Gold, as one of the oldest and most important precious metals in the world, has been highly sought after since ancient times. However, gold does not exist in nature in the form of pure gold but is found in the form of ores in various corners of the Earth. Therefore, extracting pure gold from gold ore is a complex process involving both technology and engineering. This article will explore the refining process of gold ore, including several common methods and processes for extracting gold from gold ore.
Gold ore refers to rocks or ores containing gold minerals, and there are many types, including:
1. Gold in quartz veins: Gold often coexists with quartz veins or vein-type ore bodies, occurring in vein-like, sheet-like, or granular forms. (Quartz vein-type gold ore dressing method)
2. Sulfide-type gold ore: Gold contained in sulfides such as pyrite, chalcopyrite, and chalcocite, commonly found in sulfide metal deposits.
3. Oxide-type gold ore: Gold in free form contained in oxides such as hematite, manganese ore, commonly found in oxidized metal deposits.
4. Silicate-type gold ore: Gold contained in silicate rocks such as pyrite and chalcopyrite, commonly found in metamorphic or sedimentary rocks.
The methods of extracting gold mainly include physical methods and chemical methods, which will be described separately:
Physical Methods
a. Gravity Separation: Separation based on the density difference between gold and other minerals. Commonly used equipment includes shaking tables, spiral concentrators, and centrifugal separators.
b. Dense Media Separation: Separation based on the density difference of media. Common media include water, heavy media, etc.
c. Magnetic Separation: Separation based on the magnetic difference between gold and other minerals. Commonly used equipment includes magnetic separators and high-gradient magnetic separators.
Chemical Methods
a. Cyanide Leaching: Immersing gold ore in a cyanide-containing leaching solution to form a complex with cyanide, and then extracting gold by electrolysis or adsorption.
b. Chloride Leaching: Immersing gold ore in a chloride-containing leaching solution to dissolve gold into chloroauric acid, and then extracting gold by reduction or electrolysis.
c. Oxidation Leaching: Immersing gold ore in an oxidation reagent-containing leaching solution to oxidize gold into a soluble compound, and then extracting gold by reduction or electrolysis.
The gold refining process varies depending on the characteristics of the gold ore and the extraction methods used. Generally, the gold refining process includes the following steps:
1. Crushing and Grinding of Ore: Preliminary crushing and grinding of raw gold ore to achieve a particle size suitable for subsequent flotation or leaching operations.
2. Ore Dressing or Leaching: Selecting the appropriate extraction method based on the characteristics of the ore and conducting ore dressing or leaching operations to extract gold from the ore.
3. Flotation or Concentration: Further processing of gold concentrate obtained during ore dressing to increase the gold content.
4. Refining or Purification: Refining or purifying the gold concentrate to obtain high-purity metallic gold.
5. Electrolysis or Adsorption: Extracting gold from the refined gold concentrate using electrolysis or adsorption to obtain pure gold products.
6. Tailings Treatment: Processing the tailings generated during the extraction process to recover useful metals or reduce environmental pollution.
In summary, extracting and refining gold is a complex process that requires a combination of ore characteristics and extraction method selection. Through multiple steps of operation and processing, high-purity metallic gold can be obtained. In actual production, various technical means should be flexibly applied according to the ore conditions and process requirements to ensure the effective extraction and utilization of gold.
