Double refractory gold ores present significant processing challenges due to the presence of both sulfide minerals and carbonaceous matter, the latter of which adsorbs Au(CN)₂^- and reduces gold extraction efficiency. Traditional methods for carbonaceous matter treatment, such as roasting, can be environmentally harmful due to the emission of toxic byproducts (SO_x and As₂O₃). This study explores an eco-friendly enzymatic biotreatment approach using laccase, a multicopper enzyme functioning as an oxygen oxidoreductase, to degrade carbonaceous matter.

The objective of this research was to assess the potential of laccase-driven biotreatment to improve gold extraction, using 1-hydroxybenzotriazole hydrate and violuric acid monohydrate as mediators to enhance enzymatic activity. The process was evaluated by investigating mediator sorption characteristics and gold extraction efficiency. Carbonaceous matter degradation was observed using CHN elemental analysis, Raman spectroscopy, three-dimensional fluorescence spectrometry, and thermogravimetry.

Results indicated that mediator-enhanced laccase treatment significantly improved the degradation of carbonaceous matter, leading to a higher gold extraction rate compared to treatments without mediators, with voluric acid monohydrate showing superior performance. This research highlights the potential of laccase-mediated biodegradation as a sustainable alternative for gold extraction, offering both environmental benefits and promising processing efficiency—especially in the context of carbon science within biohydrometallurgy.