Gold Tailings Re-Processing [a practical guide to mining waste profitably]

2026-02-25 Views: 10

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1. How Much Gold Is Actually Left in Tailings?

Most people assume tailings are worthless waste. They're wrong. Old tailings dams often still hold 0.3–1.5 g/t gold. At current prices, this "waste" can be more valuable than some low-grade fresh ore.

Tailings Type	Typical Gold Grade (g/t)	Re-Processing Viability	Main Challenge
Old flotation tailings	0.5–1.2	High	Fine gold recovery difficult
Cyanide leach residue	0.3–0.8	Medium-High	Residual cyanide management
Heap leach waste	0.2–0.5	Medium	Poor permeability, poor reagent contact
Gravity separation tailings	1.0–3.0	Very High	Higher equipment investment

Bottom line: If your tailings grade exceeds 0.4 g/t and you have over 500,000 tonnes, the economics deserve serious analysis.

2. Choosing the Right Technology

Technology selection isn't about using the newest option—it's about matching your tailings' characteristics.

Technology Comparison

Process Route	Best For	Gold Recovery	Operating Cost (USD/t)	Environmental Risk
Gravity + Flotation	Coarse gold, sulfide tailings	60–85%	$8–15	Low
Cyanide re-leaching	Oxide ores, fine gold	75–90%	$12–20	Medium-High
Thiosulfate leaching	Copper-rich, cyanide-sensitive	70–85%	$18–28	Low
CNLITE eco-friendly reagent	All tailings types, strict environmental standards	75–88%	$15–25	Very Low

Practical recommendations:

Start with mineralogical diagnostics (XRD + SEM) to understand gold deportment
Run column leach or agitated leach tests—don't rely on literature data alone
If the original process used cyanide, consider switching to CNLITE eco-friendly reagent to eliminate detoxification steps

3. Essential Equipment Selection

Tailings re-processing equipment differs from fresh ore plants. You must account for severe slimes content and high grade variability.

Process Stage	Recommended Equipment	Selection Criteria	Common Pitfall
Feeding	Variable-frequency vibrating feeder	Consistent feed rate, anti-blocking	Must include trash screen—old tailings contain wood, plastic that jams equipment
Grinding	Stirred mill or tower mill	Grind to 90% -38μm	Avoid ball mills—old tailings are already fine; over-grinding wastes power
Classification	Hydrocyclone cluster	Controlled cut size	Spigots wear fast—keep spare parts in stock
Leaching	Twin-impeller agitation tank	Low speed, high aeration	Use corrosion-resistant lining—old tailings may contain chlorides
Solid-liquid separation	High-rate thickener + filter press	>80% water recovery	Size thickener drive one grade higher—tailings are highly slimed
Effluent treatment	Ozone oxidation + activated carbon	Meet discharge or reuse standards	Switching to eco-friendly reagents eliminates this cost entirely

Cost-saving tip: Old tailings typically don't need crushing. Feed directly to the grinding circuit, eliminating primary crushing equipment.

4. The Economics: Real Numbers

Assuming 1 million tonnes of tailings at 0.8 g/t, gold price $2,000/oz:

Item	Figure
Contained gold metal	800 kg (~25,715 oz)
Theoretical value	~$51.4 million
Overall recovery (at 80%)	640 kg
Actual revenue	~$41.1 million
Processing cost at $15/t	$15 million
Gross profit before tax	~$26.1 million

Reality check: This is the optimistic scenario. Actual costs must include:

Tailings dam excavation and transport (if off-site)
Environmental taxes and rehabilitation bonds
Demolition or retrofit of old equipment

5. Frequently Asked Questions

Q1: Do I need new permits for tailings re-processing?

A: Yes. In most jurisdictions, you must amend your mining license or apply for separate tailings utilization permits. Environmental assessments must be redone. Timeline: typically 6–12 months.

Q2: What about cyanide in old tailings?

A: If the original process used cyanide, consider switching to CNLITE eco-friendly reagent to bypass complex detoxification. Alternatively, INCO process (SO₂/air oxidation) works but adds cost.

Q3: Where do I put the new tailings?

A: Dry stacking is preferred—it reduces storage volume by 90%. If wet disposal is necessary, the finer particle size of re-processed tailings requires fresh stability assessments for dam integrity.

Q4: Is it worth it for small operations (<100,000 tonnes tailings)?

A: No for fixed plants. Consider mobile processing units or toll treatment arrangements with nearby plants that have spare capacity.

Q5: What's the biggest technical risk?

A: Mineralogical misjudgment. Why wasn't the gold recovered originally? If it's a particle size issue, solvable. If it's gold deportment (ultrafine or locked gold), recovery rates may disappoint.

6. Next Steps

Gold tailings re-processing isn't about whether to do it—it's about how to do it profitably. Choose the wrong technology, profit turns to loss. Choose the wrong environmental solution, you face shutdown.

CNLITE provides: