A gold refinery is a processing plant that uses a sophisticated smelting process to extract gold and other precious metals from rocks, minerals, chemicals, manufacturing scraps and used jewelry. The process of mining, smelting and refining precious metals is known as metallurgy.
Gold refining began between 6000 and 3000 B.C. in Mesopotamia or Syria. Ancient methods of extracting gold included using mercury, and crushing, washing and applying heat. A chemical process using a cyanide solution is now the most common method.
Almost 80 percent of mined gold becomes jewelry. The rest is used in medical applications, dental work and electronics. Most gold jewelry is mixed with metal alloys, including copper, silver and palladium. Only 24K gold is pure gold.