements
- Discussions on indicative commercial offtake terms progressing in parallel with technical work
- Pilot-scale testwork on the 134 tonne bulk sample continuing at TOMRA (Sydney) and Nagrom (Perth) to generate substantially larger concentrate volumes for customer evaluation
- DFS targeted for completion in October 2026
- FID for the Watershed Project targeted for Q4 2026
The company is deliberately investigating the allocation of future production across several markets, aiming to avoid reliance on any single customer or region. Taken together, a confirmed process flowsheet, commercial-grade samples in the hands of potential customers, and an anchored DFS and FID timeline represent a materially de-risked proposition for investors tracking Watershed’s progression toward a development decision.
Mt. Mulgine tungsten project economics illustrate the scale of returns that feasibility-stage tungsten developments outside China can generate, with studies pointing to $1.0-1.4 billion in projected returns for a project at a comparable stage of development.
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