# Gold Recovery Rate Dropping: Is It Your Ore or Your Activated Carbon?

> Source: https://www.yelicarbon.com/blog-gold-recovery-dropping-ore-or-carbon.html

Recovery is slipping but ore looks the same. Before you blame the carbon — or the ore — run this field checklist to find the real cause.

[Gold recovery rate diagnosis in CIL plant]

**By the YELI Technical Team** · Updated August 2026 · 7 min read

**Short answer:** When gold recovery drops and ore grade looks unchanged, check in this order: 1) carbon activity — is the carbon in the tanks actually loading gold (test loaded carbon or regenerated iodine); 2) carbon concentration per tank — is it at design level; 3) carbon fines — are fines carrying gold out of the circuit; 4) contact time — did pulp flow change; 5) ore variability — even "same ore" changes from zone to zone. In our experience, carbon-related causes (activity, concentration, fines) account for most sudden drops, and they are fixable within days once identified.

Recovery rate is the number the plant manager watches every day. When it drifts down and the ore looks the same, the instinct is to blame either the ore or the carbon — and both instincts can be wrong. The cause is usually one specific link in the chain, and finding it is a matter of method, not guesswork. Here is the field checklist we run.

## Step 1: Is the Carbon Actually Loading Gold?

The first question is not "is the carbon good" but "is this carbon loading gold right now." Test the loaded carbon in the first tank — if gold loading is normal, the carbon is working and the problem is downstream (elution or recovery of loaded carbon). If loading is low, the carbon may be exhausted, poisoned or too low in concentration.

## Step 2: Carbon Concentration Per Tank

Most CIL circuits run 15–25 g/L of carbon. If concentration has drifted down — make-up lagged, or losses exceeded additions — contact time with carbon drops and recovery follows. Simple to check, simple to fix: bring concentration back to design.

## Step 3: Carbon Fines — The Silent Gold Leak

Fines are the most underrated cause of recovery loss. Soft carbon grinds into fines that escape the screens carrying adsorbed gold — the gold is "recovered" onto carbon that then leaves the circuit. Test for fines in the pulp and check screen efficiency. This connects directly to carbon hardness: harder carbon (95%+) generates fewer fines.

## Step 4: Contact Time and Pulp Flow

If throughput changed, or a tank's mixing degraded, effective contact time falls even though the circuit "looks the same." Check retention time against design and look for channeling or dead zones.

## Step 5: Ore Variability — Honest Check

Even "the same ore" varies by zone, grind and oxidation state. If all carbon checks pass, run ore samples through a lab leach to compare heads and recoverable grade. Sometimes it really is the ore — and knowing that saves you from changing carbon that isn't the problem.

## Step 6: When It IS the Carbon — What to Do

If activity, hardness or consistency is the culprit, the fix is a controlled comparison, not a leap of faith: take a sample of your current carbon and a sample of a candidate replacement, and run them side-by-side — iodine, hardness, gold adsorption. See the real gap before you switch suppliers. That is the difference between gambling on a price and verifying a performance.

### Run a Side-by-Side Carbon Test With Us

YELI Carbon is a coconut shell activated carbon manufacturer in Longyan, Fujian — 20+ years, gold-grade lines, hardness 98%+ (98% available), COA with every batch. Send us a sample of your current carbon and we will run iodine, hardness and gold adsorption against ours. You see the real difference before ordering.

Start a Sample Comparison → (https://www.yelicarbon.com/contact.html#quote-form)

## The Bottom Line

Recovery drops have a cause, and it is usually findable in a day of systematic checking: carbon activity, concentration, fines, contact time, then ore. Rule out each in order and you will not waste money changing the wrong thing. For deeper reading, see our CIP/CIL carbon guide (https://www.yelicarbon.com/blog-gold-cip-cil.html) and hardness guide (https://www.yelicarbon.com/blog-why-carbon-hardness-matters-gold-recovery.html).

## FAQ: Gold Recovery Rate Drops

Gold recovery dropped but ore looks the same — is it the carbon? +
Check carbon activity first: is the carbon in the tanks actually loading gold? Then carbon concentration per tank (15-25 g/L design), carbon fines carrying gold out of the circuit, and contact time. Carbon-related causes account for most sudden drops and are fixable within days once identified.

How do I know if my carbon is exhausted or poisoned? +
Test the loaded carbon in the first tank. If gold loading is low, the carbon may be exhausted (activity spent), poisoned (organic or chemical fouling), or too low in concentration. Test regenerated carbon iodine and compare to spec to separate exhausted from poisoned.

Can carbon fines really cause recovery loss? +
Yes. Fines escape the interstage screens carrying adsorbed gold out of the circuit — the gold is recovered onto carbon that then leaves. Softer carbon generates more fines. This is why hardness (95%+) matters as much as iodine value in gold duty.

How do I compare a new carbon supplier before switching? +
Run a side-by-side lab test: take your current carbon and the candidate, test iodine, hardness and gold adsorption together. That shows the real gap before you commit — better than comparing FOB prices on paper.

### Related reading

- Why Coconut Shell Carbon Dominates Gold CIP/CIL (https://www.yelicarbon.com/blog-gold-cip-cil.html)

- Why Carbon Hardness Matters (https://www.yelicarbon.com/blog-why-carbon-hardness-matters-gold-recovery.html)

- Carbon Dosage in CIL Plants (https://www.yelicarbon.com/blog-activated-carbon-dosage-cil-plant.html)

- Why Carbon Consumption Suddenly Increased (https://www.yelicarbon.com/blog-why-carbon-consumption-increased-cil.html)

- Gold CIP/CIL Grade Activated Carbon (https://www.yelicarbon.com/product-gold-cip-cil.html)

Browse all products & request a quote → (https://www.yelicarbon.com/products.html)