Five Methods for Gold Mine Tailings Treatment and Comprehensive Recovery

Tailings, generated during mineral processing operations, are low in useful components and currently uneconomical for industrial production. They are also a major component of industrial solid waste. With the continued exploitation of gold mine resources and advancements in beneficiation technology for refractory gold ores, the volume of gold mine tailings discharged has increased annually, inevitably leading to a series of problems and further stimulating the development of gold mine tailings treatment and comprehensive utilization. In addition to the increasing volume of gold mine tailings, gold mine beneficiation often utilizes cyanide extraction or flotation methods. These processes require the addition of cyanide and flotation reagents, resulting in a certain amount of cyanide and flotation reagents remaining in the gold mine tailings.

Therefore, the discharge of gold mine tailings often presents the following problems:

1. Long-term storage occupies a large amount of land.

2. Environmental Pollution: Chemical reagents must be added during the gold beneficiation process, and these residues remain in the tailings. Heavy metals and toxic pollutants contained in the tailings can flow downstream or seep into the ground. Even extremely fine tailings sand particles carried by wind can harm the surrounding environment.

3. Resource Waste: Limited by the current state of mineral processing technology, a large amount of valuable resources remain in the tailings, unutilized.

4. Safety Hazards: Tailings ponds pose safety hazards such as collapse and landslides. Given these issues, the treatment and comprehensive utilization of gold mine tailings are urgent.

Currently, the following are common methods for the treatment and comprehensive utilization of gold mine tailings:

I. Gold Tailings Reprocessing

The gold content in gold mine tailings is generally 0.2-0.6g/t. Due to outdated mining and beneficiation technologies in the past, some gold and silver were lost in tailings. Furthermore, most Chinese gold ores are associated with copper, lead, zinc, iron, and sulfur. With advances in beneficiation technology, gold tailings re-selection can recover not only gold and silver but also valuable elements based on the tailings' properties. Therefore, tailings re-selection has become a major trend in gold tailings treatment. Taking the recovery of lead and zinc from gold tailings as an example, the lead and zinc minerals in the gold concentrate undergo fine grinding and prolonged aeration and agitation during the cyanide leaching process, resulting in severe over-grinding and a "colloidal" dispersion, making flotation difficult. Furthermore, the presence of large amounts of argillaceous minerals and residual cyanide creates a hydrophilic film on the mineral surface, which reduces the collector's selectivity for various minerals. The film also hinders the collector's adsorption to the ore particle surface, complicating flotation separation. Ultrafine particle flotation can be achieved through pretreatment, the use of combined collectors, and control of the slurry potential and pH. 2. Slurry pretreatment technologies such as concentrated sulfuric acid oxidation and activated carbon adsorption can be employed, along with a mixed flotation process in an acidic medium to improve the comprehensive utilization of lead and zinc mineral resources in cyanide tailings.

II. Gold Mine Tailings Dry Discharge Process

The dewatered tailings dry discharge process alleviates tailings pond capacity pressure and reduces safety hazards. The reuse of return water reduces wastewater treatment pressure, saving mine production and operating costs, and is a national requirement for green and environmentally friendly mine development. Gold Mine Tailings Filter Press Dewatering: For gold tailings extracted using full-slime cyanide extraction, a filter press can be used. Since the filtrate is returned to the process, the cyanide ions, alkali, and dissolved gold in the filtrate are largely recovered, saving on beneficiation water, lime, and cyanide, while also reducing the discharge of cyanide-containing wastewater.

III. Production of Building Materials

Recovering valuable elements from tailings can only achieve comprehensive recovery of a small amount of valuable elements in the tailings, but it cannot significantly reduce the amount of tailings produced, nor can it fundamentally address the problem of tailings storage occupying large amounts of land, damaging the ecological environment, and impacting the environment. Taking my country's gold mines as an example, the deposit types are complex and the surrounding rock types are diverse. Some deposits contain rare metal minerals and relatively pure gangue minerals. Gold tailings can be directly used as important non-metallic raw materials or building materials, such as in brick making, glass-ceramics production, aerated concrete, and Portland cement production.

IV. Mine Backfill

Using tailings to fill mine goafs is an effective way to directly utilize gold tailings. This is especially true for mining companies without access to gold tailings ponds. Backfilling goafs with tailings offers greater environmental and economic benefits. Tailings are a highly effective filler material, allowing for local resource utilization and waste recycling, eliminating the costs of collecting, crushing, and transporting the gravel required to produce filler material. For high-value gold ore bodies, tailings can improve pillar recovery conditions and reduce dilution losses. An appropriate amount of cement or other binder is often added to the fill material to consolidate the loose tailings into a solid mass with a certain strength.

V. Land Reclamation

Land reclamation is also an effective method for gold tailings disposal. Taking appropriate measures within the gold tailings pond, such as planting agricultural, forestry, and animal husbandry crops, as well as resilient crops, can conserve soil and strengthen the embankment, contributing positively to environmental protection and pollution prevention.

The above are common methods for gold tailings treatment and comprehensive utilization. In actual application at a concentrator, it is recommended to comprehensively consider the nature of the gold tailings, the scale of the tailings, and the return on investment to determine the appropriate gold tailings treatment and comprehensive utilization method and tailor-make appropriate gold tailings treatment equipment.