Gold extraction process from cyanide solution

Cyanide extraction is one of the mainstream methods for extracting gold from ore, with efficient and mature technical means. The following are several main processes for extracting gold from cyanide solution:

1. Cyanide leaching process

The cyanide leaching process is the process of reacting the gold in the gold-bearing ore with cyanide to form a complex and enter the solution. The specific steps include:

Ore preparation: crushing and grinding the ore to reduce the particle size of the ore and improve the gold recovery rate.

Leaching: transport the ground ore to the leaching tank, stir the slurry by mechanical force or injecting air to increase the contact between cyanide and gold and improve the leaching efficiency. The cyanide concentration ranges from 300 to 500 mg/L (0.03 to 0.05% in terms of NaCN), which mainly depends on the mineralogical properties of the ore.

Washing: In order to recover the gold-bearing solution after leaching, the dissolved gold on the surface of the ore particles and between the ore particles is washed with water to achieve solid-liquid separation.

2. Zinc exchange method

The zinc exchange method is a traditional method for extracting gold from cyanide solution. The specific steps include:

Leaching: dissolving the gold in the ore in an oxygen-containing cyanide solution.

Washing: reducing the concentration of gold ions in the gold-containing solution after leaching.

Exchange: using metallic zinc to reduce and precipitate gold from the gold-containing solution and recover gold.

3. Carbon-in-Pulp Method (CIL and CIP)

The carbon-in-pulp method is a widely used method in modern gold extraction technology, including the full-mud cyanide carbon-in-pulp method (CIL) and the unfiltered cyanide carbon-in-pulp method (CIP). The specific steps include:

Screening: using a 0.6mm sieving machine to pre-screen the ore pulp.

Adsorption: using activated carbon to adsorb the dissolved gold.

Separation: using a 0.85mm sieving machine to separate the gold-loaded carbon.

Desorption: desorbing gold from the gold-loaded carbon.

Recovery: using electrolysis to recover gold from the desorbed gold-containing precious solution, and the desorbed carbon can be regenerated to remove impurities.

4. Heap leaching gold extraction process

The heap leaching gold extraction process has the advantages of short production process, easy to master technology, low investment, and quick results. It is particularly suitable for treating low-grade impregnation-type deposits. The specific steps include:

Ore preparation: crush the raw ore and then heap leaching.

Leaching: leaching the gold in the ore through cyanide solution.

Recovery: collecting the gold in the leaching solution.

5. Flotation concentrate cyanidation gold extraction process

The flotation concentrate cyanidation gold extraction process is generally used to treat gold-containing sulfide primary ores, ores with low mud content, easy flotation enrichment, and high recovery rate. The specific steps include:

Floatation: flotation enrichment of ore to increase the gold grade of the concentrate.

Cyanidation: mix the flotation concentrate with cyanide solution and perform cyanidation leaching.

Recovery: recover gold through methods such as zinc replacement or activated carbon adsorption.

6. Resin gold extraction process

The resin gold extraction process is a method of using ion exchange resin to adsorb gold from cyanide solution or cyanide ore slurry. The specific steps include:

Adsorption: After mixing the ore pulp with the cyanide solution, the gold is dissolved into gold cyanide, and ion exchange resin is added to adsorb the gold.

Desorption: Desorb the gold from the resin.

Recovery: Recover gold from the desorbed gold-containing precious liquid by electrolysis