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<p>Gold heap leaching, responsible for nearly a third of global gold production, generates more than 500&#xa0;million tonnes of spent ore residue annually, resulting in multibillion dollar closure liabilities and persistent environmental risks. This article reviews the evolution of closure strategies over the past six decades, ranging from rinsing and capping to advanced store and release covers and predictive simulation models, with objectives such as contaminant control, cost reduction, and environmental protection. A systematic synthesis of the published literature confirms existing approaches remain dominated by a containment paradigm (defined as an approach that isolates waste from the environment using physical and chemical barriers without recovering embedded value) that treats residues as liabilities, offering only incremental improvements through bioremediation and geochemical stabilization. Hardly any closure methodology reframes residues as resources, despite their biological activity and enrichment with extremophilic consortia such as <i>Acidithiobacillus ferrooxidans</i>. Therefore, a valorization pathway that systematically recovers and commercializes these microbes as high performance inoculum for refractory gold bioleaching would constitute a pioneering step in mine closure practice. The target microorganism (<i>Acidithiobacillus ferrooxidans</i> and associated iron and sulfur oxidizing consortia) is retained from the residue; the process engineering component encompasses harvesting, concentration, formulation (e.g., cryoprotection or encapsulation), and reactivation protocols to transform site adapted natural consortia into stable, commercial scale inoculum. Hence, the authors propose future research recommendations integrating microbial ecology, process engineering, pilot validation, and techno-economic analysis to transform closure from a costly endpoint into the foundation of a circular bioeconomy (an economic system that minimizes waste by reusing, recovering, and regenerating biological resources).</p> Graphical Abstract <p></p>

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Developments in Closure Strategies for Gold Heap Leach Facilities with Future Recommendations for Residue Valorization: A Review

  • 期刊论文

  • 发表日期：

    2026年7月3日

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  • Peng Hongge,
  • Deogratias Laurent Shauri,
  • Zhao Ting,
  • Gao Xiaodong,
  • Yin Jun

摘要

Gold heap leaching, responsible for nearly a third of global gold production, generates more than 500 million tonnes of spent ore residue annually, resulting in multibillion dollar closure liabilities and persistent environmental risks. This article reviews the evolution of closure strategies over the past six decades, ranging from rinsing and capping to advanced store and release covers and predictive simulation models, with objectives such as contaminant control, cost reduction, and environmental protection. A systematic synthesis of the published literature confirms existing approaches remain dominated by a containment paradigm (defined as an approach that isolates waste from the environment using physical and chemical barriers without recovering embedded value) that treats residues as liabilities, offering only incremental improvements through bioremediation and geochemical stabilization. Hardly any closure methodology reframes residues as resources, despite their biological activity and enrichment with extremophilic consortia such as Acidithiobacillus ferrooxidans. Therefore, a valorization pathway that systematically recovers and commercializes these microbes as high performance inoculum for refractory gold bioleaching would constitute a pioneering step in mine closure practice. The target microorganism (Acidithiobacillus ferrooxidans and associated iron and sulfur oxidizing consortia) is retained from the residue; the process engineering component encompasses harvesting, concentration, formulation (e.g., cryoprotection or encapsulation), and reactivation protocols to transform site adapted natural consortia into stable, commercial scale inoculum. Hence, the authors propose future research recommendations integrating microbial ecology, process engineering, pilot validation, and techno-economic analysis to transform closure from a costly endpoint into the foundation of a circular bioeconomy (an economic system that minimizes waste by reusing, recovering, and regenerating biological resources).

Graphical Abstract