Cyanide Leaching Gold Extraction Process

The cyanide leaching gold extraction process remains the most widely applied core gold extraction method globally due to its high maturity, superior gold recovery rates, and strong adaptability to various ores. The pre-treatment stage preceding cyanide leaching is critical. Its primary purpose is to oxidatively decompose the host minerals associated with gold in the ore, liberating and exposing encapsulated gold particles while removing harmful components that interfere with cyanide leaching. This lays the foundation for efficient subsequent leaching. Among various pre-treatment technologies, the oxidation roasting process is the most widely applied and technically mature, establishing itself as a fundamental processing technology for refractory gold ores.

The core principle of oxidation roasting relies on the action of air or oxygen to oxidize and decompose sulfide and arsenide minerals that encapsulate gold particles. This process breaks the mineral's grip on the gold, fully exposing it and thereby enhancing the efficiency of subsequent cyanide leaching. The process's greatest advantage lies in its adaptability, capable of treating diverse types of refractory gold ores. Its relatively simple operational procedures and low operating costs make it suitable for large-scale industrial production, leading to its widespread adoption globally in the pretreatment of refractory gold ores.

However, the oxidation roasting process also has significant limitations. It is highly sensitive to variations in operating parameters (such as temperature and airflow) and feed composition, making it prone to over-roasting or under-roasting during operation, which adversely affects gold leaching efficiency. In cases of under-roasting, insufficient decomposition of sulfide and arsenic minerals leaves portions of gold encapsulated, preventing participation in subsequent leaching. Conversely, over-roasting causes localized sintering of the roasted ore, sealing pores and re-encapsulating liberated gold (secondary encapsulation), directly reducing gold leaching rates. Under conventional production conditions, even after oxidation roasting pretreatment, cyanidation tailings still contain gold grades exceeding 5 g/t. However, gold leaching rates remain around 85%–90%, indicating potential for improvement.