The tailings are the main component of industrial solid waste, which has a low content of useful components and cannot be economically used in industrial production at present. With the continuous exploitation of gold mine resources and the progress of refractory gold processing technology, the emission of gold tailings increases year by year, which inevitably brings a series of problems and further stimulates the development of gold tailings disposal methods and comprehensive utilization of gold tailings.
In addition to the increasing amount of gold tailings, the gold processing usually adopts the cyanidation leaching process or flotation process to extract the gold, in which the cyanide and flotation reagents must be added in the above gold processing technology, resulting in a certain amount of cyanide and flotation reagents remaining in the gold tailings. Therefore, the following problems often exist in the discharge of gold tailings:
1. Occupy a large number of land because of the long-term accumulation.
2. Pollute the environment. The chemical agents must be added in the gold processing, and these residues will be left in the tailings, and the heavy metals, toxic and harmful pollutants contained in the gold tailings will cause harm to the surrounding environment. If they flow into the downstream or infiltrate into the underground, even the very fine sand particles of the tailings carried by the wind.
3. Waste of resources. Restricted by the previous mineral processing technology, a large number of valuable resources are still left in the tailings and have not been comprehensively utilized.
4. Safety hazards. Tailings pond has safety hidden danger, such as collapse, slide.
Based on the above problems, the gold tailings disposal methods and comprehensive utilization of gold tailings is extremely urgent. At present, the common gold tailings disposal methods and comprehensive utilization mainly include the following ways:
The gold content in the gold tailings is generally 0.2-0.6g/t. Due to the backward mining and processing technology in the past, a part of gold and silver was lost in the tailings. Meanwhile, most of the gold ores in China are associated with copper, lead, zinc, iron, sulfur and other elements. With the progress of gold processing technology, some valuable elements can also be recovered comprehensively according to the nature of the tailings in gold tailings reprocessing. Therefore, the gold tailings reprocessing method has become one of the major trends in gold tailings disposal methods.
Taking the recovery of lead-zinc ore from gold tailings as an example, the lead-zinc ore in gold concentrate underwent the fine grinding and long-time aeration stirring during the cyanide leaching process, which resulted in serious overgrinding and colloid-like dispersion system, resulting in the difficulty of flotation. In addition, a large number of argillaceous minerals and residual cyanide formed the hydrophilic film on the mineral surface, which made the collector lose its selectivity for various minerals. Meanwhile, the film also hindered the adsorption between the collector and the mineral surface, increasing the difficulty of flotation separation.
◆ Adopt the pretreatment to achieve the ultra-fine flotation. That is, adopt the combined collector, pulp potential and pH control measures.
◆ Adopt the strong oxidation of concentrated sulfuric acid and adsorption of activated carbon, and adopt the mixed flotation process under acidic medium to achieve the comprehensive utilization ratio of lead-zinc mineral resources in cyanidation tailings.
As one of the most important gold tailings disposal methods, the tailings dry stacking process alleviates the storage pressure of tailings pond, reduces the safety hidden danger of tailings pond, and the use of backwater reduces the pressure of sewage treatment, saves the production and operation cost of mine, which is the requirement of national green and environmental protection for mine construction.
For the gold ore tailings extracted with the cyanidation leaching process, the filter press can be used to filter the tailings. As the filtrate is returned to the process, the cyanide ions, alkali and most of the dissolved gold in the filtrate are recovered, thus saving the amount of mineral processing water, lime and cyanide, and reducing the cyanide wastewater discharge.
The recovery of valuable elements from gold tailings can only realize the comprehensive recovery of a small number of valuable elements in tailings, but it cannot significantly reduce the number of tailings, and still cannot fundamentally solve the problems, such as occupying a large amount of land, destroying and affecting the ecological environment.
Taking the gold deposits in China as an example, the types of deposits and surrounding rocks are complex, the content of metallic minerals in some deposits is rare, and the gangue minerals are relatively pure. The gold tailings can be directly used as an important raw material of non-metallic or building material, such as brick-making, glass-ceramics preparation, aerated concrete production, Portland cement.
Using the tailings to fill the mine goaf is one of the effective ways to directly use the gold tailings, especially for those mining enterprises that have no place to set up gold tailings pond, using tailings to backfill mine goaf has the greater environmental and economic significance.
As a kind of better filling material, the tailings can be used locally and waste can be utilized, and the cost of collecting, crushing, transportation and other production of filling gravel can be exempted. For the gold ore bodies of high value, the tailings can improve the mining conditions of ore pillars and reduce the dilution loss. The cement or other cementing materials are often added into the filling materials to make the loose tailings solidify into a whole with certain strength.
Reclamation is also one of the effective gold tailings disposal methods. Certain measures should be taken in the gold mine tailings pond. Planting the agricultural, forestry and animal husbandry crops with strong vitality can protect the soil and fix the dike, which will play a positive role in protecting the environment and preventing pollution.
The above are the common gold tailings disposal methods and comprehensive utilization methods. In the practical application of concentrator, it is suggested to determine the suitable gold tailings disposal methods and comprehensive utilization method by the tailing's nature, scale and return on investment of gold tailings, etc., and to customize the reasonable gold tailings disposal equipment.
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