Gold Carbon-in-Leach (CIL) Processing Plant

I. Overview of CIL Technology

The Carbon-in-Leach (CIL) gold processing plant represents a significant advancement in cyanidation technology by integrating leaching and adsorption processes within the same reactor system. This method is particularly effective for treating sulfide ores, oxide ores, and complex mineral associations, achieving gold recovery rates of 96%-99%. Compared to traditional Carbon-in-Pulp (CIP) plants, CIL plants offer:

· 20%-30% energy savings through process consolidation

· Enhanced stability against ore grade fluctuations (0.5-15g/t)

· Reduced capital costs with compact plant layout

Modern CIL plants feature four automated modules: crushing/grinding, leaching/adsorption, elution/electrowinning, and carbon regeneration.

II. Core Process Flow

1. Ore Preparation

(1) Crushing & Grinding

Three-stage crushing reduces ore size to ≤10mm. Ball mills with hydrocyclones produce slurry with 95% passing 200 mesh.

(2) Slurry Conditioning

Thickeners concentrate slurry to 45%-50% solids, with initial NaCN dosage (0.02%-0.05%).

2. CIL Leaching-Adsorption

(1) Reactor Design

8-10串联的CIL tanks (300-500m³ each) equipped with:

· Dual-impeller agitators (40-60rpm)

· 316L stainless steel screens (0.8-1.2mm)

· Real-time monitoring of Eh (-200mV to -400mV) and DO (6-10ppm)

Coconut-shell activated carbon (1.0-3.35mm) moves counter-currently to slurry flow.

(2) Key Parameters

· Cyanide gradient: 0.05%-0.08% (first tank) → 0.01%-0.03% (last tank)

· Carbon density: 10-30g/L

· Total retention time: 24-36h

3. Loaded Carbon Treatment

(1) Acid Washing

5%-10% HCl removes surface contaminants.

(2) Zadra Elution

· Pressure: 0.5-0.6MPa

· Temperature: 130-150℃

· Eluant: 1% NaOH + 0.2% NaCN

· Gold desorption rate: >99%

(3) Electrowinning

Gold-rich solution (200-500ppm Au) is electrolyzed at 10-15A/m², achieving ≥99.5% deposition efficiency.

4. Carbon Regeneration

· Acid wash: 3% HNO₃

· Thermal reactivation: 750-800℃ in rotary kiln

· Regeneration recovery: 90%-95%

III. Competitive Advantages

1. Economic Benefits

2. Environmental Performance

· Cyanide destruction: H₂O₂/CuSO₄ system reduces CN⁻ to<0.5ppm

· Water recycling rate: ≥95%

· Dry tailings stacking:<15% moisture

IV. Case Study: 2000t/d CIL Plant

Key Data:

· Ore type: Quartz vein gold ore, 3.2g/t Au

· Equipment:

o  Ball mill: Φ4.2×6.5m, 2800kW

o  CIL tanks: 10×450m³

· Performance:

o  Recovery rate: 98.7%

o  Carbon loading: 4500g/t

o  Operating cost: $22.3/t

V. Future Innovations

1.        Digital Transformation

o  AI-driven leaching optimization

o  Digital twin simulation

2.        Green Technologies

o  Thiosulfate leaching replacing cyanide

o  Microwave-assisted elution

3.        Material Science

o  Graphene-enhanced activated carbon

o  Corrosion-resistant ceramic coatings