Microwave Pretreatment of Carbonaceous Refractory Gold Ores Affected by Preg-Robbing: A Coupled Electromagnetic–Thermal Mechanism, Response-Surface Modelling and Multiobjective Optimization of Cyanidation Recovery
DOI:
https://doi.org/10.65093/aci.v17.n3.2026.62Keywords:
carbonaceous refractory ores, gold recovery, multiphysics optimization, mechanistic formulationAbstract
The depletion of free-milling gold deposits has shifted production toward carbonaceous refractory ores, where organic carbon re-adsorbs the Au(CN)− complex (preg-robbing), capping conventional cyanidation recovery at ~40%. This work reformulates the metallurgical challenge into a coupled multiphysics and optimization framework, evaluating microwave pretreatment to simultaneously induce thermal-stress micro-fracturing in the sulphide matrix and thermally passivate organic carbon. Two representative ores (MO-UG and STGO) were characterized through optical and scanning electron microscopy, XRD, fire assay, and atomic absorption. Factorial testing was analyzed via Spearman correlation, second-order response-surface modeling, shrinking-core/Arrhenius kinetics, Sobol sensitivity analysis, and NSGA-II Pareto optimization. Power correlates strongly with crack density (ρ = 0.92), while recovery correlates with crack density ((ρ = 0.74), temperature (ρ = 0.69), and organic carbon (ρ = 0.57). Above 600 °C, recovery exceeds 85%. Microwave pretreatment increases 48-hour recovery from 40% to 71.8%, reduces cyanide consumption, and enables a 33% throughput gain.
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