A systematic review of gold extraction: Fundamentals, advancements, and challenges toward alternative lixiviants

Since the birth of cyanidation, it has been dominant in the gold extraction industry. Recently, with the increasing awareness of environmental hazards and potential risks posed by the severe toxicity of cyanide, attempts to seek alternative lixiviants have arisen. Over the past three decades, a significant amount of literature has examined alternative lixiviants to cyanide for recovering gold, while few industrial applications have been reported due to various obstacles, such as toxicity, excessive consumption, or low leaching efficiency. These obstacles are pro-gressively overcome in multiple ways, including process improvement, system optimization, use of co -intensifying systems, and development of additives. In this paper, related studies about alternative lixiviants and methods such as cyanide, thiosulfate, thiourea, thiocyanate, polysulfides, halides, and microbial leaching are summarized. The history, fundamentals, advancements, and challenges of alternative lixiviants are fully concluded to provide a reference for cleaner gold production. In addition, the comprehensive performance of lixiviants was evaluated according to a novel evaluation criterion proposed in terms of economy, efficiency, and environment.

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This paper summarizes the research on alternative lixiviants and methods for gold extraction, including cyanide, thiosulfate, thiourea, thiocyanate, polysulfides, halides, and microbial leaching. Various obstacles, such as toxicity, excessive consumption, and low leaching efficiency, have been progressively overcome through process improvement, system optimization, the use of co-intensifying systems, and the development of additives. The comprehensive performance of lixiviants is evaluated based on economy, efficiency, and environment.