Gold Tailings Characteristics & Extraction Methods

Gold tailings are a byproduct of the mining process, usually referring to the metal and mineral residues that have not been extracted during the extraction of gold ore (such as flotation, cyanidation, gravity separation, etc.). These tailings are often regarded as waste, but in fact, they may contain metal resources that have not yet been extracted especially gold. Researching and developing new tailings extraction technologies to turn waste into treasure has important economic and environmental significance. Next, we will introduce the characteristics and extraction methods of gold tailings to promote the sustainable development of gold tailings and make gold tailings recycling more green, intelligent, and resource-based.

 

 

Characteristics of Gold Tailings

The main sources of gold tailings include waste rock, low-grade ore, grinding products, and slag after beneficiation. The following is a detailed analysis of the characteristics of gold tailings from the aspects of composition, hazards, and comprehensive utilization.

 

1. Composition characteristics of gold tailings

• Chemical composition
  Gold tailings are mainly composed of silicon aluminum oxides, with the main components being SiO₂ (usually accounting for more than 50%), CaO, Al₂O₃, Fe₂O₃, and a small amount of MgO, which are similar to the composition of building materials. In addition, they also contain trace amounts of valuable metal elements such as gold, silver, copper, lead, zinc, and residual beneficiation agents (such as cyanide).
• Mineral composition
  It mainly includes non-metallic minerals such as quartz, feldspar, mica, clay, and incompletely separated metal sulfides (such as pyrite) and oxides. Due to the limitations of early beneficiation technology, some tailings still contain unrecovered encapsulated gold or fine gold particles.
• Physical properties
  Tailings particles are small (mostly micrometers), easily diffused with water or wind, and long-term accumulation may generate acidic wastewater due to oxidation reactions, leading to the release of heavy metal ions (such as lead and arsenic).

 

 

2. Hazards of gold tailings

Environmental issues

• Land occupation: Tailings ponds occupy a large amount of land resources. The annual increase in global gold tailings is about 24.5 million tons, and the cumulative stockpile in my country has exceeded 200 million tons.
• Pollution risk: Heavy metals and acidic wastewater in tailings may pollute groundwater and soil through leakage, and flying dust will also affect air quality.
• Safety hazards: Tailings dam collapse or landslides may cause secondary disasters such as mudslides.

Resource waste

If the valuable metals and non-metallic minerals (such as quartz and feldspar) remaining in gold tailings are not recovered, it will cause resource waste. For example, the gold grade of some tailings can still reach 0.2-1.5 grams/ton, and resources worth tens of billions of yuan can be recovered through reselection.

 

3. Comprehensive Utilization of Gold Tailings

Recovery of Valuable Metals

• Reselection Technology: Use flotation, cyanide leaching, bioleaching, and other methods to extract residual gold, silver, and other precious metals. For example, through new environmentally friendly gold leaching agents or acid leaching pretreatment, the gold recovery rate can reach 70%-80%.
• Combined Process: Combine magnetic separation, gravity separation, and other technologies to recover associated metals such as iron and copper, such as spiral chutes and centrifuges for the separation of coarse gold.

Utilization of Non-metallic Resources

• Building Materials: Tailings can replace sand and gravel to prepare concrete, sintered bricks (mixing amount 20%-100%), ceramsite (mixing amount 50%-90%), etc., reducing dependence on natural resources.
• High value-added products: Use silicon and aluminum components to produce ceramics, glass, microcrystalline glass, etc. Some tailings can also be used as soil conditioners or cementitious materials for filling goaves.

Environmental protection disposal

• Underground filling: Mix tailings with cementing materials and backfill the goaf to reduce the risk of surface collapse and reduce the amount of tailings stockpiles.
• Harmless treatment: Fix heavy metals through chemical precipitation, microbial solidification, and other technologies to reduce environmental pollution.

 

 

Gold Tailings Extraction Methods

The gold and other valuable metals remaining in gold tailings can be recovered through a variety of technical means, combining traditional processes with innovative technologies. The following are the current mainstream and cutting-edge extraction methods.

 

Gravity Separation

Gravity separation is a traditional tailings treatment method that uses the density difference between metals and other substances in the tailings for separation. However, with the development of technology, modern gravity separation has gradually introduced more sophisticated equipment and technology. For example, the use of efficient shaking tables and spiral separators can better separate gold particles from tailings. This method is suitable for gold tailings with large particle sizes and obvious density differences, and it is simple to operate and low in cost.

 

Flotation

Flotation is also a common method for extracting gold minerals from gold tailings. In recent years, researchers have improved flotation reagents and developed some new selective flotation reagents. These reagents can more effectively separate gold minerals from other minerals and improve the recovery rate of gold. Flotation is particularly suitable for gold tailings with small particle sizes and good dispersion and can reduce the environmental pollution of tailings to a certain extent.

 

Bioleaching

In recent years, bioleaching has also gradually attracted attention. This method uses the metabolism of certain microorganisms to dissolve metal ions from tailings. The advantages of bioleaching are its environmental friendliness and economy. By biologically treating tailings, not only can gold be effectively extracted, but also the impact of tailings on the environment can be reduced. This method is particularly suitable for the treatment of low-grade gold tailings and can achieve resource recovery without incurring additional costs.

 

In terms of scenario application, mining companies can flexibly choose the above methods in combination with different gold tailings characteristics. For example, for gold tailings with large density differences, gravity separation can be the first choice; for tailings with smaller particle sizes, flotation or bioleaching can be used. In actual operation, multiple methods can also be combined to form a comprehensive treatment plan to improve the recovery rate and economic benefits of gold.

With the advancement of science and technology, the application of automation and intelligent technology in gold tailings extraction is also increasing. Through sensors and data analysis technology, the gold content in tailings can be monitored in real-time, so as to adjust the extraction process and optimize resource utilization efficiency. This intelligent treatment method not only improves production efficiency but also reduces labor costs.

In terms of environmental protection, new technologies for extracting gold tailings are also constantly developing. By adopting a closed-loop circulation system, the pollution of tailings to the surrounding environment can be reduced. With the deepening of research on tailings reuse, more and more mining companies have begun to explore the possibility of converting tailings into building materials or other products, thereby achieving a win-win situation of economic benefits and environmental protection.

The extraction technology of gold tailings is constantly improving. The combination of traditional methods such as gravity separation, flotation, and bioleaching with new technologies provides a variety of options for the efficient recovery of gold tailings. Through reasonable process design and intelligent management, mining companies can not only effectively improve resource recovery rates, but also make positive contributions to environmental protection. In the future, with the further development of science and technology, the resource utilization of gold tailings will usher in a broader prospect.