# Running a CIP Carbon Circuit: 10 Operating Rules for Plant Teams

> Source: https://www.yelicarbon.com/blog-cip-circuit-operating-rules.html

CIP circuits rarely fail dramatically - they drift. Carbon concentration creeps, transfer becomes irregular, elution falls behind circulation, and six months later the plant buys 30% more carbon for the same recovery. These ten rules are the discipline that prevents it.

**By the YELI Technical Team - Updated October 2026 - 9 min read**

> **Short answer:** Ten operating rules carry most of the value in a CIP carbon circuit: measure loaded carbon daily; set carbon concentration from the adsorption profile rather than habit; transfer on a fixed schedule and record it; treat screens as a maintenance item; run a monthly fines balance; elute to match carbon circulation; acid wash on a trigger, not a calendar; verify eluent strength by analysis; keep a carbon balance that reconciles; and buy one specification from one supplier with a batch COA. None of them require new equipment.

CIP circuits rarely fail because of one dramatic event. They drift: carbon concentration creeps up, transfer becomes irregular, elution falls behind circulation, fines accumulate, and six months later the plant is buying 30% more carbon to hold the same recovery. These ten rules are the operating discipline that prevents the drift.

## 1. Measure loaded carbon every day

The loaded carbon assay is the single best indicator of whether the circuit is working. Daily measurement gives you a trend; weekly measurement gives you a surprise. Record loaded carbon grade, stripped carbon grade and the difference - that difference is what the column actually recovered.

## 2. Set carbon concentration from the profile, not from habit

Sample solution gold across the adsorption train and look at how the stages perform. Carbon concentration commonly sits in the 10-25 g/L range, held higher where the solution grade is highest. <em>(Industry-typical.)</em> If the last tank is doing almost nothing, the problem is concentration or residence time - not the carbon grade.

## 3. Transfer carbon on a fixed schedule, and record it

Counter-current transfer is what makes CIP work. Irregular transfer leaves the first tank overloaded and the last tank starved. Record transfer volume, timing and the batch number of any carbon added, so the circuit has a history you can read back.

## 4. Treat screens as a maintenance item

Blinding is progressive and quiet. Inspect on a fixed interval, keep a spare screen set, and check tailings oversize for fines and whole granules. A blinded screen distorts the whole adsorption profile, which then distorts every decision made from plant data.

## 5. Run a monthly fines balance

Count what you put in, what you take out, and what leaves as fines. If fines generation rises while incoming iodine stays flat, the problem is attrition - carbon hardness and handling - not adsorption capacity.

## 6. Elute to match carbon circulation

Loaded carbon waiting in a queue is gold sitting idle. Match elution and regeneration capacity to the rate at which carbon loads. Strips that run late force higher carbon concentration to compensate, which raises attrition, which raises consumption.

## 7. Acid wash on a trigger, not on a calendar

Acid washing is required when scale is present: strip times creeping up, whitish deposits on sampled carbon, hard water or high lime dosing. Washing on a fixed calendar wastes acid in soft-water circuits and misses the problem in hard-water ones.

## 8. Verify eluent strength by analysis

Eluent caustic and cyanide strength set the driving force for desorption. Recipes drift: make-up solution errors, dilution, dosing faults. Analyse rather than assume, especially when strips start running long. <em>(Eluent composition is industry-typical and plant-specific; confirm with your own metallurgical testwork.)</em>

## 9. Keep a carbon balance that reconciles

Carbon in, carbon out, inventory change, fines. If the balance does not close, either the inventory is wrong or carbon is leaving somewhere you have not measured. Either way, the gold balance will not close either.

## 10. One specification, one supplier, batch COA every time

Mixing suppliers with different hardness, sieve distribution and platelet content makes every operating variable harder to read. Standardise on one specification: 6x12 mesh coconut shell carbon, iodine 1000-1300 mg/g, hardness at least 98%, platelet content below 1.5%, COA on every batch.

## The ten rules in one table

| # | Rule | Cadence |
|---|---|---|
| 1 | Measure loaded and stripped carbon grade | Daily |
| 2 | Review carbon concentration against the adsorption profile | Weekly |
| 3 | Transfer carbon on schedule and record it | Daily/weekly |
| 4 | Inspect interstage screens | Weekly on rotation |
| 5 | Fines balance | Monthly |
| 6 | Match elution capacity to carbon circulation | Weekly |
| 7 | Acid wash assessment | Triggered |
| 8 | Analyse eluent strength | Weekly |
| 9 | Carbon balance reconciliation | Monthly |
| 10 | One specification, batch COA | Every lot |

## Frequently asked questions

**What is the most important daily measurement in a CIP circuit?**
Loaded carbon grade, and the difference between loaded and stripped carbon grade. That difference is the gold the elution circuit actually recovered, and a drifting trend shows up there before it shows up in the plant recovery figure.

**How often should carbon be transferred in a CIP plant?**
On a fixed schedule sized to the circuit's loading rate, with volumes and timing recorded. Irregular transfer - however well intentioned - leaves stages overloaded or starved and makes the plant data unreadable.

**Should carbon concentration be increased to improve recovery?**
Only if the adsorption profile shows the last stages are starved of carbon. Often the real constraint is residence time or insufficient elution capacity. Raising concentration to compensate increases attrition and carbon consumption without fixing the cause.

**How do I know if I need to acid wash?**
Trigger it on evidence: strip times creeping longer, whitish scale visible on sampled carbon, hard process water or high lime dosing. Calendar-based acid washing misses both directions.

**Why does carbon consumption creep up in a CIP circuit?**
Usually attrition, not adsorption: softer carbon, more transfer cycles, rougher pumping. Check fines generation and the incoming lot's hardness before buying a higher iodine grade.

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