By the YELI Technical Team · Updated August 2026 · 10 min read
Short answer: For gold recovery in CIP/CIL plants, the industry standard is coconut shell granular activated carbon (GAC) with iodine 1000-1300 mg/g, hardness 98%+ with 98%+ stably available for Mali-grade CIL duty, 6x12 / 8x16 mesh or 3x6 mm, low ash, COA with every batch. Coconut shell carbon wins because its fine micropores (1-2 nm) match the gold cyanide complex, its hardness minimizes fines that carry gold out of the circuit, and it regenerates cleanly. Price for gold-grade runs $3,200-3,800/t FOB China in 2026.
If you are buying activated carbon for a gold plant — whether you run CIP, CIL or are commissioning a new circuit — this guide covers everything we get asked, in the order buyers actually ask it. Use it to spec your carbon, compare suppliers and avoid the expensive mistakes.
1. Why Coconut Shell Carbon Wins for Gold
The gold cyanide complex [Au(CN)2]- is a small molecule, roughly 1-2 nm in diameter. To capture it efficiently, carbon needs a well-developed micropore network in that size range. Coconut shell carbon delivers exactly that: fine, uniform micropores concentrated below 2 nm, with surface area typically 1100-1300 m²/g.
Coal-based and wood-based carbons have wider, more mesoporous structures — fine for decolorizing liquids, less effective for trapping the small gold complex. That is why gold plants worldwide standardize on coconut shell, despite the higher price per ton.
2. The Two Numbers That Matter: Iodine and Hardness
Iodine number (mg/g) measures total surface area/activity. Gold grade: 1000-1300. It tells you how much gold the carbon can hold, but it does not tell you how long the carbon survives.
Hardness (%) measures resistance to attrition. Gold carbon is abused daily: screened, pumped, eluted, regenerated. Soft carbon grinds into fines, and fines carry adsorbed gold out of the circuit with the pulp — what Malian operators call "running gold". This is the most expensive hidden loss in a gold plant. Gold grade: 95% minimum; for CIL plants in West Africa we stably supply 98%+ ball-pan hardness (ASTM D3802), with a de-plating (platelet-free) screening step that cuts initial fines. Hardness is measured by the ball-pan method (ASTM D3802): a 100 g sample is tumbled with steel balls for a fixed time and the fraction retained on the reference sieve is reported as % hardness. Coconut shell gold-grade carbon typically tests 96-99%, while many coal-based grades sit at 90-95% — that gap shows up directly in your make-up consumption.
Rule: compare iodine and hardness together. A carbon with iodine 1100 but hardness 90% will cost you more in gold-in-fines than a 1000/95%+ carbon saves you on price.
3. Mesh Size and Particle Distribution
Most gold circuits run 6x12 mesh (1.70-3.35 mm) or 8x16 mesh, plus 3x6 mm for larger columns. The choice depends on your interstage screens and elution column design. Verify the mesh distribution (ASTM D2862) of the actual delivered lot — blended or mis-screened lots behave unpredictably in screens and columns, and high platelet content clogs interstage screens.
4. How Much Carbon Do You Need?
CIL circuits typically run 15-25 g/L carbon concentration. Initial charge and make-up depend on throughput, ore grade, attrition and regeneration practice. A 2,000 t/d plant might carry 20-40 tonnes of carbon in circuit with monthly make-up of 2-5% depending on hardness and regeneration. Ask your supplier for a consumption model based on your specific circuit — a good supplier will calculate this with you. In plant practice, make-up (fresh) carbon in CIP plants commonly runs 20-100 g per tonne of ore — softer carbon pushes consumption to the top of that band.
5. Regeneration: Getting More Life From Your Carbon
Loaded carbon is stripped (elution), then thermally regenerated. Each thermal regeneration cycle typically removes 5-15% of carbon mass (5-10% is the commonly cited working range) through attrition, fines and handling loss. A well-run regeneration — acid wash first, then steam at 650-850°C in a rotary kiln — restores roughly 90-95% of virgin adsorption capacity, and coconut shell carbon in gold duty commonly survives 8-15 regeneration cycles before replacement. Coconut shell carbon with hardness 98%+ survives many cycles (typically 10-30+). Soft carbon loses activity fast and needs replacement. Track your regenerated carbon's iodine recovery — if it drops, check kiln temperature and cycle time before buying more carbon.
5b. Packing and Inland Logistics for West Africa
For inland destinations like Mali, packaging and delivery terms matter as much as the carbon itself. Standard export packing: 25 kg PP bags or 1 MT jumbo bags with an inner PE liner, palletized and shrink-wrapped against moisture on the long sea and road haul.
For Mali specifically: carbon is usually routed via Abidjan (Côte d'Ivoire) or Dakar (Senegal), then trucked inland to Bamako or the mine site. Ask your supplier for DAP (Delivered at Place) or CPT Bamako capability — and confirm the packing is moisture-proof double-layer (inner liner + jumbo bag) so the carbon arrives dry and intact. Ask the same questions we would: what moisture do you guarantee on arrival, and who handles the inland customs and trucking?
6. Troubleshooting: When Recovery Drops or Consumption Rises
If recovery falls with no ore change, check in order: 1) preg-robbing ore (see our poisoning guide); 2) fouling vs true poisoning (acid-wash iodine test); 3) carbon hardness/batch; 4) screens; 5) contact time. If consumption rises, check hardness, batch consistency, screens, regeneration and accounting (see our consumption guide).
Before you chase the carbon, know the numbers a well-run circuit should deliver. In a correctly operated CIP/CIL circuit, the carbon train typically recovers 95-99.5% of dissolved gold per contact series; barren solution usually runs 0.01-0.02 mg/L Au, and overall plant recovery (ore to bullion) typically lands in the 90-97% band. Typical gold loading on carbon before elution is 3,000-10,000 g Au/t (0.3-1.0% by mass); high-grade circuits can reach 8-12 kg/t.
| Parameter | Typical range |
|---|---|
| Carbon adsorption per contact series | 95-99.5% of dissolved gold |
| Barren solution | 0.01-0.02 mg/L Au |
| Overall plant recovery (ore to bullion) | 90-97% |
| Gold loading before elution | 3,000-10,000 g Au/t (0.3-1.0% by mass) |
| High-grade circuits | 8-12 kg/t |
7. Supplier Verification: The Five Checks
1. Real factory? Plant address, live video tour, visits welcome. A genuine factory has nothing to hide.
2. COA for the exact lot? Test the delivered batch yourself — not the brochure sample.
3. Hardness and ash on the actual batch? These two numbers explain most of the price difference. Ask for the test methods used (ASTM D3802 hardness, ASTM D2862 mesh) so you can compare apples to apples.
4. Raw material source? Coconut shell from Philippines/Indonesia is the gold standard for density and hardness.
5. Side-by-side testing? A confident supplier will run a parallel lab test against your current carbon — iodine, hardness, gold adsorption. This is the ultimate verification.
Put the Guide to Work: Test Our Carbon Against Yours
YELI Carbon is a coconut shell activated carbon factory in Longyan, Fujian — 20+ years, gold-grade lines, iodine 1000-1300, hardness 98%+ (98% available), COA with every batch, Philippine/Indonesian raw material. Send us a sample of your current carbon and we will run a side-by-side lab test: iodine, hardness, gold adsorption. See the real gap before you order.
Request a Sample Test →The Bottom Line
Gold recovery carbon is coconut shell GAC: iodine 1000-1300, hardness 98%+, 6x12 mesh or 3x6 mm. Compare suppliers on life-cycle cost and verifiable facts — not brochure numbers. The supplier that welcomes independent testing is the one worth your container order.
FAQ: Gold Recovery Carbon
Coconut shell granular activated carbon (GAC) is the industry standard for CIP/CIL gold recovery. It has the fine micropore structure (1-2 nm) sized for the gold cyanide complex, hardness of 95%+ (98%+ stably available for Mali-grade CIL duty) that resists attrition — so fines don't carry gold out of the circuit — and low ash for stable regeneration. Typical spec: iodine 1000-1300 mg/g, hardness 98%+ available, 6x12 / 8x16 mesh or 3x6 mm.
For gold CIP/CIL, look for iodine 1000-1300 mg/g. Iodine measures surface area/activity, but it is not the only number: hardness matters just as much (95%+), because soft carbon makes fines that carry adsorbed gold out of the circuit. Compare iodine and hardness together, not iodine alone.
Most gold plants use 6x12 mesh or 3x6 mm coconut shell GAC. The mesh must suit your interstage screens and elution column. Too coarse wastes capacity; too fine risks breakthrough through screens. Confirm mesh distribution on the actual delivered lot, not just the datasheet.
Check five things: 1) is it a real factory (plant address, live video tour, visit welcome); 2) COA for the exact delivered lot (test it yourself in a lab); 3) hardness and ash on the actual batch, not the brochure; 4) raw material source (coconut shell from Philippines/Indonesia is the gold standard); 5) willingness to run a side-by-side sample test with your current carbon. A genuine factory welcomes verification.
In a correctly operated CIP/CIL circuit, the carbon train typically recovers 95-99.5% of dissolved gold per contact series, with barren solution usually running 0.01-0.02 mg/L Au; overall plant recovery (ore to bullion) typically lands in the 90-97% band. Carbon is one link in the chain — pulp density, contact time, screens and elution all have to be right for those numbers to hold. If you want certainty for your ore, send us a sample and we will run a side-by-side bottle-roll test on your own pulp and solution.