What Are the Common Methods of Gold Leaching?

Gold leaching is one of the important processes for gold extraction. Different leaching methods can be used according to different types of gold ores to improve the recovery rate and grade of gold. For example, for natural gold ore, gravity separation, flotation and other methods can be used for separation; for sulfide gold ore, it is necessary to first undergo oxidation treatment, and then use cyanide leaching and other methods to extract gold; for oxidized gold ore, cyanide leaching and other methods can be used directly to extract gold.

The process of gold leaching usually requires multiple links such as crushing, grinding, grading, stirring, leaching, solid-liquid separation, etc., and the process is relatively complicated. At the same time, in order to improve the recovery rate and grade of gold, various agents such as oxidants, inhibitors, activators, etc. need to be added, which further increases the complexity of the process.

Let's take a look at what methods are there for leaching gold? Currently, the most common methods are cyanide leaching, thiourea leaching, chlorination leaching and biological leaching.

01Cyanidation process of gold leaching

Cyanidation process of gold leaching is to extract gold from ore by using the solubility of gold in cyanide solution. In the presence of oxygen, gold reacts with cyanide to form a gold-cyanide complex, which dissolves gold in the solution.

The recovery rate of gold in cyanide leaching is relatively high, and the process is mature and the operation is simple. However, cyanide leaching also has some disadvantages, such as cyanide is toxic, has a great impact on the environment, and has limited adaptability to ores.

Generally, cyanide leaching is more suitable for oxidized gold ores, some sulfide gold ores, natural gold ores, and gold ores containing a large amount of impurities such as copper, lead, and zinc. However, pretreatment is required before leaching to remove impurities before cyanide leaching.

02Thiourea Gold Leaching Process

Thiourea gold leaching is to extract gold from ore by utilizing the solubility of gold in thiourea solution. Under acidic conditions, gold reacts with thiourea to form a gold-thiourea complex, thereby dissolving gold in the solution. Thiourea leaching of gold is characterized by being non-toxic, environmentally friendly, and highly adaptable to ores. However, the recovery rate of thiourea leaching of gold is relatively low, the cost of reagents is high, and the process is relatively complicated.

Usually, thiourea leaching is more suitable for oxidized gold ores, partially sulfided gold ores, and ores containing a large amount of impurities such as copper, lead, and zinc. For natural gold ores, thiourea leaching is not as effective as cyanide leaching.

03Chlorination gold leaching process

Chlorination leaching of gold is to extract gold from ore by using the solubility of gold in chloride solution. Under acidic conditions, gold reacts with chloride ions to form gold-chloride complexes, thereby dissolving gold in the solution. Chlorination leaching of gold has a high recovery rate, strong adaptability to ores, and low reagent cost. However, when leaching gold by chlorination, the chloride used is toxic, severely corrosive to equipment, and has a great impact on the environment.

The leaching effect is better for oxidized gold ores and some gold ores containing a large amount of impurities such as copper, lead, and zinc.

04Bioleaching of gold mines

Bioleaching gold is the process of extracting gold from ores by using the metabolism of microorganisms. Microorganisms can oxidize sulfides in ores into sulfates, while releasing gold and dissolving it in the solution. Bioleaching gold is characterized by being non-toxic and environmentally friendly. However, the leaching cycle is long, the gold recovery rate is relatively low, and the adaptability to ores is limited.

The above is an introduction to the gold leaching method, but the industry for leaching gold will be different for different types of gold ore. Therefore, when choosing a gold leaching method, it is necessary to comprehensively consider factors such as the type of ore, the occurrence state of gold, environmental requirements, and cost, and select the most suitable leaching method to improve the gold recovery rate and grade while reducing the impact on the environment.