No Single Method Fits Every Gold Ore
Gold ores vary enormously — from coarse free gold in alluvial deposits to fine gold locked in refractory sulphides. The recovery method, and usually a combination of methods, is selected from ore testwork.
Gravity Concentration
Gravity recovery exploits the high density of gold. Centrifugal concentrators and shaking tables capture coarse, free gold early in the circuit.
- Best for: coarse, free gold; placer and some hard-rock ores.
- Advantage: simple, low operating cost, pulls gold before it can be lost.
- Limitation: less effective on very fine or locked gold.
Flotation
Flotation uses reagents to make gold-bearing minerals attach to air bubbles, concentrating them into a froth. It is ideal for gold hosted in sulphide minerals.
- Best for: gold-bearing sulphide ores.
- Advantage: concentrates the gold for smelting or a smaller leach circuit.
- Equipment: flotation cells up to 320 m³ per unit.
Cyanidation (CIL/CIP)
Cyanidation dissolves fine gold into solution, which is then adsorbed onto activated carbon. It is the workhorse for fine, non-refractory gold ores.
- Best for: fine gold, high overall recovery.
- Advantage: recovery can reach 99% on suitable ores.
- Equipment: leaching tanks up to 20 m × 20 m.
Combining Routes
Most real plants combine methods:
- Gravity before flotation to pull free gold early.
- Flotation to concentrate, then leach the concentrate.
- Heap leaching for low-grade, large-tonnage deposits.
The right combination comes out of testwork. A flowsheet designed on laboratory data — not guesswork — is what protects your recovery and your budget.