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Ancient technology resurrected: How does amalgamation remain popular in small-scale mining?
The extraction of gold is a long and technically complex process. Since the 20th century, the cyanide method has become the mainstream gold extraction technology, while the amalgam method still exists in small-scale mining. The continued use of this traditional method not only raises concerns about its environmental impact, but also makes us rethink the direction of modern mining.
Gold extraction typically involves chemical processes to extract the metal from rare earth ores, and the efficiency and compliance of these processes have always been significant challenges for the industry.
Gold exists primarily as native metal, usually alloyed with silver to form a form called electrum. In alluvial deposits on the surface, gold is usually found in the ore as larger lumps or tiny particles. In addition, there are some rare minerals such as garavistone, antimony ore and mardo stone, which also contain gold components, but these ores are relatively rare and difficult to extract.
In the process of gold extraction, the main challenge is to effectively concentrate the trace amounts of gold present. Although the cyanide process is widely used, its potential environmental pollution problems have led some small-scale miners to still choose the older amalgam method. This method demonstrates its particular effectiveness when dealing with extremely small gold particles.
According to the data, the amalgam method is still an effective extraction method in small-scale mining, but its impact on the environment cannot be ignored.
The basic principle of the amalgam method is to form an amalgam by combining with gold particles, and then heat and evaporate the mercury to obtain gold. However, the toxicity of mercury undoubtedly poses a threat to workers' health and the surrounding environment. Although this method is relatively efficient, its harmfulness has caused people to gradually turn to safer and more environmentally friendly methods.
According to some research reports, more than 100,000 pounds of mercury were released into the environment during mining activities in California in the past, causing serious soil and water pollution problems. Even today, the effects of these pollutants continue to persist, posing long-term health risks to surrounding residents and ecosystems.
Among gold extraction technologies, the cyanide method is still the most commonly used technology. The method involves mixing gold ore with sodium cyanide and then recovering the gold through a brown carbon adsorption process. However, this process may not be efficient in the case of ores containing high dissolved copper values or that are rich in copper.
The gold refining and separation process, which involves filtering the metal through chlorine gas to remove other elements, is still commonly used in large-scale metal refining.
Environmental pollution from heavy metals has led many countries to strictly regulate the use of mercury, yet its use is still common in many developing countries. This is not only because it is cheaper than the capital and equipment required for new technologies, but also because of the demand from local small-scale miners to recover gold quickly.
In addition, with the advancement of technology, new advanced gold mining technologies such as bio-oxidation and pressure oxidation have begun to receive widespread attention. These new methods aim to improve gold recovery capabilities and reduce adverse effects. However, the introduction and popularization of these technologies are often constrained by a combination of economic, technical and resource factors.
The history of gold dates back to approximately 6000 to 3000 BC, when early humans began to search for and refine it. In ancient times, the process of gold refining was already recorded in Mesopotamia and ancient Greece. With the advancement of science and technology, gold extraction and refining technology has undergone a long evolution, from simple heating in the early days to the current high-tech methods, each step reflects the accumulation of human wisdom.
At the dawn of the industrial age, the commercial application of cyanide redefined gold mining. However, the environmental problems and social impacts caused by the development of this process obviously require us to further think about related issues of sustainable development while pursuing the wealth of gold.
So, faced with these choices between ancient and modern technologies, can small-scale mining find a way to protect the environment while still producing gold sustainably?
