Gold is a metal that is valued at all times

Gold is a metal that is valued at all times
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Gold was one of the first metals that man began to use, and jewelry was made from it even at a time when stone and wood were the main materials.

All this is due to one property – the element is often found in nature in almost pure form, nuggets.

For a long time, gold was only a means of payment and a material for jewelry. Over time, metal has become indispensable in medicine, electrical engineering, weapons production and other sectors of the economy of all countries of the world. Despite the replacement of monetary standards, any country is trying to secure a certain gold reserve.

However, where did this chemical element come from (in the table of chemical elements of D. I. Mendeleev, gold is designated as Au (aurum) at number 79), how is it mined and used?

What gold looks like: chemical and physical properties

Gold is a noble metal, many have heard this name, but what does it mean?

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Chemical properties. As a chemical element, it practically does not react, and is not affected by aggressive substances. In short, gold does not oxidize, making it an ideal material for many industries.

physical properties. What does gold look like? In its pure form, it is a rich yellow, rather soft metal, at the same time dense, which determines the considerable weight of the products.

Nickel – the metal of the future?
Nickel – the metal of the future?
If you take a kilogram of gold and make a ball out of it, it will be a sphere with a diameter of only 46.2 millimeters!

Pure material is very easy to process, easy to melt (melting point 1064°C), forge (very thin sheet can be made) and drawn.

Insignificant hardness is the main disadvantage, which is eliminated by adding impurities to the metal: silver, copper, platinum and steel. This is how different types of gold appeared.

Gold types

There are two main types of gold – banking and jewelry.

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In the first variant, the purity of the metal is very important, where the main standard of 999 samples is adopted. This means that such a sample does not contain impurities of other elements. Such ingots are kept in state reserves and sold by banks as investments.

For jewelry gold, strength and durability are important. Therefore, pure gold is not used in jewelry because of its softness. Therefore, such varieties as yellow, white, red, pink, gray and even green gold appeared.

Oil is black gold
Oil is black gold

Additives and the percentage of all elements in jewelry gold determine its price. The amount of gold indicates the sample, it shows how much precious metal is in the product. For example, the most common 585 sample means that the product contains 58.5% pure gold, and everything else is impurities.

Where is gold used?

Until the 20th century, yellow metal was exclusively a means of payment and decoration. And only with a jump in technological progress, it was increasingly used in industries. But even today, all significant volumes are concentrated as reserve stocks of means of payment of states.

10% of all available gold is in the form of industrial products. The main direction of production, where it is used, remains electrical engineering. Also, the element is indispensable in the production of neutron bombs, nuclear fusion, and in the space industry.

A very thin layer of precious metal can be used in windows to reflect infrared radiation for energy saving purposes.

Gold is indispensable in medicine, especially dentistry and pharmacology.

Platinum: history of metal discovery, areas of application, mining technologies
Platinum: history of metal discovery, areas of application, mining technologies

Popular mobile communication uses this element, each SIM card has a thin gold plating.

The main use of the precious metal is the gold reserve of the state, about 32,000 tons of precious metal are stored in all the gold and foreign exchange reserves of the world.

The remaining volumes are personal investment funds of residents and jewelry.

Theories of the origin of the yellow metal are interesting. According to one hypothesis, the element was formed as a result of the destruction of neutron stars and subsequent accumulation on our planet. And according to another theory, gold was brought several billion years ago by asteroids. In any case, all the available reserves of the precious metal on Earth were formed a very long time ago – 3 – 3.5 billion years ago.

Gold mining

100-150 years ago, in the absence of knowledge about the origin of the yellow metal, its mining was comparable to gambling. Today, having accurate understanding of the formation of gold in certain rocks, its mining has reached the industrial level with accurate data on how much of the precious element can be removed from each deposit.
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In the entire history of gold mining in the world, about 160 thousand tons of yellow metal have been obtained. And the main part of this mass was extracted during the last 100 years.

Famous gold deposits

The largest deposits and developments in gold mining are several mines: Muruntau (Uzbekistan), Grasberg (Indonesia), Goldstrike (USA), Cortes (USA), Pueblo Viejo (Dominican Republic). The volume of metal mined in these places ranges from 60 to 30 tons per year. There are also two largest first gold deposits that are not being developed at the moment: Pebble Deposit in the US state of Alaska and Natalka Kolyma – Russia.

Aluminum – winged metal
Aluminum – winged metal

Deposits are considered profitable for development, where the composition of gold in the rock is 2-5 grams per ton of rock. Today, these standards are constantly being revised. For example, the Natalka deposit is currently being prepared for development, and gold mining will begin in the near future.

Where is gold mined?

Where is gold mined and how are rich rocks found? Extraction of the noble metal occurs in two main types of deposits: primary and placer. What’s the difference between them?

Primary deposits are gold-bearing rocks that are brought to the surface from quarries or mines. The most common is a quarry mining method. Such deposits should be sought in regions with a rich history of mountain building and volcanic activity, since it is the processes of melting and movement of rocks that form deposits of precious metals. The main volumes of gold mined today are obtained from primary deposits.

Iron ore – the basis of modern industry
Iron ore – the basis of modern industry

Placer deposits of gold in nature today are very depleted. They are gold-bearing crushed rocks along the banks of rivers and streams. Formed as a result of the destruction and erosion of primary deposits, followed by the transfer and deposition of gold particles. A feature of such deposits is the presence of native metal.

The largest nugget in history was found in Australia in the second half of the 19th century, weighing about 90kg of pure gold. The second largest weighed approximately 70 kg. The Russian record holder among nuggets weighed 36 kg.

Today, gold mining is a rather lengthy and labor-intensive process that requires the processing of huge masses of rocks to obtain even a small amount of precious metal.

How is gold mined?

On our planet, gold can be found everywhere, it is present even in river and sea water. However, often the concentration is so negligible that the extraction of the element is simply not economically feasible.

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Initially, the main method of extracting the precious metal was the development of placers. Extraction was carried out by a very primitive method, by washing the rock mass in a special tray by hand. Since gold is heavier than many rocks, it settled on the bowl. Since ancient times, mining has been carried out in mines. How is gold mined today, what technological processes are used to extract it from the rock?

To this day, in the deserts of Egypt, ancient adits, reaching a depth of 100 meters, where gold was mined 2000 years ago, have been preserved.

In the modern mining industry, all developments are mechanized and carried out with the involvement of specialized equipment.

The process chain for the development of placers is as follows:

  1. diversion of the riverbed;
  2. overburden (removal of the upper layer of rocks);
  3. extraction of gold-bearing rock;
  4. flushing;
  5. cleanup;
  6. enrichment;
  7. remelted.

In cold regions, such mining is seasonal, and in winter, washing stops.

Coal: the origin, properties and classification of coal
Coal: the origin, properties and classification of coal

Mass production is carried out at the development of primary deposits by open (quarry) or closed (mine) method.

The gold-bearing rock also goes through the stage of extraction to the surface, grinding, enrichment and separation of gold from impurities.

Methods of extracting gold from rock

The whole process of extracting gold is based on its physical and chemical properties. One of the most ancient is the use of mercury. In this way, precious metal particles were separated back in the days of Ancient Rome.

The rock was mined and crushed, after which mercury was added to it. It formed an alloy (amalgam) with gold-bearing mud. Next, the mercury was distilled off, and the sludge was put into processing. This method of gold mining is possible only in very rich deposits, today it is practically not used.

Liquefied natural gas: global production and technology
Liquefied natural gas: global production and technology

Gold is separated by gravitational differentiation, when the mined rock is crushed with cast-iron balls in mills and sent to a centrifuge. Under the influence of centrifugal force, heavy particles of the precious metal are separated from the main rock.

There are other techniques based on the chemical properties of gold, such as cyanidation or leaching.

The noble metal is also searched for in the dumps of old mines. An elementary way of such surveys is the use of modern metal detectors.

Gradually, known deposits are depleted, and companies begin to develop those deposits that were previously recognized as unprofitable. This contributes to the development of gold mining and extraction technology.