How Does Gold Heap Leaching (Cyanide) Work for Low-Grade Ores?

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The gold heap leaching process, a widely – used method in the gold extraction industry, has its own unique characteristics and application scenarios. This process, especially the cyanide heap leaching approach, which uses cyanide as the leaching agent, is a key technology for processing certain types of gold ores.
The gold heap leaching process, specifically cyanide heap leaching, is generally only suitable for the treatment of low – grade gold ores, particularly low – grade oxidized ores. Most of these oxidized ores are surface – oxidized ores. Given the coarse ore particle size in the gold heap leaching process, the interaction between the ore and the cyanide leaching agent is relatively weak. As a result, the gold leaching rate is not as high as some other leaching methods, which restricts its application mainly to low – grade ores.
Based on a large number of industrial practices, among the oxidized ores suitable for the gold heap leaching process (cyanide heap leaching), gold exists in various ore types. These include gold – bearing quartz vein, gold – bearing breccia, structural altered rock, andesite, sandstone, porphyry, hydrothermal metamorphic rock, silicified mylonite, secondary gold – bearing gossan, and so on. Gold that exists in gangue or mineral fissures, as well as gold with small particles and easy to be exposed, is quite suitable for the cyanide heap leaching within the gold heap leaching process.

堆浸水印 - How Does Gold Heap Leaching (Cyanide) Work for Low-Grade Ores?

The gold ores suitable for the cyanide heap leaching mainly fall into the following three types:
① Disseminated oxidized ore;
② Sulfide ore in which gold does not coexist closely with sulfide minerals;
③ Vein gold deposit or placer gold deposit with small gold particles or large specific surface area of gold particles.

gold heap leaching process - How Does Gold Heap Leaching (Cyanide) Work for Low-Grade Ores?

The ore suitable for the gold heap leaching process gold extraction should possess the following characteristics:
① The gold grade is low, mostly in the range of 1.0 ~ 3.0g/t, and only the gold ore grade of individual deposits is greater than 3.0g/t. This low – grade nature makes the gold heap leaching process, especially cyanide heap leaching, an economically viable option as it can still extract gold from ores that might not be profitable to process with other more expensive methods.
② The embedded particle size of gold is fine or flat, which makes it easy to be leached by cyanide in the cyanide heap leaching process within the overall gold heap leaching process. Fine – grained or flat – shaped gold particles can have better contact with the cyanide leaching agent, facilitating the dissolution of gold.
③ The ore is loose, porous, and permeable due to oxidation and weathering. These physical properties are beneficial for the cyanide solution to penetrate the ore heap in the cyanide heap leaching process, ensuring that the leaching agent can reach the gold – bearing minerals effectively during the gold heap leaching process.
④ For the ore with few pores, the gold can be exposed by crushing method. This preparation step is crucial before the cyanide heap leaching within the gold heap leaching process, as it enables better access of the cyanide leaching agent to the gold.
⑤ The ore contains no or less acidic substances and no or less elements that can react with cyanide. This is essential because acidic substances or reactive elements can consume the cyanide leaching agent, reducing the efficiency of the cyanide heap leaching process in the gold heap leaching process.
⑥ The ore does not contain substances that adsorb or precipitate dissolved gold. If such substances are present, they can hinder the extraction of gold during the cyanide heap leaching process within the gold heap leaching process, reducing the overall gold recovery rate.

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