What Is a Comprehensive Gold Ore Processing Guide from Crushing to Cyanidation?

Robin

Senior Economic Geologist & Ore Analyst

2026-06-20

What Is a Comprehensive Gold Ore Processing Guide from Crushing to Cyanidation?

Gold ore processing is a multi-stage operation that transforms raw, mined rock into refined gold. From the initial crushing of ore to the chemical extraction of gold through cyanidation, each step plays a critical role in maximizing recovery and ensuring economic efficiency. This guide outlines the complete process, explaining key stages, equipment, and best practices.

1. Ore Extraction and Transportation

The process begins with mining gold-bearing ore from open-pit or underground operations. After drilling and blasting, the ore is loaded onto haul trucks and transported to the processing plant.

Key objectives at this stage:

• Minimize dilution with waste rock
• Maintain consistent ore grade
• Ensure safe and efficient material handling

2. Crushing Stage

Crushing reduces large rocks into smaller, manageable sizes suitable for grinding.

Primary Crushing

• Equipment: Jaw crushers or gyratory crushers
• Output size: Typically 100–200 mm
• Purpose: Break down large ore chunks into smaller pieces

Secondary and Tertiary Crushing

• Equipment: Cone crushers or impact crushers
• Output size: 10–25 mm
• Purpose: Further size reduction to prepare for grinding

Crushing circuits may be open or closed, depending on desired particle size control.

3. Grinding and Classification

Grinding reduces crushed ore into fine particles to liberate gold from surrounding minerals.

Grinding Equipment:

• Ball mills
• SAG (Semi-Autogenous Grinding) mills
• Rod mills

Ore is mixed with water to form a slurry and ground to a fine particle size, typically 75–150 microns.

Classification:
Hydrocyclones or vibrating screens separate fine particles from coarse material. Oversized particles are returned to the mill for further grinding.

Purpose:

• Achieve optimal gold liberation
• Prepare slurry for downstream concentration or leaching

4. Gravity Concentration (Optional)

If the gold is coarse and free-milling, gravity separation can recover a portion before chemical treatment.

Common equipment:

• Shaking tables
• Spiral concentrators
• Centrifugal concentrators (e.g., Knelson, Falcon)

Advantages:

• Reduces cyanide consumption
• Improves overall recovery
• Low operating cost

5. Cyanidation (Gold Leaching)

Cyanidation is the primary chemical process for extracting gold from finely ground ore.

Principle:
Gold dissolves in a dilute cyanide solution in the presence of oxygen, forming a soluble gold-cyanide complex.

Leaching Methods:

1. CIL (Carbon-in-Leach)

   • Cyanide leaching and gold adsorption occur simultaneously
   • Activated carbon adsorbs dissolved gold

2. CIP (Carbon-in-Pulp)

   • Leaching occurs first
   • Gold is then adsorbed onto carbon

3. Heap Leaching

   • Used for low-grade ores
   • Cyanide solution percolates through stacked ore heaps

Key control parameters:

• pH level (typically 10.5–11)
• Cyanide concentration
• Dissolved oxygen
• Retention time

6. Gold Recovery from Carbon

Once gold is adsorbed onto activated carbon, it must be recovered.

Elution (Desorption):
Gold is stripped from carbon using hot caustic cyanide solution.

Electrowinning:
Gold is recovered from solution by passing an electric current through it, causing gold to plate onto cathodes.

Smelting:
The recovered material is dried and smelted to produce doré bars (a semi-pure gold product).

7. Tailings Management

After gold extraction, the remaining slurry (tailings) must be safely managed.

Key components:

• Detoxification of residual cyanide
• Tailings storage facilities (TSFs)
• Water recycling systems

Modern plants focus on environmental compliance and minimizing ecological impact.

8. Process Optimization and Control

To ensure maximum gold recovery and cost efficiency, operators monitor:

• Particle size distribution
• Leach kinetics
• Carbon activity
• Reagent consumption
• Recovery rates

Automation and real-time monitoring systems improve consistency and reduce operational risk.

Conclusion

A comprehensive gold ore processing flow—from crushing to cyanidation—integrates mechanical size reduction, mineral liberation, chemical leaching, and final recovery. Each stage must be carefully designed and optimized to maximize gold recovery, reduce costs, and meet environmental standards. When properly managed, this systematic approach ensures efficient transformation of raw ore into valuable gold bullion.

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