Flotation + Concentrate Leach Route

Process Fundamentals

The flotation + concentrate leach route is designed specifically for refractory and preg-robbing ores. Instead of leaching the entire mass, flotation selectively recovers sulfide-hosted gold into a small, high-grade concentrate.

Typical mass pulls range from 5–15%, meaning only a fraction of the total tonnage enters the high-cost circuit (UFG + CIL). This dramatically improves the economics of treating refractory tailings.

The flowsheet generally includes:

• Conditioning and reagent addition
• Rougher flotation
• Scavenger flotation
• Concentrate thickening
• Ultra-fine grinding (10–20 µm)
• Intensive leaching (CIL or ILR)

This route is widely used in modern refractory gold operations.

Preg-Robbing Handling

Flotation naturally separates carbonaceous material from sulfide minerals. Preg-robbing carbon tends to float poorly, meaning it reports to the tailings stream rather than the concentrate.

This is a major advantage over Direct CIP, where preg-robbing carbon remains fully mixed with the leach slurry.

Once the concentrate is isolated, ultra-fine grinding exposes encapsulated gold, and intensive leaching ensures rapid dissolution before preg-robbing can occur.

This is why flotation-based flowsheets routinely achieve 80–85%+ recovery on material where CIP struggles to reach 50%.

Environmental Strategy

A key advantage of the flotation route is the reduced cyanide footprint. Only the concentrate — not the entire mass — is exposed to cyanide.

This results in:

• Lower cyanide consumption
• Smaller detoxification circuits
• Reduced environmental bonding requirements
• Lower long-term liability for cyanide-bearing tailings

The bulk of the tailings stream remains cyanide-free, allowing for simpler storage and rehabilitation.

For investors, this translates into lower sustaining capital and a more favorable ESG profile.