Heap leaching process for gold extraction, due to the coarse ore particle size, weak interaction with cyanide leaching agent and relatively low gold leaching rate, is generally only suitable for the treatment of low-grade gold ores, especially low-grade oxidized ores, most of which belong to surface oxidized ores.
According to a large number of industrial practices, among the oxidized ores available for heap leaching, gold has different ore types, including 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 existing in gangue or mineral fissures and gold with small particles and easy to be exposed are easy to heap leaching.
The gold ores suitable for heap leaching mainly belong to 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.
The ore suitable for heap leaching process gold extraction should have 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;
② The embedded particle size of gold is fine or flat, which is easy to cyanide leaching;
③ The ore is loose, porous and permeable due to oxidation and weathering;
④ The gold in the ore with few pores can be exposed by crushing method;
⑤ The ore contains no or less acidic substances and no or less elements that can react with cyanide;
⑥ The ore does not contain substances that adsorb or precipitate dissolved gold.