# Why Did My CIL Plant Carbon Consumption Suddenly Increase? A Field Diagnosis Guide > Source: https://www.yelicarbon.com/blog-why-carbon-consumption-increased-cil.html Your make-up carbon bill jumped last month and you don't know why. Here is the field diagnosis we walk plants through — in order, with the numbers to check. [CIL plant carbon consumption diagnosis] **By the YELI Technical Team** · Updated August 2026 · 7 min read **Short answer:** When CIL carbon consumption suddenly rises, check five things in order: 1) delivered carbon hardness — softer carbon becomes fines faster, and fines carry gold out; 2) batch consistency — did the last delivery actually match the COA; 3) screen efficiency — broken screens let carbon escape with the pulp; 4) regeneration practice — kiln temperature or cycle changes; 5) your make-up accounting. In most plants we see, the cause is a combination of one bad batch (hardness below spec) and screen wear — not a sudden change in the circuit itself. Carbon consumption in a CIP/CIL plant is not supposed to spike. If your make-up tonnage jumped without a change in ore throughput or grade, something changed in the carbon loop — and finding it fast saves both money and recovered gold. This guide gives the field diagnosis we walk plants through, in the order that catches the most problems first. ## Step 1: Check the Hardness of Your Current Carbon Hardness is the number that quietly controls consumption. If the carbon in your circuit is softer than the spec you ordered, it grinds into fines every time it is screened, pumped and eluted — and fines are exactly what carries adsorbed gold out of the circuit. A drop from 97% to 92% hardness can double attrition losses over a few months. **What to do**: Pull a sample of the carbon currently in your circuit, run an abrasion test, and compare against the COA of the last delivery. If hardness is below 95%, that is your likely culprit. ## Step 2: Verify the Last Batch Actually Matched Its COA This is the "sample vs bulk" trap. The sample you approved may have tested perfectly, but the delivered lot can be different — lower hardness, different mesh distribution, or blended with cheaper feedstock. This is the most common reason consumption jumps right after a new delivery. **What to do**: Take a sample from the delivered lot itself (not the brochure), test iodine, hardness and mesh distribution in your own or an independent lab, and compare against the COA that shipped with that exact batch. ## Step 3: Check Screen Efficiency Broken or worn interstage screens let carbon escape with the pulp. The symptom is often invisible for weeks — you just see consumption creeping up and tailings grade rising. Walk the tanks and inspect the screens, especially after a high-wear period. **What to do**: Check for carbon in the tailings, inspect screen apertures, and measure fines in the circuit. Screens are a mechanical cause that no amount of carbon quality fixes. ## Step 4: Review Regeneration Practice If your kiln temperature drifted, or cycle time changed, regeneration losses can climb. Overheating burns off carbon; under-heating leaves activity low so you add more make-up to compensate. Both look like "consumption went up" on paper. **What to do**: Log kiln temperature and cycle time for the last two months, and test regenerated carbon activity (iodine) to see if it is recovering properly. ## Step 5: Audit Your Make-up Accounting Sometimes consumption didn't actually rise — the accounting did. If weighing, logging or inventory counting slipped, the "increase" is a paperwork artifact. Worth ruling out before you chase a carbon problem that isn't there. ## Step 6: Compare Against the Full Life-Cycle, Not Just FOB Price Here is the uncomfortable truth: the cheapest carbon per ton is often the most expensive per ounce recovered. A carbon that is $200/t cheaper but 3% softer will cost you more in make-up tonnage and gold-in-fines than you saved on the invoice. When you compare suppliers, ask for hardness and ash on the actual lot, and run a side-by-side lab test with your current carbon before you switch. ### We Help Plants Diagnose Consumption Problems 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. If your consumption climbed, send us a sample of your current carbon and we will run a side-by-side test against ours: iodine, hardness, gold adsorption. See the real gap before you order. Request a Sample Test → (https://www.yelicarbon.com/contact.html#quote-form) ## The Bottom Line Sudden carbon consumption increases almost always come from one of five places: delivered hardness, batch consistency, screens, regeneration, or accounting. Diagnose in that order, and compare suppliers on life-cycle cost — not FOB price. For the full picture on hardness, see our hardness guide (https://www.yelicarbon.com/blog-why-carbon-hardness-matters-gold-recovery.html), and for make-up calculation, this consumption guide (https://www.yelicarbon.com/blog-how-much-activated-carbon-for-gold-recovery.html). ## FAQ: CIL Carbon Consumption Problems Why did my CIL plant carbon consumption suddenly increase? + Check five things in order: delivered carbon hardness (softer carbon = more fines carrying gold out), batch consistency (did the last lot match its COA), screen efficiency (broken screens let carbon escape), regeneration practice (kiln drift), and make-up accounting. In most cases it is one bad batch plus screen wear. How do I test if my delivered carbon is lower hardness than ordered? + Run an abrasion test on a sample from the delivered lot and compare against the COA. Hardness below 95% is a red flag for gold duty. Also verify mesh distribution — blended or mis-screened lots behave differently in your screens and elution column. Can a bad carbon batch really cause gold loss? + Yes. Soft carbon grinds into fines during screening, pumping and elution, and those fines carry adsorbed gold out of the circuit with the pulp. A hardness drop from 97% to 92% can roughly double attrition losses and the gold lost in fines over a few months. Should I compare suppliers on FOB price or total cost? + Total cost. A carbon that is $200/t cheaper but softer will cost more in make-up tonnage and gold-in-fines than the invoice saving. Ask for hardness and ash on the actual lot, and run a side-by-side lab test with your current carbon before switching. ### Related reading - Why Carbon Hardness Matters in Gold Recovery (https://www.yelicarbon.com/blog-why-carbon-hardness-matters-gold-recovery.html) - How Much Activated Carbon Do You Need? (https://www.yelicarbon.com/blog-how-much-activated-carbon-for-gold-recovery.html) - Activated Carbon Dosage in CIL Plants (https://www.yelicarbon.com/blog-activated-carbon-dosage-cil-plant.html) - How to Verify a Carbon Supplier (https://www.yelicarbon.com/blog-verify-activated-carbon-supplier.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)