In carbon-in-pulp (CIP) gold recovery, pellet activated carbon is used to adsorb dissolved gold-cyanide complexes from a cyanidation slurry. The loaded carbon is separated from the pulp, washed, eluted, and then sent for gold recovery by electrowinning or smelting. Although granular activated carbon is more common in many CIP plants, pellet carbon can be considered when its adsorption performance, mechanical strength, particle size, and screening behavior match the plant design. At Zhengying, I help buyers evaluate carbon based on the complete recovery circuit rather than shape alone.
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During cyanide leaching, gold is converted into a soluble gold-cyanide complex. Activated carbon provides a porous surface that adsorbs this complex from the liquid phase while the ore slurry remains in a series of agitated tanks. The carbon is then transferred counter-currently or in a controlled sequence so that fresh or regenerated carbon contacts the lowest-gold slurry and loaded carbon moves toward the front of the circuit.
The carbon does not dissolve gold, replace cyanide leaching, or directly refine bullion. Its role is selective adsorption after gold has entered solution. For this reason, carbon selection must be coordinated with ore mineralogy, cyanide concentration, slurry solids, pH, temperature, screen design, and elution conditions.
Pellet carbon may be charged into CIP adsorption tanks where it contacts gold-bearing pulp under continuous agitation. The particle size must be large enough for the interstage screens to retain it and resistant enough to avoid excessive breakage. A commonly evaluated carbon size range is approximately 6–20 mesh, but the correct range depends on screen openings, slurry characteristics, and plant operating practice.
After adsorption, carbon is screened from the slurry and transferred to a loaded-carbon storage or elution circuit. Pellet geometry can influence flow, bulk density, screen retention, and transfer behavior. I recommend evaluating carbon loss through screen apertures and carbon fines generation during pumping or air lifting, rather than relying only on the nominal particle size.
Loaded carbon is commonly washed and treated in an elution circuit to remove the adsorbed gold. The stripped carbon may then be thermally regenerated and returned to service if its pore structure and mechanical properties remain acceptable. Pellet carbon should therefore be assessed not only for fresh-carbon adsorption capacity but also for resistance to repeated washing, heating, abrasion, and handling.
Pellet activated carbon is manufactured by forming powdered or fine carbonaceous material into cylindrical or shaped particles, followed by activation and sizing. Coal, wood, coconut shell, and other feedstocks can produce different pore structures, ash levels, hardness, and adsorption profiles. No single raw material is automatically best for every gold plant, because the final performance depends on activation conditions and the specific gold-bearing solution.
| Specification | Why It Matters in CIP | What I Recommend Checking |
|---|---|---|
| Particle size | Controls screen retention, contact behavior, and carbon transfer | Size distribution, fines percentage, and compatibility with interstage screens |
| Adsorption capacity | Influences gold loading and carbon inventory requirements | Gold adsorption testing using representative process solution |
| Hardness and abrasion resistance | Reduces carbon loss and fines formation during circulation | Hardness, abrasion index, and post-handling particle integrity |
| Ash and soluble impurities | May affect elution, regeneration, and process cleanliness | Ash content, water-soluble extractables, and consistency between batches |
| Pore structure | Determines access to dissolved gold species and competing compounds | Iodine number or other relevant adsorption tests, interpreted with process data |
Gold CIP circuits commonly operate at an alkaline pH, often around 10–11, to control cyanide chemistry and process safety. However, pH alone does not predict carbon performance. Organic matter, copper, silver, preg-robbing minerals, and other dissolved species may compete with gold for adsorption sites, so laboratory testing with actual or representative slurry is more meaningful than a generic specification sheet.
I first review slurry density, residence time, tank configuration, carbon concentration, gold grade in solution, cyanide conditions, pH, temperature, and screen arrangement. These details identify the mechanical and adsorption requirements that the carbon must meet. A carbon that performs well in a clean laboratory solution may behave differently in a high-solids or contaminant-rich plant slurry.
Screen retention is a practical decision point because carbon loss can directly affect operating cost and gold accounting. I compare the pellet size distribution with the interstage screen aperture and inspect the expected amount of undersize material. The target is not simply a large particle; it is a stable particle that remains mobile enough for transfer while being reliably retained by the screen.
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I recommend batch or column testing using representative pregnant solution or slurry whenever possible. The test should examine adsorption rate, equilibrium loading, gold selectivity, and the response of the loaded carbon during stripping. If a buyer has an established elution recipe, the carbon should be evaluated under those same conditions instead of being judged only by a general iodine number.
The purchase price per tonne is only one part of the decision. A lower-cost carbon can become uneconomical if it generates excessive fines, requires frequent top-up, loads poorly, or loses performance quickly after regeneration. I therefore compare fresh-carbon consumption, expected carbon loss, regeneration frequency, gold loading, elution efficiency, and delivery reliability.
Pellet carbon can offer consistent formed particles, useful bulk handling characteristics, and a geometry that may suit specific adsorption or filtration equipment. Its cylindrical form can also be manufactured within controlled size ranges when the production process is properly managed. These benefits are relevant when a plant has a defined screen design and requires consistent carbon movement.
However, pellet carbon is not automatically superior to granular carbon in CIP. Shape, density, pore structure, hardness, and fines behavior can vary substantially between suppliers and production batches. Some pellet products may not fit existing CIP screens, pumps, transfer methods, or regeneration equipment without modification, so compatibility testing is essential before a full-scale change.
Another frequent mistake is treating fresh carbon performance as the complete solution. In a CIP circuit, carbon is exposed to repeated abrasion, slurry transport, washing, stripping, and heating. I encourage buyers to request a technical data sheet, particle-size analysis, hardness or abrasion information, ash data, packaging details, and a documented sampling plan before approving a supply program.
At Zhengying, I support industrial buyers with carbon selection for gold recovery, including product specification review, particle-size matching, sample coordination, packaging discussion, and export supply planning. I do not treat a catalog value as a guaranteed plant result; instead, I recommend confirming performance against the buyer’s slurry and operating conditions. This approach helps reduce the risk of selecting a carbon that looks suitable on paper but performs poorly in the actual CIP circuit.
For an initial technical review, I typically ask for the intended application, existing carbon type, particle-size requirement, screen aperture, slurry conditions, approximate gold concentration, elution method, monthly consumption, and destination port. If plant data are limited, a conservative trial order and controlled comparison can provide more useful evidence than an immediate bulk purchase. Packaging and shipment planning can then be aligned with storage conditions, handling equipment, and the required delivery schedule.
Pellet activated carbon is used as the adsorption medium that captures dissolved gold from cyanide leach slurry in a CIP gold recovery process. Its value is determined by how effectively it adsorbs gold, remains on the correct side of the screens, withstands circulation, releases gold during elution, and retains performance after regeneration. Pellet form alone is not a guarantee of better recovery, so the product must be matched to the complete plant circuit.
My recommended next step is to collect your CIP operating data and compare a controlled pellet-carbon sample with the carbon currently in use. Zhengying can help review the required specifications, arrange suitable sample quantities, and develop a practical supply proposal for your application. Contact our technical sales team with your carbon size, screen design, process conditions, and estimated demand so we can recommend a responsible starting point.
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