The majority of the gold mined in the world is extracted from gold ore, which are rocks that contain small amounts of gold particles mixed in with solid rock, according to HowStuffWorks. Gold may also be mined from small deposits in riverbeds or beaches, but these are becoming extremely rare.Continue Reading
The process for extracting gold from ore is quite complicated, explains HowStuffWorks. First, the gold-bearing rocks must be crushed into a fine powder and then mixed with water. This mixture, known as pulp, then passes through a series of leaching tanks where chemical solvents like cyanide are used to dissolve the gold from the rock. Carbon is then added to the solution and attaches to the gold particles.
The carbon and gold particles are filtered out and then separated by using a hot caustic solution, according to HowStuffWorks. Next, the gold is removed from the leaching solution by a process known as electrowinning, which passes a strong electrical current through the solution. The gold particles are attracted and collect on the negative terminal. This in turn is melted, after which a flux is added that separates the gold from the metal terminals. The gold is then sent on to refineries where it can be further refined until it is finally pure.
More than 90 percent of the gold in the world has already been mined, which is why such complicated measures are needed to extract it from ores, notes the World Gold Council.Learn more about Industries