112 Tons Coconut Shell Carbon Shipped to Tanzania for Gold CIL
A Tanzania-based gold mining operation needed 112 tons of coconut shell activated carbon for their CIL (carbon-in-leach) circuit. Their core concern: the aggressive agitation conditions in their tanks were destroying carbon too fast — high attrition loss, frequent top-ups, and inconsistent quality between shipments from previous suppliers.
We supplied the full 112-ton order in a single shipment, with batch-level COA documentation and container loading coordinated to meet their production schedule.
Client Requirements and Pain Points
The mine's processing team outlined three problems they'd been dealing with:
| Problem | Impact on operations |
|---|---|
| Carbon breaking
apart in agitated tanks |
Fines passing through
screens → gold loss to tailings |
| High attrition rate
(previous supplier: ~3% per cycle) |
Frequent carbon top-ups,
increased cost per ounce recovered |
| Quality inconsistency
between batches |
Unpredictable gold loading,
harder to optimize elution timing |
Their spec requirement was clear: they needed carbon that could survive 15+ adsorption-elution cycles without significant degradation, with consistent performance from the first ton to the last.
Product Specification (As Delivered)
| Parameter | Specification | Test method |
|---|---|---|
| Raw material | Coconut shell | — |
| Mesh size | 6×12 (1.68–3.35 mm) | Sieve analysis |
| Iodine number | ≥1100 mg/g | ASTM D4607 |
| Hardness (ball-pan) | ≥98% | ASTM D3802 |
| Moisture | ≤5% | ASTM D2867 |
| Ash content | ≤3% | ASTM D2866 |
| Apparent density | 0.48–0.52 g/mL | ASTM D2854 |
| Gold adsorption activity (K value) | ≥28 mg Au/g C | In-house CIP simulation |
Why these numbers matter for gold mining:
- Hardness 98%+: In a CIL circuit, carbon tumbles in agitated slurry for 8–24 hours per cycle. Each percentage point of hardness above 95% translates to measurably longer carbon life. At 98%, our carbon typically survives 18–22 adsorption-elution cycles before reaching end-of-life screen size.
- Iodine 1100+: Higher microporosity means more active sites for gold-cyanide complex adsorption. This translates to higher gold loading per ton of carbon — which means fewer tons of carbon circulating in your system to recover the same amount of gold.
- Ash ≤3%: Low ash means less inorganic interference during thermal reactivation. High-ash carbons degrade faster through repeated reactivation cycles because minerals catalyze carbon oxidation at kiln temperatures.
Quality Control Process
Every shipment includes batch-level testing. For this 112-ton order (shipped across 5 containers), each container's carbon lot was tested separately:
- Pre-production: Raw coconut shell inspection (moisture, size, origin verification)
- Post-activation: Full parameter testing against spec sheet
- Pre-loading: Final QC check — iodine, hardness, moisture, mesh size distribution
- Documentation: COA issued per lot with test date, batch number, and operator ID
The client received 5 individual COAs — one per container — so they could track performance differences (if any) between lots during operation. This is standard practice for mining clients who run continuous CIL circuits and need to correlate carbon performance with specific batches.
Logistics and Shipping
| Item | Detail |
|---|---|
| Total volume | 112 tons |
| Packaging | 1-ton FIBC jumbo bags (double-lined) |
| Containers | 5 × 20ft |
| Loading port | Xiamen, China |
| Destination | Dar es Salaam, Tanzania |
| Transit time | ~15 days |
| Shipping terms | FOB Xiamen (client
arranged ocean freight) |
Scheduling consideration: Gold mines run 24/7. A production stoppage because carbon ran out costs far more than the carbon itself. We coordinated production timing so all 5 containers shipped within the same week — the client received the full 112 tons in one customs clearance cycle rather than staggered deliveries that would each require separate port handling.
Why Coconut Shell for Gold CIL (Not Coal-Based)
Some suppliers offer coal-based carbon at lower prices for gold recovery. Here's why most professional mining operations specify coconut shell:
| Factor | Coconut shell | Coal-based |
|---|---|---|
| Hardness | 98–99% | 95% |
| Attrition loss
per cycle |
0.5–1.5% | 2–4% |
| Gold loading
capacity |
Higher (more micropores) | Lower |
| Reactivation
cycles |
18–22 before
replacement |
8–12 before replacement |
| Cost per ton | Higher | Lower |
| Total cost of
ownership |
Lower (lasts longer,
less gold loss) |
Higher (frequent replacement
+ gold loss to fines) |
The upfront price difference between coconut and coal carbon is typically 30–40%. But when you factor in carbon life, gold loss from fines, and reactivation costs — coconut shell carbon usually costs less per ounce of gold recovered.
Results
After 6 months of operation with our carbon, the client reported:
- Attrition loss: ~1.2% per cycle (vs. 3%+ with previous supplier)
- Carbon life: on track for 20+ cycles
- Gold loading: consistent 4–6 kg Au per ton of carbon
- Batch consistency: all 5 container lots performing within ±3% of each other on key metrics
They've since placed a second order for the next production campaign.
Supply Capability for Gold Mining Operations
| Parameter | What we offer |
|---|---|
| Product | Coconut shell activated carbon, |
| Standard grades | 6×12mesh |
| Iodine number | 1050–1200 mg/g |
| Hardness | ≥98% premium |
| Monthly capacity | 700+ tons (across 2
production facilities) |
| Packaging | 25kg bags, 500kg bags, or
1-ton jumbo bags |
| Certifications | ISO 9001, COA per batch,
SGS/BV inspection available |
| Key markets served | Tanzania, Ghana, Sudan, Mali,
DRC, South Africa, Ethiopia |
We supply activated carbon to CIL/CIP gold operations across East and West Africa. If you're evaluating suppliers or looking to reduce carbon consumption costs, send us your current carbon spec or COA — we'll confirm if our product matches and arrange samples for your own plant trial.
FAQ
What mesh size activated carbon is used for gold CIL recovery?
6×12 mesh (1.68–3.35 mm) is the standard size for gold CIL and CIP circuits. This size provides the right balance between gold adsorption kinetics (smaller particles adsorb faster) and screen retention (larger particles don't pass through inter-stage screens). Some operations use 6×16 for finer ore slurries.
How long does coconut shell activated carbon last in a gold CIL circuit?
High-quality coconut shell carbon with hardness ≥98% typically survives 18–22 adsorption-elution-reactivation cycles before reaching minimum particle size for screen retention. Actual lifespan depends on agitation intensity, slurry abrasiveness, reactivation kiln conditions, and operating temperature.
What is a good gold loading rate for activated carbon in CIL?
Commercial CIL operations typically achieve 4–8 kg of gold per ton of activated carbon, depending on head grade, cyanide concentration, carbon concentration in the circuit, and residence time. Higher iodine number carbon (≥1100) generally achieves the upper end of this range under optimized conditions.
How much activated carbon does a gold mine need per month?
This depends on circuit size, gold throughput, and carbon attrition rate. A typical medium-scale CIL operation processing 3,000–5,000 tons of ore per day uses 50–150 tons of activated carbon in circulation, with monthly top-up requirements of 10–30 tons to replace losses from attrition and fine generation.
Can activated carbon be reactivated after gold elution?
Yes. After gold is stripped from the carbon through elution (hot caustic cyanide solution or Zadra process), the carbon is thermally reactivated at 700–850°C in a rotary kiln. This burns off organic contaminants and re-opens pore structure. Properly reactivated carbon recovers 90–95% of its original adsorption capacity.