The oxidized gold ore is gold-bearing ore that has undergone an oxidation process, the chemical process in which the ore is exposed to oxygen or other oxidizing agents. When gold-bearing ores oxidize, gold-bearing minerals and compounds chemically react with oxygen to form various oxidation products. The specific minerals and compounds present in the ore will determine the nature and composition of the oxidized material.
Common oxidized gold ores may contain minerals such as iron oxides (hematite, magnetite), iron hydroxides (goethite, limonite), and various clay minerals. These minerals are usually oxidized from iron-bearing sulfide minerals such as pyrite, which are common in gold-bearing deposits. When it comes to gold extraction, oxidized gold ores can present different challenges than unoxidized ores. The presence of oxidized minerals and compounds can affect the efficiency of gold in the beneficiation process, so specific techniques are required to efficiently recover gold. Depending on the degree of oxidation, different extraction methods such as cyanidation, flotation, or other chemical processes may be used. The following will introduce you to four oxidized gold ore extraction processes.
Use the table of contents below to navigate through the guide:
Traditional non-cyanidation methods include gravity separation, flotation separation and magnetic separation. These methods use the difference in physical properties between gold minerals and other non-gold minerals in the ore to achieve the separation and enrichment of gold.
1. Gravity separation: Gravity separation relies on the density difference between gold and other minerals for separation. The method uses gravity to separate the gold particles from the gangue minerals. Gravity separation can be performed using techniques such as centrifugal concentrators, shakers, and screw concentrators.
2. Flotation separation: Flotation separation is a widely used method for extracting gold from oxidized ores. It relies on the difference in surface properties between gold minerals and gangue minerals. During flotation process, collectors are added to create conditions that make the gold particles hydrophobic, allowing them to attach to the air bubbles and rise to the surface for recovery.
3. Magnetic separation: Magnetic separation uses the magnetic properties of minerals for separation. Although gold is generally not magnetic, some oxidized gold deposits may contain magnetic minerals associated with gold. These magnetic minerals can be separated from the ore using magnetic separation, leaving non-magnetic gold particles for further processing.
4. Amalgamation method: Amalgamation method is a traditional method that uses mercury and gold to form an amalgam. Gold-bearing ore is crushed and mixed with liquid mercury to form gold amalgam. The alloy is then heated, vaporizing the mercury and leaving behind the gold.
5. Heap leaching: Heap leaching is a commonly used technique for treating oxidized gold ores with lower gold grades. The ore is stacked in piles, and a leach solution containing chemicals such as sulfuric acid or an alkaline cyanide substitute is applied to the top of the pile. As the solution percolates through the heap, it leaches gold from it, which is subsequently recovered from the leachate.
Cyanidation is one of the most commonly used gold extraction methods and is especially suitable for treating oxidized gold ores. The process involves the use of a cyanide such as sodium cyanide or potassium cyanide to form a soluble gold cyanide complex with gold under alkaline conditions. Gold is then separated and recovered from the solution by methods such as adsorption, precipitation or electrolysis.
The cyanidation extraction method is widely used due to its high efficiency and ability to extract fine gold particles. However, it is important to note that cyanide is a toxic substance and strict safety measures and environmental controls must be implemented to ensure safe handling and disposal of cyanide solutions.
For oxidized gold ores, sulfide extraction methods can be used to convert oxidized gold minerals into sulfide minerals, which are generally more amenable to traditional sulfide treatment techniques. The sulfidation extraction methods used for oxidized gold ore include roasting method, high pressure oxidation method, biological oxidation method, chemical sulfidation method, etc. After sulfidation treatment of gold ore, gold can be extracted from the resulting sulfide minerals using conventional sulfidation treatments such as flotation or cyanidation.
For some oxidized gold ores, the oxidation roasting method can be used to extract gold. The method involves exposing the ore to oxygen at high temperatures, which oxidizes the gold into soluble compounds. Subsequently, the gold can be extracted from the oxidation products using leaching methods. Oxidative roasting extraction methods for oxidized gold ore mainly include: direct smelting method, chlorination roasting method, acid roasting method, high pressure oxidation method, etc. After oxidative roasting, gold can be recovered from the oxidation products using various extraction methods such as cyanidation, flotation or leaching.
The above are the four extraction methods of oxidized gold ore. The choice of these methods depends on factors such as the mineralogical characteristics of the ore, gold grade, available equipment and technology, and economic feasibility. In practical applications, multiple methods may be combined to treat oxidized gold ore to improve the gold recovery effect. The gold ore beneficiation method will change due to continuous technological development, so Xinhai Mining recommends choosing a professional beneficiation design manufacturer to carry out customized beneficiation scheme design to improve the beneficiation effect and economic benefits.