Gold Recovery with Activated Carbon

How carbon recovers gold

In cyanide leaching, gold dissolves as a gold-cyanide complex. Activated carbon adsorbs that complex onto its internal pore surface, concentrating the gold onto the carbon — which is then eluted and the gold recovered, while the carbon is regenerated for reuse. The carbon works in three classic circuit positions:

• CIP — carbon-in-pulp: carbon moves counter-current to the leached pulp in a series of agitated tanks, each separated by screens that hold the carbon back while pulp flows on.
• CIL — carbon-in-leach: carbon is added directly into the leaching tanks, so leaching and adsorption run simultaneously in the same vessels.
• Heap leaching: leach solution percolates through a heap of ore, and the pregnant solution passes through carbon adsorption columns to strip the gold.

Every one of these duties puts the carbon under mechanical stress — agitated tanks, screen transfer, slurry abrasion. That is why gold-recovery carbon is graded on its hardness and attrition resistance first: carbon that breaks down is lost through the screens, and gold is lost with it.

Selection checklist

• Hardness and attrition — the decisive property for agitated circuits. Carbon loss through screens is direct gold loss; specify the hardness test method and the attrition limit.
• Activity — the gold-loading rate on a reference solution. Compare activity figures only when the test method and reference conditions match.
• Particle size distribution — sized to your screens: oversize fouls the inter-stage screens, undersize is lost to the pulp.
• The elution loop — carbon leaves the circuit loaded, comes back regenerated. State your elution and thermal reactivation route; it sets the carbon's minimum durability.

Technical background: adsorption mechanism and regeneration in our knowledge center.