In everyone's impression, gold is a precious metal, stored in the central banks of various countries and worn on the body of handsome men and women, but the greater use of gold is industrial applications, because its conductivity and ductility are very good, and very stable, as switch contact, signal transmission and CPU manufacturing in the electronics industry, etc., and it is very rare, which makes the price of gold high!
But in fact, there is not a lot of gold on the earth, if all the gold on the earth is mined and distributed to everyone equally, it is estimated that each person can get 5.5 million tons, so why is gold still so rare?
<h1 class="pgc-h-arrow-right" data-track="50" how much gold is there on Earth >? </h1>
Would you believe someone telling you that all the gold mined on Earth from ancient times to the present is a 21-meter cube? The scale in the figure below is not much larger than a villa!
About 191,000 tons, that's all the gold mined by humans, with a total value of about $12 trillion or so! According to the british metal focus company in 2018 data, the global gold reserves are about 56,770 tons, while the proven amount is 129,460 tons, a total of 186,230 tons, according to the global gold production in 2018 about 3503 tons, about 65 years!
But in fact, the gold on the earth can never be mined, although from the gold content of the entire earth is not a lot, the abundance of gold in the crust is only 0.0004× 10^-6, but the mass of the crust is too large, the gold in the crust is at least 60 trillion tons!
Abundance of elements in the earth's crust
More gold is distributed in the mantle and core, and the core is theoretically much more abundant than the crust, with more than 99% of the gold in the core. If the core and mantle and the gold in the earth's crust are all extracted, the total amount is close to 400 million tons, even if calculated according to the earth's population of 7.9 billion, each person can be divided into 5 million tons, which is about a cube of 64 meters long!
This is everyone's Oh, if these laying on the surface of the earth can produce a 4-meter thick golden earth, if the aliens look at the solar system in Proxima Centauri, it is estimated that they can blind their dog eyes! But in fact, I still can't see it, you think too much Ha!
<h1 class="pgc-h-arrow-right" data-track="51" > Why is gold so hard to mine? </h1>
Although there is so much gold on the earth, and some people have picked up dog head gold or directly panned for gold, in fact, this opportunity is very rare, and most gold mining is very difficult! The first point is that there are too few veins of gold, and the other point is that even if it is a gold mine, its grade is not high, such as:
For large open-pit gold mines, the ore gold content must be greater than close to 1 g/ton to have mining value;
In hard rock formations or underground gold mines, the gold content of the ore must be about 3 g/ton to have mining value;
But in this grade of gold ore, you can't see gold with the naked eye, which means that most of the gold ore currently mined is stone, and you can't see gold at all! When you can see the gold ore with the naked eye, the grade has reached more than 30 g/ton! Of course, it may also be pyrite, don't be deceived!
According to a 2013 data shows that the average global gold ore grade is only 1 gram/tonne, to get such a 1-2 grams of gold from a ton of gold ore, think about it is depressing! So what kind of process is it? For example, chemical beneficiation processing will go through the following process:
1. The gold ore is transported to the heap leaching site;
2. Spray sodium cyanide solution and alkali solution (sodium cyanide solution erodes the gold molecules in the mine, and the alkali solution protects the sodium cyanide solution from losing too quickly);
The soaking process can appropriately reduce the requirements for grade, even if it is less than 1g, it is profitable! The difference in the treatment of the immersion solution has derived a lot of gold extraction processes, such as the carbon slurry method using activated carbon adsorption and then using the desorption process to separate the gold in it or directly using the zinc wire replacement method, the gold is replaced by zinc into a metal state and precipitated:
2Au(CN)2+Zn=> 2Au+Zn(CN)4
Soaked cyanide for NaCN, KCN, NH4CN, CaCN2, but either is highly toxic, so the process of processing gold from ore is a highly polluting process, of course, the earliest amalgam method will also have the participation of highly toxic substance mercury, this gold is really not a good thing, but everyone likes it!
Where is the gold mine?
Except for a few open-pit gold mines, most of them are either in remote areas or deep underground, such as the South Deep gold mine in Gauteng, South Africa, which has been 3 kilometers underground, and the high temperature and humidity environment are very harsh! The Mponeng gold mine in South Africa's North-West Province is located 900 meters underground, and the gold mine grade of 8 g/t is already quite high!
Source: See watermark
When the former Soviet Union set a record for deep drilling, Kola deep drilling more than 9,000 meters, it drilled into a gold layer, which is said to be more than twenty grams /ton, but such a depth is at least now there is no technology to mine.
The depths of the earth are all gold, but human beings can only look forward to gold and sigh!
<h1 class="pgc-h-arrow-right" data-track="17" > how did gold come from? </h1>
Gold is element 79, 79 protons and 118 neutrons, also known as gold-197, friends who understand the composition of the elements know that the elements are just the accumulation of protons and neutrons, such as a proton is hydrogen, two protons are helium, three protons are lithium, and the back periodic table can be!
Gold atoms
Different neutron numbers will form different isotopes, and there are three ways to produce elements, namely:
1, continuous nuclear fusion, proton + proton + proton, element number is high...
2, slow neutron capture β decay, elements need to constantly +1
3, fast neutron capture β decay, element ordinal number + n
The first can only go to iron and nickel, the second can not produce heavy elements, to produce gold, only the third fast neutron capture, it has two ways, one is the fast neutron capture when the supernova explosion, the other is the neutron star merger, so the gold on the earth generally comes from the supernova explosion, after all, the neutron star merger nebula is really rare, and the probability of possible formation of star systems is low.
And when the earth was formed, the heavy elements were sunk into the core of the earth, of course, most of them were iron-nickel, and it was these elements that formed the earth's magnetic field in the core of the earth, of course, the thermogenic mechanism of the radioactive elements in the heavy elements contributed the other half.
<h1 class="pgc-h-arrow-right" data-track="68" >Exheder reading: Gold or diamonds, which is more valuable? </h1>
Gold is the equipment of local tycoons, and diamonds are "eternal, eternal" high-end jewelry, but in fact, diamonds have long been artificial, and man-made diamond defects are few or almost non-existent, but gold can not be artificial or the cost is extremely high, from this point of view, diamonds do not have to preserve value or depreciation rate is very high!
Gold is not, it will only fluctuate with the international market, from this point of view, gold is the real "value" of things, and diamonds may really be replaced by artificial in the future! Of course, many well-known jewelry brands now have artificial diamond jewelry for sale, and the price is much more affordable than natural ones!