Abstract
As high-grade, easily treatable gold deposits become increasingly depleted, the gold industry is seeking alternative pretreatment technologies to improve extraction efficiency, increase throughput, and reduce reagent consumption for the processing of lower-grade, more complex ores. Beyond enabling the processing of lower-grade ores, these improvements may significantly enhance the overall economic performance of the processing circuit.
The Microwave pretreatment has been widely investigated in mineral processing as a method to improve comminution performance by weakening ore particles, promoting microfracturing, and reducing grinding energy requirements. Most of the existing research has focused on the comminution-related benefits, particularly the microwave-induced fractures to make ores easier to crush or grind, with the focus on energy saving for the subsequent comminution step. However, limited attention has been given to how microwave pretreatment affects downstream processing performance, including mineral liberation, leaching behaviour, reagent consumption, and overall gold recovery.
This research focuses on the application of microwave pretreatment to refractory gold ores where gold is often finely disseminated and locked within sulphide minerals, which hinders cyanidation. In these ores, improving downstream extraction depends not only on reducing particle size, but also on increasing the accessibility of gold and modifying the mineral structure in a way that benefits subsequent processing.
The study examines the influence that selective heating, thermal stress generation, and mineral-boundary cracking have on gold processing outcomes. Particular attention is given to identifying the conditions under which microwave pretreatment can improve leaching kinetics and gold recovery without causing negative effects such as passivation, sintering, or inefficient energy use.
This will be assessed by comparing the leaching response of the treated and untreated materials, gold recovery, reagent consumption, and the relationship between microwave energy input and downstream processing performance. This approach allows the value of microwave pretreatment to be evaluated beyond grinding energy savings alone.
By shifting the focus from comminution to the downstream response of refractory gold materials, this work aims to better define the practical value of microwave pretreatment as part of an integrated mineral processing flowsheet. The goal is to evaluate how microwave treatment can improve the processing of complex gold ores in ways that extend beyond comminution energy savings, potentially creating greater economic value through improved downstream efficiency.