JOHN FINLAY MINING中文JOHN FINLAY MINING中文Our first hard-rock lithium campaign proved dense medium cyclones produce a saleable-grade spodumene concentrate before any flotation.
| Product | Yield % | Li₂O % | Recovery % |
|---|---|---|---|
| Concentrate | 15.34 | 4.08 | 69.12 |
| Middlings | 21.45 | 0.96 | 22.78 |
| Rejects | 63.21 | 0.12 | 8.10 |
| Feed | 100.00 | 0.91 | 100.00 |
Spodumene (3.15 g/cm³) against quartz-feldspar gangue (~2.6) is a textbook dense-medium application — the same physics behind the world's major hard-rock lithium operations. A middlings stream is retained for regrinding or flotation feed.
The feed was a Tajik pegmatite spodumene ore at 0.91% Li₂O — squarely in the range where hard-rock lithium projects live or die on processing cost. Dense medium separation (DMS) is the global industry's standard first stage for spodumene precisely because the density contrast against quartz-feldspar gangue (3.15 vs ≈2.6 g/cm³) is clean and liberation is coarse.
The three-product circuit tells a richer story than a single cut: a 4.08% Li₂O concentrate (≈51% spodumene by mineral content, enrichment ratio 4.5) at 15.34% yield; a 0.96% middlings stream holding a further 22.78% of the lithium, ideal for regrind-flotation; and 63.21% of the mass rejected at 0.12% Li₂O carrying just 8.10% of the metal. Combined DMS-recoverable lithium: 91.9% across concentrate plus middlings. Chemical-grade converters typically ask 5.5–6.0% Li₂O — reachable here with a light flotation polish of the DMS concentrate.
| Item | Value |
|---|---|
| Feed size fraction | 0.5–8mm |
| Separator | DMC, three-product circuit (concentrate–middlings–rejects) |
| Medium | Ferrosilicon + magnetite powder, closed-circuit recovery |
| Density control | In-line density gauge with automatic water/medium make-up loop |
| Value mineral density | Spodumene: 3.15 g/cm³ |
| Gangue density | Quartz, feldspar: 2.56–2.65 g/cm³ |
| Process water | 0.1 m³/t, fully recirculated |
| Medium drainage | Sieve bends + drain-and-rinse screens |
The ore was first wet-screened to remove the −0.5 mm slimes (evaluated separately for flotation). The 0.5–8mm fraction was fed to a ferrosilicon/magnetite suspension; a density-gradient series located the optimum cut density, after which the sample was separated in a concentrate–middlings–rejects three-product sequence. Products were drained on sieve bends, rinsed on drain-and-rinse screens, dewatered, sampled and assayed to compute yield, grade and recovery. Dilute medium was recovered by magnetic separation and densified back to the correct-medium sump under closed-loop density control.
This was our first hard-rock lithium campaign, and it validated the standard architecture on Central Asian ore: DMS front end carrying the tonnage, flotation only where chemistry demands it. For a developer, the practical consequence is a materially smaller flotation plant, lower reagent logistics into a remote site, and a saleable pre-concentrate available early in the ramp-up.
Market context: Southern Africa lithium DMS · Mongolia & Central Asia
Q: What recovery did dense medium separation achieve on this spodumene ore?
A: 69.12% of Li₂O into a 4.08% concentrate plus 22.78% into middlings — 91.9% DMS-recoverable in total (0.5–8 mm).
Q: Will this work on my spodumene deposit?
A: Density separation depends on liberation size and density contrast, not on locality. A one-tonne representative sample answers the question definitively — washability results within 24 hours of sample receipt.
Send ~1 tonne of representative ore — washability results within 24 hours of sample receipt.
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