Gold mining in countries such as South Africa where workers are usually exploited involves methods such as hard-rock mining, panning, and, and by-product mining. In modern gold-mining in devolved countries, first large chunks of gold-bearing rock are removed from the ground and then it is broken down into smaller pieces. Large machines that are known as crushers make the small pieces of the ore even smaller so that it is no larger than road gravel. The gravel-like material is then put into rotating drums filled with steel balls where the ore is ground into a fine slurry or powder. The mill operators thicken the slurry with water to form a pulp which then goes through a series of leaching tanks. Leaching dissolves the gold out of the ore using chemicals (most commonly cyanide mixed with oxygen). When those chemicals react the gold in the pulp dissolves and workers will then put small carbon grains into the tank which the gold will adhere to. The gold-bearing carbon is then filtered out of the pulp and goes through a vessel where a hot caustic solution separates the gold from the carbon. Finally, the gold-bearing solution is ready to go through an electrical current which will remove the gold from leaching chemicals. Workers pour the solution into a container called a cell that contains positive and negative terminals that deliver the charge. The gold will collect onto the negative terminals.
The gold is then gone through another process called smelting where the negative terminals are melted in a furnace that is about 2100 degrees F. A chemical called flux is added to the molten material so that the gold can be separated from the metal that was used to make the terminals. The flux is then poured off and then the melted gold can be poured into moulds to form solid gold bars. Modern gold extracting processes usually result in 99.9% pure gold. The process of extracting is finally over but the gold bars will be sent to refineries all over the world for further processing into other things like jewellery.
