Activated carbon is the backbone of gold extraction in CIL and CIP circuits. The right carbon means higher gold loading, fewer losses, and lower cost per ounce recovered. The wrong one means money left in the tailings.
This guide covers what you actually need to know when sourcing activated carbon for gold recovery — specs, grades, pricing, and how to avoid overpaying.
Activated carbon adsorbs gold-cyanide complexes [Au(CN)₂]⁻ from leach slurry. It's used in three main circuit types:
| Process | How It Works | Carbon Contact |
| CIL (Carbon-in-Leach) | Carbon added directly to leach tanks | 8–24 hours |
| CIP (Carbon-in-Pulp) | Carbon contacts already-leached pulp | 4-8 hours |
| CIC (Carbon-in-Column) | Heap leach solution passes through carbon columns | Continuous |
In all three, gold loads onto the carbon surface, then gets stripped (desorbed) with hot caustic cyanide solution, and the carbon gets reactivated for reuse.
A well-performing carbon typically achieves 95–99% gold recovery from solution.
Not all activated carbon works for gold. Here's what separates gold-grade carbon from generic water treatment carbon:
| Parameter | Gold Recovery Grade | Water Treatment Grade |
| Iodine Number | 1000–1100 mg/g | 800–1000 mg/g |
| Gold Activity (K value) | ≥25 mg Au/g | Not tested | |
| Hardness Number | ≥98% | ≥98% |
| Particle Size | 6×12 mesh (1.7–3.35mm) | Various |
| Ash Content | ≤3% | ≤3% |
| Moisture | ≤5% | ≤5% |
| Apparent Density | 0.45–0.55 g/mL | 0.45–0.55 g/mL |
The two specs that matter most: hardness and gold activity.
Hardness determines how many reactivation cycles your carbon survives. Low hardness = high attrition = carbon loss = gold loss. In a typical CIL plant, carbon goes through 50–200 reactivation cycles over its lifetime.
Gold activity (K value) measures how fast and how much gold the carbon can adsorb. Tested by the Mintek method or similar — if your supplier can't provide this number, that's a red flag.
Short answer: coconut shell wins for gold recovery, almost always.
| Factor | Coconut Shell | Coal-Based |
| Hardness | 98–99% | 92–95% |
| Gold Activity | Higher (micropore-dominant) | Lower |
| Attrition Loss | 0.5–2% per cycle | 3–5% per cycle |
| Reactivation Cycles | 100–200+ | 50–100 |
| Price (FOB China) | $1,800–3500/ton | $500–2000/ton |
| Best For | CIL/CIP circuits | CIC columns, lower-grade ores |
Coconut shell carbon has a micropore-dominant structure (pore diameter <2nm), which is ideal for adsorbing the relatively small gold-cyanide complex. Coal-based carbon has more mesopores — better for larger organic molecules, not as efficient for gold.
When coal-based makes sense: If you're running a heap leach with CIC columns and your solution is relatively clean (low organics), coal-based can work at a lower cost. But for CIL/CIP with abrasive slurry, coconut shell's hardness advantage pays for itself.
Choosing carbon isn't just about specs on a datasheet. Consider these factors:
Your circuit type,
Your ore characteristics,
Your reactivation setup,
Total cost of ownership. Don't just compare $/ton. Calculate:
True cost = (Carbon price × Annual consumption) + (Gold lost to attrition) + (Reactivation cost × Cycles/year)
A $2,200/ton coconut shell carbon that lasts 150 cycles often costs less than a $1,400/ton coal-based carbon that lasts 60 cycles — especially when you factor in the gold trapped in discarded fines.
At our factory, we produce coconut shell activated carbon specifically for gold mining operations. Here are our standard gold-grade specs:
| Parameter | Our Standard | Our Premium |
| Raw Material | 100% coconut shell | 100% coconut shell |
| Iodine Number | ≥1000 mg/g | ≥1100 mg/g |
| Gold Activity (K) | ≥28 mg/g | ≥32 mg/g |
| Hardness | ≥98% | ≥98% |
| Particle Size | 6×12 mesh | 6×12 mesh |
| Ash Content | ≤2.5% | ≤2% |
| Moisture | ≤5% | ≤5% |
| MOQ | 1 ton | 1 ton |
| Packaging | 25kg PP bags or 500kg jumbo bags |
We test every batch for gold activity — not just iodine number. We can provide SGS or third-party test reports on request.
Current production capacity: 500 tons/month for gold-grade carbon.
Problem: Gold recovery dropping over time
Problem: High carbon attrition
Problem: Gold not stripping completely
Problem: Inconsistent quality between shipments
For CIL/CIP gold recovery, target an iodine number of 1000–1100 mg/g. But don't rely on iodine number alone — it measures total adsorption capacity for small molecules, not specifically gold. Always ask for the gold activity (K value) test result, which directly measures gold adsorption performance. A carbon with iodine 1050 and K value ≥28 is a solid performer.
In a well-managed CIL/CIP circuit, coconut shell activated carbon typically lasts 100–200 reactivation cycles before it needs full replacement. That translates to 1–3 years depending on your reactivation frequency and ore abrasiveness. Annual carbon consumption for a typical 3,000 tpd gold plant runs 50–150 tons.
The carbon specs are essentially the same — both need high hardness, high gold activity coconut shell carbon in 6×12 mesh. The difference is operational: CIL carbon sees more abrasion because it's in the leach tanks with fresh ore, so you may want to spec slightly higher hardness (≥98.5%) for CIL versus ≥98% for CIP.
Technically yes, but it's wasteful. Gold-grade carbon costs more because it's made to tighter specs (higher hardness, tested for gold activity, lower ash). Water treatment carbon doesn't need these properties. Going the other direction — using water treatment carbon for gold — will give you poor recovery and high attrition losses. Don't do it.
Three quick checks on delivery:
Visual: Uniform black granules, no dust or fines, no foreign material.
Hardness test: Shake a sample in a sealed container for 5 minutes, screen at 12 mesh — loss should be <5%,
Moisture: Weigh, oven-dry at 105°C for 2 hours, reweigh — should be <5%,
For gold activity, you'll need a lab test (takes 24–48 hours). We provide pre-shipment test reports so you know what's coming.
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Looking for gold-grade activated carbon? We supply mines in Ghana, Tanzania, Sudan, Indonesia, and across Africa and Southeast Asia.
Tell us your circuit type, tonnage, and current carbon specs — we'll recommend the right grade and send a competitive quote.
