Cyanide gold extraction technology
Cyanide gold extraction technology can be promoted and applied around the world. The reason is that the recovery rate is high and the gold production is large. It can realize the real estate gold and avoid the various shortcomings of long-distance transportation of gold ore. As a result, the unit production gold cost is bound to decrease, which is conducive to improving the economic efficiency of enterprises.
However, after more than 120 years of development, the quality of gold ore, labor costs, environmental costs and other factors have changed a lot. Is the cost of cyanide gold extraction technology really low? In addition, in addition to cost factors, the face is getting heavier. The environmental pressure, the gold industry is thinking about where the gold technology will go.
"Three wastes" processing costs are high
The cyanide gold extraction process used in gold production will cause pollution such as waste water, waste gas and waste residue in the production process. If it is not treated, it will seriously damage the environment and endanger people's health.
At present, the main methods for treating cyanide-containing wastewater include chlorine oxidation method, acidification recovery method, hydrogen peroxide oxidation method, complex method, microbial method, activated carbon adsorption method, etc.; methods for treating exhaust gas pollutants include catalytic reduction method, solvent absorption method, etc. The cyanide in the cyanide-containing waste residue is treated by bleaching powder oxidative decomposition, flotation, precipitation, and the like.
It can be said that the “three wastes†treatment technology produced during the cyanide process of gold extraction is relatively mature, especially the cyanide-containing wastewater treatment process, but it is these various “three wastes†treatment technology costs that occupy a large cost of gold production. Part of it.
Low total cost per ton of mine
In the process of cyanide gold extraction, there are many influencing factors, and the complexity is even worse with the increase of difficult metallurgy and low grade ore. However, in general, the main factors affecting the amount of gold extraction are the type of cyanide reagent and its concentration, the concentration of oxygen, the pH of the slurry, the temperature of the slurry, the concentration of the slurry and the concentration of the slurry, the leaching time, and the application of the protection of alkali.
These factors directly affect the comprehensive cost of cyanide gold extraction. After more than 120 years of development, the production technology has matured, and gold producers can control the above-mentioned factors indicators in a reasonable range, thus making the comprehensive production cost of cyanide gold extraction. Relatively low.
Although the three waste treatments account for a large part of the cost, cyanide gold extraction technology is currently the cheapest production method from the vertical comparison of time and the horizontal comparison with non-cyanide gold extraction technology. The sodium cyanide, which has a large immersion ability and chemical stability, and is inexpensive, is particularly favored.
Zhang Huawu, general manager of Sunit Jinyu Gold Mining Co., Ltd. said: "Our company's beneficiation process is the adsorption of all mud cyanide carbon slurry, and has always adhered to the 'cost leadership' strategy, continuously reducing costs and increasing efficiency, although the low grade of ore is restricting us. One factor, but the combined cost of tons of mines has not increased relatively."
Future environmental costs will be heavy
After more than 120 years of development, cyanide gold has become a mature technology. Although it has the advantages of low cost, clear technical principle and high recovery rate compared with non-cyanide gold, it has low ore grade. Under the realistic pressures such as the difficulty in selecting ore and other mineral resources, and the increasingly strict environmental protection requirements, the penalties are increasing.
The “National Hazardous Waste List†(2016 edition) issued by the Ministry of Environmental Protection will include gold-raminated cyanide tailings in hazardous wastes and will impose a green tax of 1,000 yuan/ton. "So, it will cause a devastating blow to the gold industry," said Zhang Yongtao, vice president and secretary general of the China Gold Association.
Yu Jianbo, deputy director of the Jilin Provincial Gold Administration, also expressed concern about the environmental costs incurred by the cyanide gold extraction technology. He said: "Because the state has higher requirements for the environmental protection of 'three wastes', the state has introduced new policies and plans to levy environmental taxes in the '13th Five-Year Plan.' This will inevitably lead to an increase in production costs for gold producers. If cyanide is not handled well, it will be severely punished."
Liu Huaili has the same feelings. He said that although cyanide gold extraction is a mature process, including the gold extraction process and the later wastewater waste treatment, as long as the cyanide is applied and the waste water residue is treated, the environmental impact of cyanide gold extraction will be Very small. "But the overall development direction is to develop less cyanide, non-cyanide, less poison, and low toxicity, and to minimize the use of cyanide, because cyanide is a highly toxic chemical controlled by the state, which is equivalent to explosives and detonators. In the event of a leak or other accident, the consequences will be unpredictable," he said.
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