Gold Cyanidation Plant Process Requirements

Gold cyanidation process refers to the method of extracting gold using cyanide as the leaching chemical. Due to the mature technology, high leaching rate and strong applicability to ore, cyanidation process is still one of the main methods for gold extraction.

In the gold cyanidation process, each step must be controlled to ensure good economic benefits.

01 Inflate and Add Cyanide

After grinding, cyanide is added to the pulp to dissolve gold and form a metal complex. The reaction formula is as follows.

4Au+8NaCN+O2+2HgO→4NaAu(CN)2+4NaOH

It can be seen from the above formula that oxygen is needed in the gold leaching process, so it is necessary to inflate the leaching tank in industrial production. The aeration pressure is generally about 1kg, and the aeration volume is more than 0.002m3 per cubic meter of slurry per minute.

02 Add Protective Alkali

In order to ensure the concentration of cyanide in the slurry, avoid environmental pollution, and prevent losses caused by the generation of toxic hydrogen cyanide (HCN) gas, alkali must be added to the leaching tank to keep the slurry at a higher pH value (10.5~11) . In industrial production, lime or lime milk is often used, and NaOH is sometimes added for supplementary adjustment.

03 Keep Slurry in Suspension

The gold cyanidation process has certain requirements on the performance of the leaching (adsorption) agitation tank. Under the condition of small power consumption, the particles with monomer separation or exposed surface gold in the pulp cannot be deposited in the tank, and the pulp, cyanide, lime and air should be fully mixed in the tank to reach the suspension state. The concentration of the slurry in each part of the tank should be consistent, and there should be no stratification along the depth of the tank, and the particle size distribution should be uniform.

04 Keep Slurry Concentration Appropriate

When the density of gold ore is 2.65~2.8. the general leaching slurry concentration is 40~45%. When the density of the flotation concentrate is 3~3.5. the general leaching concentration is 30~40%. Generally, materials with a fineness of less than 200 mesh account for 80-95%. Production practice shows that different materials and different production conditions also have different requirements for agitation tank.

05 Reduce the moving parts wear and noise

In order to reduce the wear of the agitator and increase the service life, most of the impellers in industrial production should be lined with rubber. The processing of the transmission device should be fine to ensure that the transmission efficiency is high and the noise is low.

06 Reduce Carbon Wear

In the carbon in pulp method, carbon is added to the adsorption tank to absorb gold. If the stirring power of the leaching tank is too strong, the carbon will grind and lose. And if the stirring force is weak, deposits will occur. Therefore, while maintaining the pulp in suspension state, on the one hand, it is required to choose the carbon with high hardness for production, and on the other hand, it is necessary to reduce the rotating speed of the impeller to reduce the loss of carbon and the input power of the agitation adsorption tank.

07 Determine Appropriate Capacity

At present, the common gold cyanidation plant processing capacity ranges from dozens of tons to tens of thousands of tons per day. The larger the capacity, the larger the plant area, the larger the equipment specifications and investment. Each mine owner must determine the appropriate capacity of the processing plant according to the actual situation.

08 Reduce Equipment Weight and Investment

When choosing leaching tank, on the one hand, the leaching process should be high efficiency and energy saving, while the transmission device is required to occupy a small area and light weight. When the capacity, pulp concentration and leaching time are determined, the number of leaching tanks can be determined. However, the specifications of the leaching tank should be adapted to plant capacity. When building a 500t/d gold cyandation plant, it will increase the required equipment and increase the investment when using φ3.5X3.5m leaching tank. Therefore, only the equipment is light and the capacity is suitable can reduce the enterprise construction investment.

09To Wrap Up

The above are the eight process requirements of the gold cyanidation plants. Each mine owner must strictly control each production step in actual production and monitor various parameters to prevent economic losses due to improper operation. The mine owners can also consult with the manufacturers with the overall qualification of the beneficiation plant. It is important to carry out the beneficiation test in advance and determine the appropriate beneficiation plan through the test results.