Cyanidation Process for Gold Extraction-Efficient Gold Recovery Method

In the gold beneficiation process, cyanidation process of gold extraction plays an important role. This method is widely used in gold beneficiation plants due to its high gold recovery capacity and low cost. With the increase of global environmental awareness, cyanidation process of gold extraction technology is facing new challenges and opportunities. In the following article, we will introduce you to the principle, process flow and influencing factors of cyanidation gold extraction, providing valuable reference for the mineral processing industry.

01Principle and process of gold extraction by cyanidation process

Basic principle

The core of gold extraction by cyanidation lies in the chemical reaction between gold, cyanide and oxygen. In this reaction, gold dissolves under the action of cyanide and oxygen to form a soluble gold-cyanide complex, thereby separating gold from ore and creating conditions for subsequent gold recovery.

Detailed explanation of the process flow

1. Crushing and grinding: After mining, gold ore needs to be crushed and ground to fully expose the gold particles. This process can improve the leaching efficiency of gold ore. Common gold ore crushing equipment includes jaw crushers and cone crushers, which can crush the ore to a suitable particle size. Subsequently, a ball mill can be used to further refine the ore particle size, providing favorable conditions for the dissolution of gold particles.

2. Cyanide leaching: After crushing and grinding, the gold ore enters the cyanide leaching stage. The stirring leaching method or heap leaching method is selected according to the ore grade and properties of the gold ore. In general, the stirring leaching method is suitable for the treatment of high-grade gold ore. The stirring equipment can make the slurry and the cyanide solution fully contact, and the gold dissolution process is completed in a shorter time. The heap leaching method is suitable for the treatment of low-grade ore. The ore is piled on a special site and sprayed with cyanide solution. These solutions penetrate the ore pile and dissolve the gold particles. This method has a long cycle, but the cost is low, and it can be used in large-scale production beneficiation plants.

3. Gold recovery: Since the leaching solution contains gold-cyanide complexes, specific methods are required to recover gold. Common methods include carbon-in-pulp process (CIP), carbon-in-leach process (CIL) and zinc powder replacement process. The CIP and CIL processes use activated carbon to adsorb gold-cyanide complexes, and then obtain gold through desorption and electrolysis. The zinc powder replacement method is used to treat ores with high silver content.

02Factors affecting gold extraction by cyanidation process

1. Influence of ore properties

(1) Influence of sulfide ores: This type of ore will increase the amount of oxygen and cyanide, thereby affecting the dissolution efficiency of gold. When the ore contains pyrite, a side reaction will occur during the cyanidation process, and the pyrite will be oxidized into sulfate and iron cyanide. This reaction process will consume a large amount of oxygen and cyanide, change the chemical environment of the solution, and reduce the dissolution efficiency of gold. Therefore, for ores containing sulfide minerals, pre-oxidation treatment methods such as roasting and bacterial oxidation are required to reduce their impact on the cyanidation gold extraction process.

(2) Influence of carbonaceous minerals: Because carbonaceous minerals are adsorbent, they may adsorb gold-cyanide complexes, resulting in gold loss. To address this problem, roasting or adding inhibitors can be used to reduce the adsorption of gold-cyanide complexes by carbonaceous minerals and improve the gold recovery rate.

2. Influence of cyanidation parameters

(1) Cyanide concentration: The cyanide concentration in the cyanidation gold extraction process generally needs to be controlled between 0.01% and 0.05%. Too low a concentration will reduce the dissolution rate of gold and prolong the leaching time. Too high a concentration will accelerate the dissolution rate of gold, but at the same time the consumption of cyanide will also increase, thereby increasing production costs and the risk of environmental pollution.

(2) Solution pH: The pH value in the cyanidation gold extraction process needs to be maintained between 10 and 11. This pH value of the solution can effectively prevent the volatilization of hydrogen. Because under acidic conditions, hydrogen cyanide is easy to volatilize, which will not only cause the loss of cyanide, but also pose a threat to the safety of workers. Under alkaline conditions, hydride is relatively stable, which is conducive to the dissolution reaction.

(3) Oxygen supply: Adequate oxygen can accelerate the dissolution rate of gold. In the cyanidation leaching process, the oxygen content in the solution can be increased by increasing the ventilation volume, stirring intensity or adding oxidants to accelerate the leaching efficiency of gold.

The above is a brief introduction to gold extraction by cyanidation process. With its high efficiency and mature process, cyanidation has become the mainstream technology in the gold mining industry. However, attention should be paid to its environmental and safety issues, and the risk of environmental pollution should be reduced by continuously optimizing the process and improving environmental protection technology. Xinhai Mining can customize the design of gold mine cyanidation process according to the mineral processing test results of the customer's ore, ensure the high leaching efficiency and recovery rate of the gold mine, and improve the economic benefits of the mineral processing plant.