Contents
The stages of gold extraction and mining
Gold goes through several stages during its extraction and mining, as follows: [1]
- Getting to gold: The location of gold deposited underground inside the rocks is located, and accessed by digging or blasting, or shoveling the surrounding rocks, where miners dig columns in the ground using small explosives, and then remove the gold ore from the rocks, collect it, and transport it To the treadmill.
- Removal of residual sediment: sediments that contain gold are removed and are known as permeate by using hydraulic mining, or dredging, where the force of gravity is relied upon as the main screening force, by using a machine called the hydraulic giant in the first method, where gold is exposed to a strong water current to wash and sweep it. In order for it to be deposited in special pits, as for the dredging process, the same technique is used, but with different shovels and buckets, where large quantities of sand and gravel bearing gold are extracted using huge machines such as shovels, and it is worth noting that many countries have banned the hydraulic mining process as they are Land is destroyed and rivers pollute.
- Grinding the extracted gold: The gold is transferred to mills after washing and filtering, where it is mixed with water and soil, and the resulting mixture is placed in a ball mill that contains polishing.
- Separating gold from the ore: This is done by following the buoyancy method that relies on separating gold using certain chemicals in addition to air, where the gold ore is placed in a solution that contains a foaming agent that binds to the gold and forms an oily layer that adheres to air bubbles, in addition to a mixture of organic chemicals that Other pollutants are prevented from sticking to it, and after that the solution is ventilated, thus blowing air bubbles, which leads to the gold being attached to them, and then the bubbles float and the gold is skimmed from the surface. As for the use of chemicals to separate the gold, the gold ore is placed in a tank containing A dilute cyanide solution, and then zinc is added to the tank, to a chemical reaction that leads to the precipitation of gold from its ore, and then the gold deposit is separated in the filter press.
- Gold smelting : the gold is smelted if it is not pure enough, where the gold is heated using a special chemical, where it is associated with pollutants and floats on the melted gold, to be cooled after that and poured into molds.
Gold extraction using starch
Extracting gold with cyanide is dangerous, because it produces highly toxic by-products, and a new method has been discovered by the researcher Zichang Liu to extract gold, using cornstarch instead of cyanide, where he mixed a solution of gold bromide with a solution of sugar starches known as cyclodextrins. The product of the reaction was needles of gold and a mild alkaline salt that could be easily disposed of, in contrast to the harmful cyanide residues. [2]
History of gold extraction
The process of extracting gold is known as the preparation and processing of raw materials that make up gold for use in various products, and gold mining and purification processes began during the sixteenth century, during the colonization of South and Central America before moving to Europe, and large gold deposits were discovered in Brazil, and on The eastern slopes of the Ural Mountains in Russia, in the early eighteenth century, and in 1840 large alluvial deposits were found in Siberia. [3]
References
- ↑ "Gold-How Products Are Made" , www.encyclopedia.com , Retrieved 28-9-2018. Edited.
- ↑ IAN STEADMAN (20-5-2013), “'Green' gold extraction method replaces cyanide with starch” , www.wired.co.uk , Retrieved 9-28-2018. Edited.
- ↑ James Edward Hoffmann (7-2-2008), "Gold processing" , www.britannica.com , Retrieved 9-28-2018. Edited.
