JOHN FINLAY MINING中文JOHN FINLAY MINING中文Low-grade feed at 0.20% Cu still justified pre-concentration — recovery held at 94.7% while 38% of mass left the circuit, and a 1 Mt/a plant was designed on the result.
| Product | Yield % | Grade % | Recovery % |
|---|---|---|---|
| Concentrate | 61.78 | 0.31 | 94.72 |
| Rejects | 38.22 | 0.03 | 5.28 |
| Feed | 100.00 | 0.20 | 100.00 |
The economics scale directly: every rejected tonne saves grinding energy (~40% of a concentrator's power bill). The campaign concluded with a preliminary design for a 1,000,000 t/a pre-rejection plant.
At 0.20% Cu, the Lujiang ore sits below many operations' cut-off grade — the textbook candidate for the pre-concentration argument. If rejection cannot make this ore pay, it stays in the ground; if it can, a resource gets converted into reserves.
The cut rejected 38.22% of mass at 0.03% Cu — a rejects grade one-seventh of feed — losing only 5.28% of the copper and holding recovery at 94.72%. The enrichment ratio (1.55×) is modest by design: at this feed grade the optimization target is maximum safe rejection, not maximum concentrate grade. Every rejected tonne is a tonne of grinding (15–25 kWh) and flotation capacity returned to the mill.
| Item | Value |
|---|---|
| Feed size fraction | 0.5–8mm |
| Separator | Pressurized two-product dense medium cyclone |
| Medium | Ferrosilicon + magnetite powder, closed-circuit recovery |
| Density control | In-line density gauge with automatic water/medium make-up loop |
| Value mineral density | Chalcopyrite: 4.1–4.3 g/cm³ |
| Gangue density | Silicate gangue: 2.6–2.7 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 passed once through a pressurized two-product cyclone. 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.
The result carried directly into a preliminary design for a 1,000,000 t/a pre-rejection plant: roughly 380,000 t/a of barren rock intercepted before the mill, concentrator throughput effectively raised by the same amount, and unit operating cost per tonne of copper cut accordingly. This is the template study for making marginal Chinese copper deposits economic.
Market context: Beneficiation for Indian copper & lead-zinc
Q: What recovery did dense medium separation achieve on this copper ore?
A: 94.72% Cu recovery with 38.22% of mass rejected at just 0.03% Cu, from a 0.20% feed (0.5–8 mm).
Q: Will this work on my copper 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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