Every business operation that obtains its primary products from beneath the earth’s crust can have its operations impacting negatively or positively on environmental sustainability. Mining operations in this regard are not of exception as their process directly affects the environment in several ways. This notwithstanding, the hunger for the precious metal (gold) due to its contribution to wealth, employment and the overall economy of countries globally have paved the way for some of these concerns to be overlooked.
It is worthy to note and acknowledge that many of the methods that are used to extract gold from ore sediments are sometimes healthy and at other times unhealthy. This bores down on giving credence to the lives of workers and their families and the immediate communities where gold mining operations take place.
The chemicals used and released at the end of some of the methods of gold extraction are poisonous to employees and the environment. This means that employees are exposed to serious health hazards and the environment is subjected to far reaching degradation.
It is the responsibility of every mining company that respects lives and also gives credence to environmental sustainability to ensure that the methods it uses to free gold from ore although leads to increased gold yield does not in any way compromise on the health of its employees and their families as well as the sustainability of the surrounding environment.
There are various methods to free gold particles from their solid mantle in the ore extracted underground. In this article, we are going to discuss the most important healthy and unhealthy methods of freeing gold from ore.
This method of gold liberation is considered as the oldest technical method of extracting gold. This is because the method has been in existence since antiquity. With this method, the ore containing gold is first crushed into fine sand particles. When the fine sand particles are successfully achieved after grinding, mercury is added to it. Particulate properties of gold allow it to easily bind to the surface of mercury. The gold enriched mercury forms a silvery shining alloy solution, which is termed the “AMALGAM”. The amalgam settles and gathers at the bottom of the mixing bucket/bowl and is easily separated from the other minerals. Afterwards, the amalgam is heated until the mercury vaporizes, leaving behind the raw gold mineral.
Although this method is considered to be cheap, easy and effective, it reduces gold quality and also exposes workers and their families to serious health hazards. The most severe form of hazards to humans associated with this method is lead poisoning. The amalgam method also destroys the environment and its natural endowments such as plantations and aquatic life.
Cyanide Leaching Method
This type of gold liberation is mainly used in places where the earth has a very large amount of gold deposits. This phenomenon is what makes industrial mining investment very profitable.
The cyanide leaching method requires that the gold-bearing ore be first grinded into very fine sand particles. Thereafter, the sand particles are mixed with sodium cyanide solution. The mixture is then piled in heaps, columns or stored in tanks. The acid chemical (sodium cyanide) detaches the gold from the sand particles and transports it in an acid seepage fluid in a chemically bound form. Subsequently, the gold is fished out of the leach solution by adding zinc dust, which is then washed out of the muddy substrate and finally dried. The raw gold recovered from this process is later refined into fine gold.
Even though cyanide leaching leads to an increased amount of gold recovery from ore, it is highly dangerous to the health of humans and the surrounding environment. This is because the process releases highly poisonous, easily flammable hydrogen cyanide acid, which presents significant health hazards to humans and the natural environment.
The Elecrowinning method is currently one of the most frequently used methods of separating gold from ore. The method involves gold extraction without the use of poisonous substances. In this method, advantage is taken during the extraction of other precious metals such as iron, copper, tin, lead or zinc where small quantities of gold are found in the extracted rock.
In the process of electrolytic cleaning of rock sludge, the anode activates the gold particle bearing rock sludge while the cathode is made of a piece of pure metal. During electrolysis, the gold in the raw rock material is not dissolved and collects as sludge under the anode. Together with gold, other precious metals such as iron, zinc, copper, etc., concentrate in the anode sludge are easily skimmed off. Afterwards suitable processes are used to separate the individual precious metals from each other.
This method is healthy to humans and environmentally friendly.
In the Borax method of gold separation, the ore containing gold material is placed in a melting crucible and sodium borate is added to it. The borax makes the melting point of the ore mixture to sink downwards and makes the molten mass more fluid. The low melting point in this regard, enables gold to be extracted using a cost effective, low power heat source to bring about melting. The gold settles at the bottom of the crucible, whereas all other oxides rise to the top.
This method is also healthy to humans and ensures environmental sustainability.
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