Heap leaching is the most cost-effective method for processing low-grade, oxidized copper-gold ores. It allows mines to recover both copper and gold through a two-step leaching system: acid leaching for copper, followed by cyanide leaching for gold.
This process is widely used for large-scale, low-grade deposits (0.3–1.5 g/t Au) with low investment and stable operating costs. Below is the complete workflow for copper-gold ore crushing and heap leaching.
1. Ore Preparation: Crushing & Screening
Crushing is the first step to ensure high leaching efficiency and good permeability.
- Primary crushing: Run-of-mine ore is crushed to ≤200 mm by jaw or gyratory crusher.
- Secondary & tertiary crushing: Cone crushers reduce ore to 30–50 mm, with closed-circuit screening.
- Fine crushing (optional): HPGR (high-pressure grinding roll) is used to reach 10–25 mm for better leaching.
- Screening: Ore <5 mm can be granulated or stacked directly; oversize returns for re-crushing.
2. Granulation (For Clayey or Fine Ore)
Granulation is strongly recommended for ores with high clay or fine powder content.
- Add binders: cement (2–5 kg/t), lime or other adhesives.
- Use a rotary granulator to form uniform pellets.
- Purpose: improve heap permeability, avoid clogging the leaching pad.
3. Heap Stacking
A well-designed heap ensures safe operation and high recovery.
- Heap structure: HDPE anti-seepage membrane + sand cushion + collection pipes.
- Stacking method: truck or conveyor stacking, single layer 5–10 m, total height 20–60 m.
- Sprinkler system: drip or spray irrigation for uniform leaching.
4. Heap Leaching (Core Process)
Copper-gold ore uses a two-stage leaching design to reduce cyanide consumption and improve metal recovery.
- Leaching agent: sodium cyanide solution (0.02%–0.1%), pH adjusted to 10.5–11 with lime.
- Spraying rate: 8–20 L/(h·m²), intermittent spraying (e.g., 1 hour on, 2 hours off).
- Leaching cycle: 30–90 days (depends on ore type, particle size and temperature).
- Copper interference control: when Cu >0.1%, use ammonia-cyanide system or acid pre-leaching to remove copper first.
5. Pregnant Solution Collection & Gold Recovery
- Collection system: Leachate flows by gravity to the pregnant solution pond.
- Gold recovery:
- Activated carbon adsorption (CIP/CIC): gold is adsorbed onto carbon, then sent for desorption.
- Merrill-Crowe (zinc dust precipitation): less used for large-scale heap leaching.
6. Barren Solution Recycling & Treatment
- Barren solution is reused after adding cyanide and lime.
- Partial open-circuit treatment to avoid accumulation of copper, thiocyanate and other impurities.
7. Copper Recovery (SX-EW)
When copper concentration is high, solvent extraction and electrowinning (SX-EW) is the most efficient way to recover high-purity copper cathode before gold extraction.
This is the core strength of PRS for copper-gold projects.
Key Control Parameters
- Crushing size P80: 10–30 mm
- Single-layer heap height: 5–20 m
- NaCN concentration: 0.02%–0.1%
- pH value: 10.5–11
- Leaching time: 30–90 days
- Gold leaching rate: 60%–85% (low-grade ore)
Important Notes
- Environmental protection: HDPE anti-seepage, cyanide leakage prevention, tailings detoxification.
- Copper interference: copper consumes cyanide sharply; economic evaluation is required when Cu >0.2%.
- Ore type: sulfide copper ore (e.g., chalcopyrite) has poor heap leaching effect and needs pre-oxidation.
Why Choose PRS for Copper-Gold Heap Leaching Projects?
Sichuan Precision Technology (PRS) is a professional EPC service provider for copper & zinc hydrometallurgy.
We provide turnkey solutions for copper-gold ore crushing, granulation, heap leaching, SX-EW and gold recovery systems.
Our services include:
- Professional plant design & 3D layout
- Complete equipment supply (crushers, granulators, heap leaching systems, SX-EW plants)
- CIF shipping, onsite installation & commissioning
- 7×24h online support & full lifespan service
- Low investment, short payback period (≈1 year)
Whether you are planning a new copper-gold heap leaching project or upgrading an existing system, PRS delivers reliable, cost-effective solutions tailored to your ore and capacity goals.
