EFFECT OF OPERATION PARAMETERS ON GOLD AND SILVER ELUTION FROM
ACTIVATED CARBON
Driss Mrabet1, Claude Gagnon1, Caroline Olsen1, Renée Dupéré2, Jean Châteauneuf2.
1
COREM, 1180, rue de la Minéralogie, Québec (QC) G1N 1X7 Canada
2
Canadian Malartic, 100, chemin du Lac Mourier, Malartic, (QC) J0Y 1Z0 Canada
ABSTRACT
In a CIP/CIL circuit, elution parameters of adsorbed precious metals on activated carbon are not rigorously
determined and are often based on previous experience, which leads to a non-optimal operation. In addition,
optimization of desorption operation in plant is difficult. To gain more insight about the influence of
different parameters of elution and behaviour of adsorbed precious metal toward these parameters,
COREM carried out laboratory scale tests on industrial loaded carbon samples.
Influence of parameters such as flowrate, pressure, temperature and NaCN and NaOH concentration were
studied using a laboratory scale elution column developed at COREM. Regarding eluent flowrate, results
showed that desorption kinetic flowrate can be increased above the generally accepted level (2 -2.5 BV/h)
resulting in high performances in terms of precious metal extraction, shorter cycle time and low cyanide
degradation. The investigation revealed differences in behaviour between gold and silver. While the impact
of elution parameters on gold desorption is mainly kinetic, silver can undergo an irreversible chemical
transformation onto the carbon surface during elution resulting in poor silver extraction. XPS carbon
surface analysis revealed the presence of reduced silver and strong organometallic bonded silver species.
Weak silver desorption performances are more significant for high silver loaded carbon and does not
exceed 70%. Parameters regarding eluent high flowrate were implemented at Canadian Malartic plant
leading to stable and high metal extraction performance and reduction of elution cycle time which was a
bottleneck in production. However, such circuit design and equipment do not generally allow
implementation of higher eluent flowrate without modifying preheating exchanger and electrowinning
capacity. These results show that these aspects should be reconsidered during the design of an elution
circuit.
KEYWORDS
CIL, CIP, Gold, Silver, Activated Carbon, Elution, Canadian Malartic