Activated Carbon for CIC Gold Recovery: Selection for Heap Leach Operations

How to balance adsorption performance, solution flow, bed pressure drop, particle size, and carbon retention in carbon-in-column circuits

Date: October 18, 2026        Author: YICARB Technical Expert (15+ years experience in activated carbon industry)

Introduction

Activated carbon for CIC gold recovery is selected for a different operating environment from carbon used in CIP or CIL. In heap-leach operations, pregnant leach solution (PLS) is collected from the leach pad, clarified as required, and passed through carbon-in-column (CIC) equipment so dissolved gold can adsorb onto granular activated carbon. Because the feed is a solution rather than ore slurry, column hydraulics, contact time, particle-size distribution, and carbon retention become central selection factors.

Figure 1: Typical heap-leach solution flow through clarification and CIC carbon columns.

1. How CIC Differs from CIP and CIL

In CIP, carbon is contacted with leached pulp in a separate adsorption train; in CIL, leaching and adsorption occur together in slurry tanks. CIC instead treats gold-bearing solution in columns, commonly after heap or vat leaching. The absence of most ore solids generally reduces abrasive contact, but it does not remove the need for durable carbon. Pumping, carbon transfer, backwashing, elution, regeneration, and fluid movement can still create attrition and fines.

CIC systems may use fixed beds or fluidized/expanded beds, depending on the design. The operating checks are not identical: fixed beds require close attention to pressure drop and flow distribution, while fluidized systems also need appropriate upflow velocity and bed expansion to avoid carbon carryover.

2. Flow Rate and Contact Time

Flow rate determines how much PLS passes through the carbon inventory and influences the time available for adsorption. In a fixed-bed column, empty bed contact time (EBCT) is often used as a preliminary design measure: carbon-bed volume divided by volumetric flow rate. It is not a guarantee of actual adsorption performance, because flow distribution, channeling, gold concentration, solution chemistry, and the condition of the carbon also matter.

If flow rises without a corresponding change in column capacity, contact time may fall and gold breakthrough can occur earlier. Reducing flow may improve contact but can limit plant throughput. The practical target is therefore the designed operating range, verified by solution assays and carbon-loading data—not simply the lowest possible flow rate.

3. Bed Pressure Drop and Solution Distribution

In fixed-bed CIC columns, rising pressure drop can signal restricted flow paths. Causes include suspended solids or colloids in the PLS, scale, excessive fines, uneven particle-size distribution, compaction, or poor inlet distribution. Trend pressure drop at a consistent flow rate so readings can be compared reliably.

Match clarification and filtration to the feed, and inspect inlet distributors, support screens, drains, and backwash performance. Backwashing can remove deposits, but excessive backwashing may disturb the bed or carry carbon out of the column.

4. Particle Size, Fines, and Mechanical Durability

CIC carbon size must balance adsorption kinetics, hydraulics, and retention. Smaller particles may adsorb faster but can increase packed-bed resistance and escape through mismatched screens. Larger particles often provide easier retention and lower pressure drop, although adsorption may be slower under comparable conditions.

For activated carbon for CIC gold recovery, both 6×12 and 8×16 mesh may be suitable, depending on column design, flow regime, screen aperture, and target loading. Review a sieve analysis showing on-size, oversize, and undersize fractions; a mesh label alone does not describe the full particle-size distribution.

Hardness and attrition resistance still matter during transfer, elution, regeneration, backwashing, and fluidized-bed movement. Excess fines can restrict flow, pass through screens, and carry adsorbed gold out of the circuit.

Figure 2: Flow distribution, bed resistance, and screen retention are linked in CIC column operation.

5. Practical CIC Carbon Selection Checklist

6. Application Example

Illustrative example—not a customer case study: A heap-leach plant records rising column pressure drop and higher outlet gold. The team first compares readings at the same flow, then checks PLS clarification, screens, fines, and flow distribution before changing the carbon grade.

YICARB Perspective

YICARB recommends evaluating gold loading and kinetics alongside particle-size distribution, fines control, durability, screen compatibility, and column hydraulics. Representative-PLS testing provides a stronger basis for selection than mesh size alone.

Conclusion

The right activated carbon for CIC gold recovery balances gold adsorption with stable flow, manageable pressure drop, and reliable retention. Confirm flow and contact-time requirements, screen compatibility, clarification, particle-size distribution, and durability before selecting a grade for consistent CIC performance.