# How to Select Activated Carbon for Gold Recovery — A Buyer's Guide > Source: https://www.yelicarbon.com/blog-select-carbon-gold-buyers-guide.html Mesh size, iodine, hardness, moisture, COA verification, trial orders — and the hidden costs that decide your real price per tonne. [Selecting coconut shell activated carbon for a gold CIP/CIL plant] **By the YELI Technical Team** · Updated August 2026 · 8 min read Choosing activated carbon for a gold plant is not a purchasing exercise — it is a metallurgical decision with a monthly operating cost attached. The wrong carbon shows up slowly: lower gold loading, more fines in the elution column, more make-up carbon, and gold quietly leaving with the tailings. This guide walks through the decision in the order a buyer should think about it, from circuit parameters to the trial order. ## 1. Start With Your Circuit, Not the Brochure Before comparing suppliers, write down three numbers that your plant already knows: - **Screen / interstage aperture** — this fixes the carbon size you can run (typically 6x12 mesh or 3x6 mm). Changing size means changing screens, pumps and elution internals, so treat the cut as fixed. - **Carbon inventory and daily throughput** — how many tonnes of carbon you hold in circuit and how much you replace per month (typical attrition plus gold-room loss is 5-10% of inventory per month). - **Your target loading** — a high-grade circuit expects 8-12 kg gold per tonne of carbon; a low-grade one can live with less. Your elution schedule was designed around a loading rate. Armed with these three numbers, every specification question below becomes concrete instead of theoretical. ## 2. Read the Four Specs That Matter ### Iodine value (1000-1300 mg/g for gold duty) Iodine number is the most quoted figure on any datasheet, and it is a useful screening tool — but it is a proxy for adsorption capacity, not the target itself. For gold recovery, coconut shell GAC in the 1000-1300 mg/g band is the practical standard. The number to really watch is *consistency*: a supplier who ships one great batch and one mediocre batch is a bigger risk than a supplier with a slightly lower but stable figure. ### Hardness (95%+ for CIP/CIL) Gold carbon is screened, pumped, educted, stripped and roasted. Every move grinds it. Carbon below ~95% hardness turns to fines, and fines carry adsorbed gold out of the circuit, blind columns and inflate make-up purchases. Over a year, a 2% difference in attrition can be a tonne of carbon on a mid-size plant — at $2,000+/t for gold-grade GAC, that is the spec that pays for itself. ### Moisture (5% max, measured at loading) You pay freight on water. 5% moisture on a 20-tonne order is a tonne of water shipped at sea-freight rates. Confirm the measurement is taken at loading, not the figure on a certificate printed a month earlier. ### Ash (as low as practical) Low ash means less inert mass in your carbon charge and fewer impurities entering the pregnant solution. For gold circuits, ash under 5% is the norm; ask for it in the COA. ## 3. Coconut Shell vs Coal vs Wood — Keep It Simple For gold, the short answer is coconut shell: better micro-pore structure for gold cyanide adsorption, higher hardness, and predictable regeneration. Coal carbon is cheaper per tonne and works in some circuits, but the life-cycle math — attrition losses, slower kinetics, more frequent make-up — usually favours coconut shell. We covered the comparison in detail in Coconut Shell vs Coal Activated Carbon for Gold Recovery (https://www.yelicarbon.com/blog-coconut-vs-coal-gold.html). ## 4. Demand the COA of the Actual Lot The most common trap in this industry is comparing brochure numbers. A real factory will give you the Certificate of Analysis for the specific lot being shipped — not a template, not last quarter's average. Ask for it *before* you commit, and again with every shipment. If a supplier hesitates, that is your answer. ## 5. The Six-Step Sourcing Process That Works - **Send a spec-based enquiry** — mesh cut, target iodine and hardness, quantity per shipment, destination port. A professional supplier responds with a datasheet and a COA sample, not a price-only email. - **Verify the factory** — publish a plant address, accept a live video tour of kilns/screening/packing, and share export records. (See How to Verify an Activated Carbon Supplier From China (https://www.yelicarbon.com/blog-verify-activated-carbon-supplier.html).) - **Order a 25 kg evaluation bag at cost** — test it against the COA in your own lab: iodine, hardness, sieve analysis, moisture. - **Run a small plant trial** — one adsorption/elution cycle tells you more than any datasheet about loading, attrition and regeneration. - **Scale to a container** — 18-20 tonnes of coconut GAC in 25 kg bags fits a 20 ft container; agree on packing, palletising and shipping documents. - **Set a standing resupply** — most mining customers move to monthly or quarterly make-up orders so the circuit never runs short. > Buy carbon the way you buy ore: on measured, verifiable quality — not on the cheapest headline number. ## 6. The Hidden Costs That Decide the Real Price - **The cheap-tonne carbon** — a headline price 10% below market usually means lower iodine, lower hardness, or both. On a 30 t/year circuit, that 10% costs far more in gold losses and make-up than it saves. - **Water you paid freight on** — wet carbon is heavier, not better. - **Attrition you discover too late** — fines blind the elution column and bleed gold to tails; you find out after the order, not before. - **Size you cannot screen** — an off-cut shipment forces an unscheduled plant change. Ask for the full sieve analysis with every lot. ### Need Gold-Grade Carbon You Can Verify? We produce coconut shell GAC for CIP/CIL at our own plant in Longyan, Fujian — iodine 1000-1300, hardness ≥97%, moisture ≤5%, COA with every batch, live video tours and 25 kg evaluation bags at cost. Tell us your circuit size and we will recommend a grade and delivery plan. Request a Spec-Based Quote → (https://www.yelicarbon.com/contact.html#quote-form) ## The Bottom Line Selecting gold recovery carbon is a four-step exercise: fix the circuit parameters, read the four specs, verify the actual lot, and trial before you scale. Do that, and the monthly operating cost of your carbon sits where it should. Skip the verification, and the cheapest tonne in the market becomes the most expensive one you ever bought. ### Related reading - Gold Recovery Carbon: The Specs That Matter (https://www.yelicarbon.com/blog-gold-carbon-specs.html) - Coconut Shell vs Coal-Based Activated Carbon for Gold Recovery (https://www.yelicarbon.com/blog-coconut-vs-coal-gold.html) - How to Verify an Activated Carbon Supplier From China Is a Real Factory (https://www.yelicarbon.com/blog-verify-activated-carbon-supplier.html) Browse all activated carbon products & request a quote → (https://www.yelicarbon.com/products.html)