A large number of tailings are produced in the process of large quantities of gold mining. However, due to the early technology backwardness, part of the useful gold will be discharged with the tailings, and these gold still has recoverable value, through the reasonable process method for recycling, not only can improve the utilization rate of resources, but also can reduce environmental pollution. Generally speaking, the methods in gold tailings mainly include re-election, flotation and cyanide leaching.
1. Re-election method is a cost-effective and easy-to-operate beneficiation technology, which is especially suitable for processing gold tailings with higher density and coarser particle size. It utilizes the difference in specific gravity between gold and vein minerals to realize the separation of coarse and fine-grained gold in the fluid medium. Shaking table gold separation is for 2-0.037mm particle size of gold tailings, through the asymmetric reciprocating motion of the bed surface and the flushing effect of the thin layer of water flow, so that the mineral stratification and separation according to the density; with its stable and reliable selection of gold, high sorting precision, can obtain high-grade concentrate.
Spiral chute as the main equipment for gold separation in chute, suitable for processing gold tailings in the range of 2-0.02mm coarse particle size, the use of inclined water flow and gravity and other joint forces of the ore particles for separation, effective separation of different specific gravity of the ore particles.
In addition, re-election is often used in conjunction with flotation or chemical beneficiation methods, especially in the presence of sulfide and chondrite concretions in the flotation tailings, re-election can effectively recover the coarse-grained gold that is difficult to be recovered by flotation.
2. Flotation is a widely used technology in gold mine tailings recovery, which effectively separates useful minerals from chert minerals by utilizing the differences in physical and chemical properties of the mineral surfaces. For tailings containing precious metals with large specific gravity such as gold and silver, even if the content is low, by regrinding to -200 mesh accounting for about 60-80%, it can ensure that the minerals are fully dissociated, thus improving the recovery rate of gold.
Cyanide leaching is a process used to recover gold from gold tailings when conventional flotation or re-election methods are not applicable. This method is suitable for gold-bearing mineral tailings with fine particle size and good dissociation. The gold and silver are dissolved out of the tailings through the affinity of cyanide for the precious metals. The leached gold is subsequently adsorbed through activated carbon, and the separation and purification of the gold sludge is realized through carbon desorption and electrowinning process, and finally smelting. The concentration of the cyanide agent and the reaction time should be strictly controlled in the cyanidation process to avoid pollution to the environment.
The re-election process of gold tailings involves a variety of methods, each of which has its own unique advantages and applicable conditions. It is necessary to comprehensively consider the mineralogical characteristics of the tailings, the types and contents of metals and nonmetals contained, and the economic benefits and other factors. Aiming at tailings with different characteristics, suitable methods are selected or used in combination with other processes to realize the efficient recovery of gold from gold tailings.
