Gold is an extremely rare ore. Geological survey reports state that the average concentration of gold in the Earth’s crust is only 0.005ppm. It is found in rocks at very low concentrations.
The technology of extracting gold from its ore is highly expensive, due to the fact that gold mining companies have to process large quantities of ores to obtain small results.
Finding Gold Ores
Gold is found in different parts of the Earth and sea - but in very low concentrations. The concentration of gold in sea is comparatively more than that in the Earth’s crust. It is available in significant quantities in quartz veins, and in the crevices of rocks.
Over the surface, there is alluvial gold, deposited by running waters. Gold will usually concentrate in placer deposits, where valuable minerals get accumulated naturally.
Gold Mining Process
Gold mining is the process of extracting gold from the gold ores. Several methods by which gold can be mined from the Earth are as follows:
- Placer mining – It is the process of extracting gold from the placer deposits
- Panning – It is a manual technique, where a pan containing sand and gravel with gold is submerged in water and shaken to separate the gold
- Sluicing – This process uses a sluice box to extract gold from placer deposits
- Hard rock mining – It is one of the most widely used types of gold mining. This process extracts gold deposited within rocks
- By-product gold mining – In this process, considerable amounts of gold is extracted as a by-product, along with other metals
Processing Gold Ores
Gold accumulated within a sulfide mineral deposit can be processed using refractory ore treatment, which involves the fine grinding of sulfide materials, followed by the oxidation process. Free milling gold ores, on the other hand, are processed by a heap-leach process.
The amount of gold adsorbed by activated carbon is recovered by a series of processes, including elution, precipitation, and smelting.
Today, the process of mining gold is very challenging. In the broadest terms, the process of gold mining involves the exploration, drilling, geological assessment, funding, development, extraction, processing, and delivery of pure gold.
Owing to the inertness of gold, nearly 80% of gold within ores is in its elemental form. This requires more drilling to produce every single ounce, followed by several processes of extraction and purification. All this adds to the increasing cost of gold mining which, in turn, affects the supply of gold.