Gold has a high resistance to corrosion and is the most malleable and ductile metal. This precious metal does not exist in nature in its pure form.
So from where and how is gold extracted? Let’s find out in more detail.
Gold in its natural form contains traces of mercury, silver, iron, copper etc. Gold is found in its ores such as calaverite, sylvanite, nagyagite, krennerite and petzite. Pure gold that is extracted from an ore shows a bright golden yellow colour. The ores of gold may exist in different colours like reddish yellow, black, dark brown etc. The ore can be defined as a naturally occurring mineral that contains a valuable mineral or metal. The metal or mineral is extracted from the ore after mining. Ores may be present in the form of open-pit or underground mines. A large piece of the ore may only have low gold content in it.
Extracting gold from its ore: At first, the gold-bearing rocks are removed from the ground. For refining, gold ore can be washed at the mine and then sent to the mill. Then the large pieces are broken down into smaller chunks. Chemicals like cyanide are used in various ways to extract gold from its ore. In the first method, the fragments of gold ore are disposed of into a weak cyanide solution, and zinc is added to it. It results in a chemical reaction which separates gold from its ore.
In the second method known as the carbon-in-pulp method, the ore is converted into slurry or powder. It is mixed with water, and then cyanide is added. Small carbon granules are then introduced into this mixture which gets bonded with the gold. Gold can be separated and taken out by putting the carbon and gold bonded particles in caustic carbon solution.
Another method to separate gold is the heap leaching method. Cyanide spayed over the ore placed on open-air pads. After several days, the deposits leach down into an alkaline solution. Gold then later recovered from this leach.
Gold can also be separated from its ore bypassing the ore over plates that are coated with mercury. The gold and mercury together form an amalgam. Then the amalgam is heated until mercury gas is boiled off and gold is left.