The methods used for gold mining are evolving as technology produces new techniques to simplify and lower the costs associated with extracting and processing gold. Companies that employ a combination of the best gold mining methods
are able to:
One of the most widely used methods for gold extraction involves the use of gravity as a separation tool. Gravity can be used to help separate elements of differing weights from a mixture of materials. It is easily implemented with the use of a Gravity Separation Table and has a relatively high efficiency rate while being one of the most cost-effective methods. This method also poses minimal safety issues to workers and the environment, due to the absence of chemicals.
Gravity separation uses the basic principles of gravity to separate different substances based on weight and reaction to the naturally powerful forces of gravity. It is basically a larger scale and mechanical adaptation of the traditional panning process. A woven mesh and low-pressure airflow are also commonly used to aid the separation process of the elements from the rest of the mixture. The inclination of the table makes it possible for the higher weight substances, such as gold, to move to the inclined side of the table.
The principles of many minerals as being hydrophobic materials are exploited with the use of the flotation method. The term hydrophobic is used to describe a very strong resistance to certain liquids, most commonly electrically charged water. Gold is an especially hydrophobic element and so repelled by water that it will float on top of the water in an effort to minimize contact.
The flotation process typically occurs in specialized tanks that can produce a mixing action (known as froth flotation) and infuse air to further facilitate the hydrophobic minerals separating and floating on top of the rest of the mixture. Collector agents are commonly utilized in froth flotation to increase the natural hydrophobic resistance and separation of the minerals. Oil is one of the most popular collector agents.
Cyanidation is the most popular method of gold extraction in the world. This process is especially useful as a technique to efficiently extracting gold from lower density ore. A solution of sodium cyanide or potassium cyanide is effectively used to dissolve gold. In order to achieve this, the ore is finely ground to maximize exposure to the cyanide solution and the solution is then separated from the other unwanted materials. The solubilized gold is then recovered and often further refined.
The cyanidation process uses potentially toxic chemicals, but it is very safe when executed in a controlled environment with all waste materials handled and disposed of properly.