The Gold Industry
Gold is the most malleable and ductile of all the metals. It can easily be hammered to a thickness of 0.000013cm and 1g can be drawn into a wire 3.5km long. Gold has been mined for thousands of years, not only for its beauty, but also because it is the easier to work with than other metals. Gold melts at 1064° and boils at 5086°.
Extensive deposits of gold are commonly found under waterways and near small rocky outcrops. If a mining company gets a licence to mine an area for gold, there are several ways that they could extract the gold from the ground. The two most common are hydraulic mining and cyanide mining.
The hydraulic method consists of directing a powerful stream of water against some gold bearing rocks, gravel or sand. This breaks down the material and washes it through specially designed pipes in which the gold (being heavy) settles, while the other lighter material floats away. Miners can only use this method if there is a good supply of water nearby. If there isn’t they can use the cyanide method.
After the gold bearing rocks are mined and crushed by machines, the gold is extracted from the rocks by putting the material in cyanide. The gold combines with the cyanide allowing it to be separated from the ore. The reaction between the gold and sodium cyanide is: 4Au + 8NaCN + O2 + 2H2O → 4NaAu(CN)2 + 4NaOH. The aurocyanide is then processed to separate the gold from the cyanide.
The miners have several hazards to deal with when using either of the methods. When used wrongly, the mining machines can be very dangerous. This is why all gold miners are trained properly and wear protective gear such as earmuffs and helmets.
Cyanide is the major hazard for gold miners. One teaspoon of a 2% solution can kill an adult human. Cyanide leaks and spills are common in the industry which is why workers wear protective suites to protect themselves from being poisoned. However it isn’t only the...