Is it possible to get gold from lead? How to get gold from mercury? Obtaining gold in a nuclear reactor

In 1935, the American physicist Arthur Dempster succeeded in mass spectrographic determination of the isotopes contained in natural uranium. During the experiments, Dempster also studied the isotopic composition of gold and found only one isotope - gold-197. There was no indication of the existence of gold-199. Some scientists suggested that there must be a heavy isotope of gold, because gold at that time was assigned a relative atomic mass of 197.2. However, gold is a monoisotopic element. Therefore, those wishing to artificially obtain this coveted noble metal must direct all efforts towards the synthesis of the only stable isotope - gold-197.
News of successful experiments in the manufacture of artificial gold has always caused concern in the financial and ruling circles. So it was in the time of the Roman rulers, so it remains now. Therefore, it is not surprising that a dry report on the research of the National Laboratory in Chicago by Professor Dempster's group has recently caused excitement in the capitalist financial world: gold can be obtained from mercury in a nuclear reactor! This is the latest and most convincing case of alchemical transformation.
It began as early as 1940, when in some laboratories of nuclear physics they began to bombard with fast neutrons obtained with the help of a cyclotron, the elements adjacent to gold - mercury and platinum. At a meeting of American physicists in Nashville in April 1941, A. Sherr and K. T. Bainbridge from Harvard University reported on the successful results of such experiments. They sent accelerated deuterons to a lithium target and received a stream of fast neutrons, which was used to bombard mercury nuclei. As a result of the nuclear transformation, gold was obtained! Three new isotopes with mass numbers 198, 199 and 200. However, these isotopes were not as stable as the natural isotope gold-197. By emitting beta rays, after a few hours or days, they again turned into stable isotopes of mercury with mass numbers 198, 199 and 200. Therefore, modern adherents of alchemy had no reason to rejoice. Gold that turns back into mercury is worthless: it is deceitful gold. However, scientists rejoiced at the successful transformation of the elements. They were able to expand their knowledge of artificial isotopes of gold.
The "transmutation" carried out by Scherr and Bainbridge is based on the so-called (n, p) -reaction: the nucleus of a mercury atom, absorbing a neutron n, turns into an isotope of gold and, in this case, a proton p is released.
Natural mercury contains seven isotopes in different amounts: 196 (0.146%), 198 (10.02%), 199 (16.84%), 200 (23.13%), 201 (13.22%), 202 (29 .80%) and 204 (6.85%). Since Scherr and Bainbridge found isotopes of gold with mass numbers 198, 199, and 200, it must be assumed that the latter arose from isotopes of mercury with the same mass numbers. For example:
Hg + n =Au + p
Such an assumption seems justified - after all, these isotopes of mercury are quite common.
The probability of a nuclear reaction occurring is primarily determined by the so-called effective capture cross section of the atomic nucleus with respect to the corresponding bombarding particle. Therefore, Professor Dempster's collaborators, physicists Ingram, Hess and Haydn, tried to accurately determine the effective cross section for neutron capture by natural mercury isotopes. In March 1947, they were able to show that the isotopes with mass numbers 196 and 199 have the largest neutron capture cross section and therefore have the highest probability of becoming gold. As a "by-product" of their experimental research, they received... gold! Exactly 35 micrograms, obtained from 100 mg of mercury after irradiation with slow neutrons in a nuclear reactor. This amounts to a yield of 0.035%, however, if the found amount of gold is attributed only to mercury-196, then a solid yield of 24% will be obtained, since gold-197 is formed only from the mercury isotope with a mass number of 196.
With fast neutrons, (n, p)-reactions often occur, and with slow neutrons - predominantly (n, ()-transformations. Gold, discovered by Dempster's employees, was formed as follows:
Hg + n = Hg* + (
Hg* + e[-] = Au
The unstable mercury-197 formed by the (n, ()-process turns into stable gold-197 as a result of K-capture (of an electron from the K-shell of its own atom).
Thus, Ingram, Hess and Haydn synthesized appreciable amounts of artificial gold in an atomic reactor! Despite this, their "synthesis of gold" did not alarm anyone, since only scientists who carefully followed the publications in the "Physical Review" learned about it. The report was brief and probably not interesting enough for many because of its vague title: "Neutron cross-sections for mercury isotopes". However, chance would have it that two years later, in 1949, an overly zealous journalist picked up this purely scientific report and, in a noisily market-oriented manner, proclaimed in the world press about the production of gold in an atomic reactor. Following this, in France there was a major confusion in the quotation of gold on the stock exchange. It seemed that events were developing exactly as Rudolf Daumann had imagined, who predicted the "end of gold" in his science fiction novel.
However, artificial gold obtained in a nuclear reactor was long in coming. It had no intention of flooding the markets of the world. By the way, Professor Dempster had no doubts about it. Gradually, the French capital market calmed down again. This is not the last merit of the French magazine "Atoms", which in the January issue of 1950 published an article: "La transmutation du mercure en or" (Transmutation of mercury into gold).
Although the magazine, in principle, recognized the possibility of obtaining gold from mercury by a nuclear reaction, however, he assured his readers of the following: the price of such an artificial precious metal would be many times higher than natural gold mined from the poorest gold ores!
Dempster's employees could not deny themselves the pleasure of getting a certain amount of such artificial gold in the reactor. Since then, this tiny curiosity has graced the Chicago Museum of Science and Industry. This rarity - evidence of the art of "alchemists" in the atomic age - could be admired during the Geneva conference in August 1955.
From the point of view of nuclear physics, several transformations of atoms into gold are possible. We will finally reveal the secret of the philosopher's stone and tell you how to make gold. At the same time, we emphasize that the only possible path is the transformation of nuclei. All other recipes of classical alchemy that have come down to us are worth nothing, they only lead to deception.
The stable gold, Au, could be made by radioactive decay of certain isotopes of neighboring elements. The so-called nuclide map teaches us this, in which all known isotopes and possible directions of their decay are presented. So, gold-197 is formed from mercury-197, which emits beta rays, or from such mercury by K-capture. It would also be possible to obtain gold from thallium-201 if this isotope emitted alpha rays. However, this is not observed. How to get a mercury isotope with a mass number of 197, which is not found in nature? Purely theoretically, it can be obtained from thallium-197, and the latter from lead-197. Both nuclides spontaneously with the capture of an electron turn into mercury-197 and thallium-197, respectively. In practice, this would be the only, albeit only theoretical, possibility of making gold from lead. However, lead-197 is also just an artificial isotope, which must first be obtained by a nuclear reaction. It won't work with natural lead.
Isotopes of platinum Pt and mercury Hg are also obtained only by nuclear transformations. Really feasible are only reactions based on natural isotopes. Only Hg, Hg and Pt are suitable as starting materials for this. These isotopes could be bombarded with accelerated neutrons or alpha particles in order to arrive at the following reactions:
Hg + n = Hg* + (
Hg + n = Hg* + 2n
Pt + He = Hg* + n
With the same success it would be possible to obtain the desired platinum isotope from Pt by (n, ()-transformation or from Hg by (n, ()-process. In this case, of course, we must not forget that natural gold and platinum consist of a mixture of isotopes , so that competing reactions must be taken into account in each case. Pure gold will eventually have to be isolated from a mixture of various nuclides and unreacted isotopes. This process will be costly. The conversion of platinum into gold will have to be abandoned altogether for economic reasons: as you know, platinum is more expensive gold.
Another option for the synthesis of gold is the direct nuclear transformation of natural isotopes, for example, according to the following equations:
Hg + p \u003d Au + He
Hg + d = Au + He
((, p)-process (mercury-198), ((, p)-process (platinum-194) or (p, () or (d, n)-transformation (platinum-196 The only question is whether this is practically possible, and if so, whether it is cost-effective at all for the reasons mentioned. Only long-term bombardment of mercury with neutrons that are present in the reactor in sufficient concentration would be economical. Other particles would have to be obtained or accelerated in the cyclotron - such a method, as is known, gives only tiny yields of substances.
If natural mercury is subjected to the action of a neutron flux in a reactor, then, in addition to stable gold, mainly radioactive is formed. This radioactive gold (with mass numbers 198, 199 and 200) has a very short lifespan and within a few days turns back into the original substances with the emission of beta radiation:
Hg + n= Au* + p
Au = Hg + e[-] (2.7 days)
It is by no means possible to exclude the reverse transformation of radioactive gold into mercury, that is, to break this Circulus vitiosus: the laws of nature cannot be circumvented.
Under these conditions, the synthetic production of an expensive noble metal, platinum, seems less complicated than "alchemy". If it were possible to direct the neutron bombardment in the reactor in such a way that predominantly (n, ()-transformations occurred, then one could hope to obtain significant amounts of platinum from mercury: all common isotopes of mercury - Hg, Hg, Hg - are converted into stable isotopes of platinum - Pt, Pt and Pt Of course, the process of isolating synthetic platinum is also very complicated here.
Frederick Soddy back in 1913 proposed a way to obtain gold by nuclear transformation of thallium, mercury or lead. However, at that time, scientists knew nothing about the isotopic composition of these elements. If the process of splitting off alpha and beta particles proposed by Soddy could be carried out, one would have to proceed from the isotopes Tl, Hg, Pb. Of these, only the Hg isotope exists in nature, mixed with other isotopes of this element and chemically inseparable. Therefore, Soddy's recipe was not feasible.
What even an outstanding researcher of the atom fails, of course, the profane cannot accomplish. The writer Daumann, in his book The End of Gold, published in 1938, gave us a recipe for turning bismuth into gold: by splitting off two alpha particles from the bismuth nucleus using high-energy X-rays. Such a ((, 2()-reaction is not known to date. In addition, the hypothetical transformation
Bi + (= Au + 2(
cannot go for another reason: there is no stable Bi isotope. Bismuth is a monoisotopic element! The only natural isotope of bismuth with a mass number of 209 can give, according to the principle of the Daumann reaction, only radioactive gold-201, which again turns into mercury with a half-life of 26 minutes. As you can see, the hero of Dauman's novel, the scientist Bargengrond, could not get gold!
Now we know how to really get gold. Armed with knowledge of nuclear physics, let's risk a thought experiment: we will turn 50 kg of mercury in a nuclear reactor into full-weight gold - into gold-197. Real gold is obtained from mercury-196. Unfortunately, mercury contains only 0.148% of this isotope. Therefore, in 50 kg of mercury there is only 74 g of mercury-196, and only this amount can we transmute into true gold.
At first, let's be optimistic and assume that these 74 g of mercury-196 can be converted into the same amount of gold-197 if mercury is bombarded with neutrons in a modern reactor with a capacity of 10 neutrons / (cm * s). Imagine 50 kg of mercury, that is, 3.7 liters, in the form of a ball placed in a reactor, then a flux of 1.16 * 10 neutrons will act on the surface of mercury, equal to 1157 cm3, every second. Of these, 0.148%, or 1.69 * 10 neutrons, act on 74 g of the 196 isotope. For simplicity, we further assume that each neutron causes the transformation of Hg into Hg*, from which Au is formed by electron capture.
Therefore, we have 1.69 * 10 neutrons per second at our disposal in order to convert mercury-196 atoms. How many atoms is that actually? One mole of an element, that is, 197 g of gold, 238 g of uranium, 4 g of helium, contains 6.022 * 10 atoms. We can get an approximate idea of ​​this gigantic number only on the basis of a visual comparison. For example, this: imagine that the entire population of the globe in 1990 - about 6 billion people - started counting this number of atoms. Everyone counts one atom per second. In the first second, 6 * 10 atoms would be counted, in two seconds - 12 * 10 atoms, etc. How long would it take humanity in 1990 to count all the atoms in one mole? The answer is staggering: about 3,200,000 years!
74 g of mercury-196 contains 2.27 * 10 atoms. In a second with a given neutron flux, we can transmute 1.69 * 10 mercury atoms. How long will it take to convert all of the mercury-196? Here is the answer: it will take an intense bombardment of neutrons from a high-flux reactor for four and a half years! We must make these enormous expenditures in order to eventually obtain only 74 g of gold from 50 kg of mercury, and such synthetic gold must also be separated from the radioactive isotopes of gold, mercury, etc.
Yes, that's right, in the age of the atom you can make gold. However, the process is too expensive. Gold obtained artificially in a reactor is priceless. It would be easier to sell a mixture of its radioactive isotopes as "gold". Maybe science fiction writers will be tempted to make up stories involving this "cheap" gold?
"Mare tingerem, si mercuris esset" (I would turn the sea into gold if it consisted of mercury). This boastful saying was attributed to the alchemist Raimundus Lullus. Suppose we have turned not the sea, but a large number of mercury in 100 kg of gold in a nuclear reactor. Outwardly indistinguishable from natural, this radioactive gold lies in front of us in the form of shiny ingots. From the point of view of chemistry, this is also pure gold. Some Croesus buys these bars at what he thinks is a similar price. He does not suspect that in reality we are talking about a mixture of radioactive isotopes Au and Au, the half-life of which is from 65 to 75 hours. You can imagine this miser who saw his golden treasure literally slipping through his fingers. For every three days his property is reduced by half, and he is not able to prevent it; in a week from 100 kg of gold there will be only 20 kg, after ten half-lives (30 days) - practically nothing (theoretically, this is another 80 g). Only a large puddle of mercury remained in the treasury. The deceptive gold of the alchemists!

In 1935, the American physicist Arthur Dempster succeeded in mass spectrographic determination of the isotopes contained in natural uranium. During the experiments, Dempster also studied the isotopic composition of gold and found only one isotope - gold-197. There was no indication of the existence of gold-199. Some scientists suggested that there must be a heavy isotope of gold, because gold at that time was assigned a relative atomic mass of 197.2. However, gold is a monoisotopic element. Therefore, those wishing to artificially obtain this coveted noble metal must direct all efforts towards the synthesis of the only stable isotope - gold-197.

News of successful experiments in the manufacture of artificial gold has always caused concern in financial and ruling circles. So it was in the time of the Roman rulers, so it remains now. Therefore, it is not surprising that a dry report on the research of the National Laboratory in Chicago by Professor Dempster's group has recently caused excitement in the capitalist financial world: gold can be obtained from mercury in a nuclear reactor! This is the latest and most convincing case of alchemical transformation.

It began as early as 1940, when in some laboratories of nuclear physics they began to bombard with fast neutrons obtained with the help of a cyclotron, the elements adjacent to gold - mercury and platinum. At a meeting of American physicists in Nashville in April 1941, A. Sherr and K. T. Bainbridge from Harvard University reported on the successful results of such experiments. They sent accelerated deuterons to a lithium target and received a stream of fast neutrons, which was used to bombard mercury nuclei. As a result of the nuclear transformation, gold was obtained! Three new isotopes with mass numbers 198, 199 and 200. However, these isotopes were not as stable as the natural isotope gold-197. By emitting beta rays, after a few hours or days, they again turned into stable isotopes of mercury with mass numbers 198, 199 and 200. Gold that turns back into mercury is worthless: it is deceitful gold. However, scientists rejoiced at the successful transformation of the elements. They were able to expand their knowledge of artificial isotopes of gold.

The "transmutation" carried out by Scherr and Bainbridge is based on the so-called (n, p) -reaction: the nucleus of a mercury atom, absorbing a neutron n, turns into an isotope of gold and, in this case, a proton p is released.

Natural mercury contains seven isotopes in different amounts: 196 (0.146%), 198 (10.02%), 199 (16.84%), 200 (23.13%), 201 (13.22%), 202 (29 .80%) and 204 (6.85%). Since Scherr and Bainbridge found isotopes of gold with mass numbers 198, 199, and 200, it must be assumed that the latter arose from isotopes of mercury with the same mass numbers.

For example:

Such an assumption seems justified - after all, these isotopes of mercury are quite common.

The probability of a nuclear reaction occurring is primarily determined by the so-called effective capture cross section of the atomic nucleus with respect to the corresponding bombarding particle. Therefore, Professor Dempster's collaborators, physicists Ingram, Hess and Haydn, tried to accurately determine the effective cross section for neutron capture by natural mercury isotopes. In March 1947, they were able to show that the isotopes with mass numbers 196 and 199 have the largest neutron capture cross section and therefore have the highest probability of becoming gold. As a "by-product" of their experimental research, they got gold! Exactly 35 micrograms, obtained from 100 mg of mercury after irradiation with slow neutrons in a nuclear reactor. This amounts to a yield of 0.035%, however, if the found amount of gold is attributed only to mercury-196, then a solid yield of 24% will be obtained, since gold-197 is formed only from the mercury isotope with a mass number of 196.

With fast neutrons, (n, p)-reactions often occur, and with slow neutrons - predominantly (n, ()-transformations. Gold, discovered by Dempster's employees, was formed as follows:

The unstable mercury-197 formed by the (n, ()-process turns into stable gold-197 as a result of K-capture (of an electron from the K-shell of its own atom).

Thus, Ingram, Hess and Haydn synthesized appreciable amounts of artificial gold in an atomic reactor! Despite this, their "synthesis of gold" did not alarm anyone, since only scientists who carefully followed the publications in the "Physical Review" learned about it. The report was brief and probably not interesting enough for many because of its vague title: "Neutron cross-sections for mercury isotopes". However, chance would have it that two years later, in 1949, an overly zealous journalist picked up this purely scientific report and, in a noisily market-oriented manner, proclaimed in the world press about the production of gold in an atomic reactor. Following this, in France there was a major confusion in the quotation of gold on the stock exchange. It seemed that events were developing exactly as Rudolf Daumann had imagined, who predicted the "end of gold" in his science fiction novel.

However, artificial gold obtained in a nuclear reactor was long in coming. It had no intention of flooding the markets of the world. By the way, Professor Dempster had no doubts about it. Gradually, the French capital market calmed down again. This is not the last merit of the French magazine "Atoms", which in the January issue of 1950 published an article: "La transmutation du mercure en or" (Transmutation of mercury into gold).

Although the magazine, in principle, recognized the possibility of obtaining gold from mercury by a nuclear reaction, however, he assured his readers of the following: the price of such an artificial precious metal would be many times higher than natural gold mined from the poorest gold ores!

Dempster's employees could not deny themselves the pleasure of getting a certain amount of such artificial gold in the reactor. Since then, this tiny curiosity has graced the Chicago Museum of Science and Industry. This rarity - evidence of the art of "alchemists" in the atomic age - could be admired during the Geneva conference in August 1955.

From the point of view of nuclear physics, several transformations of atoms into gold are possible. We will finally reveal the secret of the philosopher's stone and tell you how to make gold. We emphasize here that the only possible way is the transformation of nuclei. All other recipes of classical alchemy that have come down to us are worth nothing, they only lead to deception.

The stable gold, Au, could be made by radioactive decay of certain isotopes of neighboring elements. The so-called nuclide map teaches us this, in which all known isotopes and possible directions of their decay are presented. So, gold-197 is formed from mercury-197, which emits beta rays, or from such mercury by K-capture. It would also be possible to obtain gold from thallium-201 if this isotope emitted alpha rays. However, this is not observed. How to get a mercury isotope with a mass number of 197, which is not found in nature? Purely theoretically, it can be obtained from thallium-197, and the latter from lead-197. Both nuclides spontaneously with the capture of an electron turn into mercury-197 and thallium-197, respectively. In practice, this would be the only, albeit only theoretical, possibility of making gold from lead. However, lead-197 is also just an artificial isotope, which must first be obtained by a nuclear reaction. It won't work with natural lead.

Isotopes of platinum Pt and mercury Hg are also obtained only by nuclear transformations. Really feasible are only reactions based on natural isotopes. Only Hg, Hg and Pt are suitable as starting materials for this. These isotopes could be bombarded with accelerated neutrons or alpha particles in order to arrive at the following reactions:

With the same success it would be possible to obtain the desired platinum isotope from Pt by (n, ()-transformation or from Hg by (n, ()-process. In this case, of course, we must not forget that natural gold and platinum consist of a mixture of isotopes , so that competing reactions must be taken into account in each case. Pure gold will eventually have to be isolated from a mixture of various nuclides and unreacted isotopes. This process will be costly. The conversion of platinum into gold will have to be abandoned altogether for economic reasons: as you know, platinum is more expensive gold.

Another option for the synthesis of gold is the direct nuclear transformation of natural isotopes, for example, according to the following equations:

((, p)-process (mercury-198), ((, p)-process (platinum-194) or (p, () or (d, n)-transformation (platinum-196 The only question is whether this is practically possible, and if so, whether it is cost-effective at all for the reasons mentioned. Only long-term bombardment of mercury with neutrons that are present in the reactor in sufficient concentration would be economical. Other particles would have to be obtained or accelerated in the cyclotron - such a method, as is known, gives only tiny yields of substances.

If natural mercury is subjected to the action of a neutron flux in a reactor, then, in addition to stable gold, mainly radioactive is formed. This radioactive gold (with mass numbers 198, 199 and 200) has a very short lifespan and within a few days turns back into the original substances with the emission of beta radiation:

Au Hg + e[-] (2.7 days)

It is by no means possible to exclude the reverse transformation of radioactive gold into mercury, that is, to break this Circulus vitiosus (vicious circle): the laws of nature cannot be circumvented.

Under these conditions, the synthetic production of an expensive noble metal, platinum, seems less complicated than "alchemy". If it were possible to direct the neutron bombardment in the reactor so that predominantly (n, ()-transformations occurred, then one could hope to obtain significant amounts of platinum from mercury: all common mercury isotopes -Hg, Hg, Hg - are converted into stable isotopes of platinum - Pt, Pt and Pt Of course, the process of isolating synthetic platinum is also very complicated here.

Frederick Soddy back in 1913 proposed a way to obtain gold by nuclear transformation of thallium, mercury or lead. However, at that time, scientists knew nothing about the isotopic composition of these elements. If the process of splitting off alpha and beta particles proposed by Soddy could be carried out, one would have to proceed from the isotopes Tl, Hg, Pb. Of these, only the Hg isotope exists in nature, mixed with other isotopes of this element and chemically inseparable. Therefore, Soddy's recipe was not feasible.

What even an outstanding researcher of the atom fails, of course, the profane cannot accomplish. The writer Daumann, in his book The End of Gold, published in 1938, gave us a recipe for turning bismuth into gold: by splitting off two alpha particles from the bismuth nucleus using high-energy X-rays. Such a ((, 2()-reaction is not known to date. In addition, the hypothetical transformation

cannot go for another reason: there is no stable Bi isotope. Bismuth is a monoisotopic element! The only natural isotope of bismuth with a mass number of 209 can give, according to the principle of the Daumann reaction, only radioactive gold-201, which again turns into mercury with a half-life of 26 minutes. As you can see, the hero of Dauman's novel, the scientist Bargengrond, could not get gold!

Now we know how to really get gold. Armed with knowledge of nuclear physics, let's risk a thought experiment: we will turn 50 kg of mercury in a nuclear reactor into full-weight gold - into gold-197. Real gold is obtained from mercury-196. Unfortunately, mercury contains only 0.148% of this isotope. Therefore, in 50 kg of mercury there is only 74 g of mercury-196, and only this amount can we transmute into true gold.

At first, let's be optimistic and assume that these 74 g of mercury-196 can be converted into the same amount of gold-197 if mercury is bombarded with neutrons in a modern reactor with a capacity of 10 neutrons / (cm * s). Imagine 50 kg of mercury, that is, 3.7 liters, in the form of a ball placed in a reactor, then a flux of 1.16 * 10 neutrons will act on the surface of mercury, equal to 1157 cm3, every second. Of these, 0.148%, or 1.69 * 10 neutrons, act on 74 g of the 196 isotope. For simplicity, we further assume that each neutron causes the transformation of Hg into Hg*, from which Au is formed by electron capture.

Therefore, we have 1.69 * 10 neutrons per second at our disposal in order to convert mercury-196 atoms. How many atoms is that actually? One mole of an element, that is, 197 g of gold, 238 g of uranium, 4 g of helium, contains 6.022 * 10 atoms. We can get an approximate idea of ​​​​this gigantic number only on the basis of a visual comparison - the site. For example, this: imagine that the entire population of the globe in 1990 - about 6 billion people - started counting this number of atoms. Everyone counts one atom per second. In the first second, 6 * 10 atoms would be counted, in two seconds - 12 * 10 atoms, etc. How long would it take humanity in 1990 to count all the atoms in one mole? The answer is staggering: about 3,200,000 years!

74 g of mercury-196 contains 2.27 * 10 atoms. In a second with a given neutron flux, we can transmute 1.69 * 10 mercury atoms. How long will it take to convert all of the mercury-196? Here is the answer: it will take an intense bombardment of neutrons from a high-flux reactor for four and a half years! We must make these enormous expenditures in order to eventually obtain only 74 g of gold from 50 kg of mercury, and such synthetic gold must also be separated from the radioactive isotopes of gold, mercury, etc.

Yes, that's right, in the age of the atom you can make gold. However, the process is too expensive. Gold obtained artificially in a reactor is priceless. It would be easier to sell a mixture of its radioactive isotopes as "gold". Maybe science fiction writers will be tempted to make up stories involving this "cheap" gold?

"Mare tingerem, si mercuris esset" (I would turn the sea into gold if it consisted of mercury). This boastful saying was attributed to the alchemist Raimundus Lullus. Let's assume that we have turned not the sea, but a large amount of mercury into 100 kg of gold in a nuclear reactor.

Outwardly indistinguishable from natural, this radioactive gold lies in front of us in the form of shiny ingots. From the point of view of chemistry, this is also pure gold. Some Croesus buys these bars at what he thinks is a similar price. He does not suspect that in reality we are talking about a mixture of radioactive isotopes Au and Au, the half-life of which is from 65 to 75 hours. You can imagine this miser who saw his golden treasure literally slipping through his fingers. For every three days his property is reduced by half, and he is not able to prevent it; in a week from 100 kg of gold there will be only 20 kg, after ten half-lives (30 days) - practically nothing (theoretically, this is another 80 g). Only a large puddle of mercury remained in the treasury. The deceptive gold of the alchemists!

In 1935, the American physicist Arthur Dempster succeeded in mass spectrographic determination of the isotopes contained in natural uranium. During the experiments, Dempster also studied the isotopic composition of gold and found only one isotope - gold-197. There was no indication of the existence of gold-199. Some scientists suggested that there must be a heavy isotope of gold, because gold at that time was assigned a relative atomic mass of 197.2. However, gold is a monoisotopic element. Therefore, those wishing to artificially obtain this coveted noble metal must direct all efforts towards the synthesis of the only stable isotope - gold-197.

News of successful experiments in the manufacture of artificial gold has always caused concern in financial and ruling circles. So it was in the time of the Roman rulers, so it remains now. Therefore, it is not surprising that a dry report on the research of the National Laboratory in Chicago by Professor Dempster's group has recently caused excitement in the capitalist financial world: gold can be obtained from mercury in a nuclear reactor! This is the latest and most convincing case of alchemical transformation.

It began as early as 1940, when in some laboratories of nuclear physics they began to bombard with fast neutrons obtained with the help of a cyclotron, the elements adjacent to gold - mercury and platinum. At a meeting of American physicists in Nashville in April 1941, A. Sherr and K. T. Bainbridge from Harvard University reported on the successful results of such experiments.

They sent accelerated deuterons to a lithium target and received a stream of fast neutrons, which was used to bombard mercury nuclei. As a result of the nuclear transformation, gold was obtained! Three new isotopes with mass numbers 198, 199 and 200. However, these isotopes were not as stable as the natural isotope gold-197. By emitting beta rays, after a few hours or days, they again turned into stable isotopes of mercury with mass numbers 198, 199 and 200. Therefore, modern adherents of alchemy had no reason to rejoice. Gold that turns back into mercury is worthless: it is deceitful gold. However, scientists rejoiced at the successful transformation of the elements. They were able to expand their knowledge of artificial isotopes of gold.

The "transmutation" carried out by Scherr and Bainbridge is based on the so-called (n, p) -reaction: the nucleus of a mercury atom, absorbing a neutron n, turns into an isotope of gold and, in this case, a proton p is released.

Natural mercury contains seven isotopes in different amounts: 196 (0.146%), 198 (10.02%), 199 (16.84%), 200 (23.13%), 201 (13.22%), 202 (29 .80%) and 204 (6.85%). Since Scherr and Bainbridge found isotopes of gold with mass numbers 198, 199, and 200, it must be assumed that the latter arose from isotopes of mercury with the same mass numbers. For example: Hg + n =Au + p Such an assumption seems justified - after all, these isotopes of mercury are quite common.

The probability of a nuclear reaction occurring is primarily determined by the so-called effective capture cross section of the atomic nucleus with respect to the corresponding bombarding particle. Therefore, Professor Dempster's collaborators, physicists Ingram, Hess and Haydn, tried to accurately determine the effective cross section for neutron capture by natural mercury isotopes. In March 1947, they were able to show that the isotopes with mass numbers 196 and 199 have the largest neutron capture cross section and therefore have the highest probability of becoming gold. As a "by-product" of their experimental research, they received... gold! Exactly 35 micrograms, obtained from 100 mg of mercury after irradiation with slow neutrons in a nuclear reactor. This amounts to a yield of 0.035%, however, if the found amount of gold is attributed only to mercury-196, then a solid yield of 24% will be obtained, since gold-197 is formed only from the mercury isotope with a mass number of 196.

(n, p)-reactions often occur with fast neutrons, and with slow neutrons - predominantly (n, ()-transformations. Gold, discovered by Dempster's employees, was formed as follows: Hg + n = Hg* + (Hg* + e[ -] = Au The unstable mercury-197 formed by the (n, ()-process turns into stable gold-197 as a result of K-capture (of an electron from the K-shell of its own atom).

Thus, Ingram, Hess and Haydn synthesized appreciable amounts of artificial gold in an atomic reactor! Despite this, their "synthesis of gold" did not alarm anyone, since only scientists who carefully followed the publications in the "Physical Review" learned about it. The report was brief and probably not interesting enough for many because of its vague title: "Neutron cross-sections for mercury isotopes". However, chance would have it that two years later, in 1949, an overly zealous journalist picked up this purely scientific report and, in a noisily market-oriented manner, proclaimed in the world press about the production of gold in an atomic reactor. Following this, in France there was a major confusion in the quotation of gold on the stock exchange. It seemed that events were developing exactly as Rudolf Daumann had imagined, who predicted the "end of gold" in his science fiction novel.

However, artificial gold obtained in a nuclear reactor was long in coming. It had no intention of flooding the markets of the world. By the way, Professor Dempster had no doubts about it. Gradually, the French capital market calmed down again. This is not the last merit of the French magazine "Atoms", which in the January issue of 1950 published an article: "La transmutation du mercure en or" (Transmutation of mercury into gold).

Although the magazine, in principle, recognized the possibility of obtaining gold from mercury by a nuclear reaction, however, he assured his readers of the following: the price of such an artificial precious metal would be many times higher than natural gold mined from the poorest gold ores! Dempster's employees could not deny themselves the pleasure of getting a certain amount of such artificial gold in the reactor. Since then, this tiny curiosity has graced the Chicago Museum of Science and Industry. This rarity - evidence of the art of "alchemists" in the atomic age - could be admired during the Geneva conference in August 1955.

From the point of view of nuclear physics, several transformations of atoms into gold are possible. We will finally reveal the secret of the philosopher's stone and tell you how to make gold. We emphasize here that the only possible way is the transformation of nuclei. All other recipes of classical alchemy that have come down to us are worth nothing, they only lead to deception.

The stable gold, Au, could be made by radioactive decay of certain isotopes of neighboring elements. The so-called nuclide map teaches us this, in which all known isotopes and possible directions of their decay are presented. So, gold-197 is formed from mercury-197, which emits beta rays, or from such mercury by K-capture. It would also be possible to obtain gold from thallium-201 if this isotope emitted alpha rays. However, this is not observed. How to get a mercury isotope with a mass number of 197, which is not found in nature? Purely theoretically, it can be obtained from thallium-197, and the latter from lead-197. Both nuclides spontaneously with the capture of an electron turn into mercury-197 and thallium-197, respectively. In practice, this would be the only, albeit only theoretical, possibility of making gold from lead. However, lead-197 is also just an artificial isotope, which must first be obtained by a nuclear reaction. It won't work with natural lead.

Isotopes of platinum Pt and mercury Hg are also obtained only by nuclear transformations. Really feasible are only reactions based on natural isotopes. Only Hg, Hg and Pt are suitable as starting materials for this. These isotopes could be bombarded with accelerated neutrons or alpha particles in order to arrive at the following reactions: Hg + n = Hg* + (Hg + n = Hg* + 2n Pt + He = Hg* + n it would be possible to obtain the desired isotope of platinum from Pt by (n, ()-transformation or from Hg by (n, ()-process. In this case, of course, we must not forget that natural gold and platinum consist of a mixture of isotopes, so that in each In this case, competing reactions must be taken into account. Pure gold will eventually have to be isolated from a mixture of various nuclides and unreacted isotopes. This process will be very costly. The conversion of platinum into gold will generally have to be abandoned for economic reasons: as is known, platinum is more expensive than gold.

Another option for the synthesis of gold is the direct nuclear transformation of natural isotopes, for example, according to the following equations: Hg + p \u003d Au + He Hg + d \u003d Au + He The ((, p) -process (mercury-198) , ((, p)-process (platinum-194) or (p, () or (d, n)-transformation (platinum-196).

The question is only whether it is practically possible, and if so, whether it is cost-effective at all for the reasons mentioned. Only long-term bombardment of mercury with neutrons, which are present in the reactor in sufficient concentration, would be economical. Other particles would have to be obtained or accelerated in a cyclotron - such a method, as is known, gives only tiny yields of substances.

If natural mercury is subjected to the action of a neutron flux in a reactor, then, in addition to stable gold, mainly radioactive is formed. This radioactive gold (with mass numbers 198, 199 and 200) has a very short lifespan and within a few days turns back into the original substances emitting beta radiation: Hg + n= Au* + p Au = Hg + e[-] (2.7 days) It is by no means possible to exclude the reverse transformation of radioactive gold into mercury, that is, to break this Circulus vitiosus: the laws of nature cannot be circumvented.

Under these conditions, the synthetic production of an expensive noble metal, platinum, seems less complicated than "alchemy". If it were possible to direct the neutron bombardment in the reactor in such a way that predominantly (n, ()-transformations occurred, then one could hope to obtain significant amounts of platinum from mercury: all common isotopes of mercury - Hg, Hg, Hg - are converted into stable isotopes of platinum - Pt, Pt and Pt Of course, the process of isolating synthetic platinum is also very complicated here.

Frederick Soddy back in 1913 proposed a way to obtain gold by nuclear transformation of thallium, mercury or lead. However, at that time, scientists knew nothing about the isotopic composition of these elements. If the process of splitting off alpha and beta particles proposed by Soddy could be carried out, one would have to proceed from the isotopes Tl, Hg, Pb. Of these, only the Hg isotope exists in nature, mixed with other isotopes of this element and chemically inseparable. Therefore, Soddy's recipe was not feasible.

What even an outstanding researcher of the atom fails, of course, the profane cannot accomplish. The writer Daumann, in his book The End of Gold, published in 1938, gave us a recipe for turning bismuth into gold: by splitting off two alpha particles from the bismuth nucleus using high-energy X-rays. Such a ((, 2()-reaction is not known to date.

In addition, the hypothetical transformation Bi + (= Au + 2 (cannot go on for another reason: there is no stable Bi isotope. Bismuth is a monoisotopic element! The only natural isotope of bismuth with a mass number of 209 can give, according to the principle of the Daumann reaction, only radioactive gold-201, which with a half-life of 26 minutes turns back into mercury. As you can see, the hero of Daumann's novel, the scientist Bargengrond, could not get gold! Now we know how to really get gold. Armed with knowledge of nuclear physics, let's risk a thought experiment: 50 kg of mercury will be converted in a nuclear reactor into full-weight gold - into gold-197. Real gold is obtained from mercury-196. Unfortunately, only 0.148% of this isotope is contained in mercury. Therefore, only 74 g of mercury-196 is present in 50 kg of mercury, and only this amount can we transmute into true gold.

At first, let's be optimistic and assume that these 74 g of mercury-196 can be converted into the same amount of gold-197 if mercury is bombarded with neutrons in a modern reactor with a capacity of 10 neutrons / (cm * s). Imagine 50 kg of mercury, that is, 3.7 liters, in the form of a ball placed in a reactor, then a flux of 1.16 * 10 neutrons will act on the surface of mercury, equal to 1157 cm3, every second. Of these, 0.148%, or 1.69 * 10 neutrons, act on 74 g of the 196 isotope.

Therefore, we have 1.69 * 10 neutrons per second at our disposal in order to convert mercury-196 atoms. How many atoms is that actually? One mole of an element, that is, 197 g of gold, 238 g of uranium, 4 g of helium, contains 6.022 * 10 atoms. We can get an approximate idea of ​​this gigantic number only on the basis of a visual comparison. For example, this: imagine that the entire population of the globe in 1990 - about 6 billion people - started counting this number of atoms. Everyone counts one atom per second.

In the first second, 6 * 10 atoms would be counted, in two seconds - 12 * 10 atoms, etc. How long would it take humanity in 1990 to count all the atoms in one mole? The answer is staggering: about 3,200,000 years! 74 g of mercury-196 contains 2.27 * 10 atoms. In a second with a given neutron flux, we can transmute 1.69 * 10 mercury atoms. How long will it take to convert all of the mercury-196? Here is the answer: it will take an intense bombardment of neutrons from a high-flux reactor for four and a half years! We must make these enormous expenditures in order to eventually obtain only 74 g of gold from 50 kg of mercury, and such synthetic gold must also be separated from the radioactive isotopes of gold, mercury, etc.

Yes, that's right, in the age of the atom you can make gold. However, the process is too expensive. Gold obtained artificially in a reactor is priceless. It would be easier to sell a mixture of its radioactive isotopes as "gold". Maybe science fiction writers will be tempted to make up stories involving this "cheap" gold? "Mare tingerem, si mercuris esset" (I would turn the sea into gold if it consisted of mercury). This boastful saying was attributed to the alchemist Raimundus Lullus. Let's assume that we have turned not the sea, but a large amount of mercury into 100 kg of gold in a nuclear reactor. Outwardly indistinguishable from natural, this radioactive gold lies in front of us in the form of shiny ingots. From the point of view of chemistry, this is also pure gold. Some Croesus buys these bars at what he thinks is a similar price. He does not suspect that in reality we are talking about a mixture of radioactive isotopes Au and Au, the half-life of which is from 65 to 75 hours. You can imagine this miser who saw his golden treasure literally slipping through his fingers. For every three days his property is reduced by half, and he is not able to prevent it; in a week from 100 kg of gold there will be only 20 kg, after ten half-lives (30 days) - practically nothing (theoretically, this is another 80 g). Only a large puddle of mercury remained in the treasury. The deceptive gold of the alchemists!

The content of the article

GOLD- an element of group IA of the periodic table. Due to its low chemical activity, it belongs to the so-called noble metals. In nature, it is represented by the only stable nuclide 197 Au. More than ten radioactive isotopes of gold have been artificially obtained, of which the longest-lived is 195 Au with a half-life of 183 days. Since ancient times, the brilliance of gold has been compared with the brilliance of the sun (in Latin - sol), hence the Russian "gold". The English and German word gold, the Dutch goud, the Swedish and Danish guld (hence, by the way, guilders) in European languages ​​are associated with the Indo-European root ghel and even with the Greek sun god Helios. The Latin name for gold, aurum, means "yellow" and is related to Aurora (morning dawn).

For alchemists, gold was considered the “king of metals”, its symbol was the radiant sun, and the symbol of silver was the moon (at the same time, the ratio of the price of gold and silver in ancient Egypt corresponded to the ratio of the solar year to the lunar month).

Gold in nature.

There is very little gold in the earth's crust: only 4.3 10 -7% by weight, i.e., on average, only 4 mg per ton rocks, this is one of the rarest elements: it is three times less than the rare metal palladium, 15 times less than silver, 300 times less than tungsten, 600 times less than uranium, 10 thousand times less than copper. If all the gold were evenly dispersed - as in sea water - its extraction would be impossible ( cm. HABER). However, gold can actively migrate, for example, with groundwater, in which oxygen is dissolved. As a result of various migration processes, gold is concentrated in deposits - in quartz gold-bearing veins, in gold-bearing sand.

Distinguish between ore and placer gold. Ore gold occurs in the form of small (from 0.0001 to 1 mm) gold grains interspersed in quartz, in this form it occurs in quartz rocks in the form of thin inclusions or thicker veins penetrating sulfide ores - sulfur pyrite FeS 2, copper pyrite CuFeS 2 , antimony shine Sb 2 S 3, etc. Another form of ore gold is its rather rare minerals, in which gold is found in the form of chemical compounds (most often with tellurium, with which it forms silvery-white crystals, sometimes with a yellow tint): calaverite AuTe 2, montbreuite Au 2 Te 3, mutmannite (Ag,Au)Te (brackets indicate that these elements may be contained in the mineral in different proportions), krennerite (Ag,Au)Te 2, sylvanite (Ag,Au) 2 Te4, montbreuite (Au,Sb) 2 Te 3 , petzite Ag 3 AuTe 2 , aurostibite AuSb 2 , aurantimonate AuSbO 3 , auricupride Cu 3 Au, nagiagite Pb 5 Au(Te,Sb) 4 S 5–8 , tetraauricupride AuCu, fischesserite Ag 3 AuSe 2 and others.

Part of the gold in the processes of geological changes was carried away from the places of primary occurrence and again deposited in the places of secondary occurrence, thus alluvial gold was formed - a product of the destruction of primary deposits that accumulated in river valleys. It occasionally finds large nuggets, sometimes of a bizarre shape. Some of these deposits were formed 20-30 thousand years ago. The richest deposit on Earth, which stretches along the Witwatersrand mountain range (translated from the Dutch as "The Edge of White Water") in South Africa, is very old - it is about 3 billion years old.

Native gold is not chemically pure gold, it always contains impurities, sometimes in significant quantities: silver (from 2 to 50%), copper (up to 20%), iron, mercury, platinum group metals, bismuth, lead, tellurium and other. A natural alloy of gold and silver, containing 15 - 30% silver and some copper, the ancient Greeks called electron (the Romans - electrum) for its yellow: in Greek elektor - a radiant luminary, the sun, hence the Greek. elektron - amber.

A relatively high concentration of gold is found in hot spring water. So, in New Zealand, gold deposits were found in the pipes of a power plant operating on hydrothermal waters. Migrating with soil water, gold also enters plants, some of them (horsetails, corn) are able to collect gold. Horsetail ash in gold-bearing areas can contain up to 0.065% precious metal. Some bacteria can also collect gold by precipitating it from dilute solutions.

physical properties.

Gold is one of the heaviest metals: its density is 19.3 g/cm3. Only osmium, iridium, platinum and rhenium are heavier than gold. At one of the exhibitions, a small polished gold cube measuring just over 5 cm was shown, and the announcement said that whoever could pick it up with two fingers of one hand could take it with him. The organizers did not risk anything: no strongman could lift a slippery ingot weighing several kilograms in this way. If a room with an area of ​​20 square meters and a height of 3 meters is densely filled with gold bars, their mass will be 1150 tons - the weight of a heavily loaded train.

“Pure gold reflects yellow light, and in the form of very thin sheets (sheet gold), into which it is able to be forged and stretched, a bluish color shines through. in green... When heated, even in the forges, gold gives off vapors, which is why the flame passing over it turns greenish ”(D.I. Mendeleev. Fundamentals of Chemistry).

Yellow color is chemically pure gold, but impurities can color it in other colors - from white to green. Red (red) color gives gold, for example, copper at a certain content in the alloy. So, in the encyclopedia published in 1905, edited by Yu.N. Yuzhakov, it is said: “Red gold is an alloy of gold and copper in a ratio of 9: 1, used for minting coins.” The dictionary of V.I.Dal says the same: “Red gold - with a copper alloy; white gold with silver alloy.

Gold is a relatively fusible metal, melts at 1064°C, boils at 2880°C, and ranks third in thermal and electrical conductivity (after silver and copper). The hardness of gold on a 10-point Mohs scale is only 2.5, pure gold is too soft and is not suitable for any products. For hardness, other metals are always added to it, for example, silver or copper ( cm. GOLD PRODUCTS).

Gold easily alloys with many metals that can enter the crystal structure of gold without breaking it, but simply replacing the gold atoms. In this case, solid solutions are formed. Natural solid solutions with gold can form silver, copper, platinum, palladium, rhodium, iridium, and a number of other metals whose atomic sizes are the same as those of gold (radius 0.14 nm) or differ very little from it. Solid natural Au–Ag solutions sometimes contain up to 10% mercury (for example, in the Zolotaya Gora deposit in the Urals). In the presence of iron impurities (some finds in Yakutia contain up to 4.45% Fe), the mineral becomes magnetic.

Chemical properties.

Over the past centuries, chemists (and before them alchemists) have done a huge number of different experiments with gold, and it turned out that gold is not at all as inert as non-specialists think it is. True, sulfur and oxygen (aggressive towards most metals, especially when heated), do not act on gold at any temperature. An exception is gold atoms on the surface. At 500–700°C, they form an extremely thin, but very stable oxide, which does not decompose for 12 hours when heated to 800°C. This may be Au 2 O 3 or AuO (OH). Such an oxide layer was found on the surface of grains of native gold.

Gold does not react with hydrogen, nitrogen, phosphorus, carbon either, while halogens react with gold when heated to form AuF 3 , AuCl 3 , AuBr 3 and AuI. It is especially easy, already at room temperature, it reacts with chlorine and bromine water. Only chemists meet these reagents. In everyday life, the danger for gold rings is iodine tincture - an aqueous-alcoholic solution of iodine and potassium iodide: 2Au + I 2 + 2KI ® 2K.

Alkalis and most mineral acids have no effect on gold. But a mixture of concentrated nitric and hydrochloric acids (“aqua regia”) easily dissolves gold: Au + HNO 3 + 4HCl ® H + NO + 2H 2 O. After careful evaporation of the solution, yellow crystals of the complex hydrochloric acid HAuCl 4 3H 2 O stand out. Royal Vodka capable of dissolving gold was also known to the Arab alchemist Geber, who lived in the 9th-10th centuries. It is less known that gold dissolves in hot concentrated selenic acid: 2Au + 6H 2 SeO4 ® Au 2 (SeO4) 3 + 3H 2 SeO 3 + 3H 2 O. In concentrated sulfuric acid, gold dissolves in the presence of oxidizing agents: iodic acid, nitric acid, manganese dioxide. In aqueous solutions of cyanides, with the access of oxygen, gold dissolves with the formation of very strong dicyanoaurates: 4Au + 8NaCN + 2H 2 O + O 2 ® 4Na + 4NaOH; this reaction is the basis of an important industrial process for extracting gold from ores. They act on gold and melts from a mixture of alkalis and alkali metal nitrates: 2Au + 2NaOH + 3NaNO 3 ® 2Na + 2Na 2 O, sodium or barium peroxides: 2Au + 3BaO 2 ® Ba 2 + 3BaO, aqueous or ethereal solutions of higher chlorides of manganese, cobalt and nickel: 3Au + 3MnCl 4 ® 2AuCl 3 + 3MnCl 2, thionyl chloride: 2Au + 4SOCl 2 ® 2AuCl 3 + 2SO 2 + S 2 Cl 2, some other reagents. So, gold is far from being as “noble” as it is commonly believed.

The properties of finely divided gold are interesting. When gold is reduced from highly dilute solutions, it does not precipitate, but forms intensely colored colloidal solutions - hydrosols, which can be purple-red, blue, violet, brown, and even black. So, when a reducing agent (for example, 0.005% solution of hydrochloric acid hydrazine) is added to a 0.0075% solution of H, a transparent blue gold sol is formed, and if a 0.005% solution of potassium carbonate is added to a 0.0025% solution of H , and then add a solution of tannin dropwise when heated, then a red transparent sol is formed. Thus, depending on the degree of dispersion, the color of gold changes from blue (coarsely dispersed sol) to red (finely dispersed sol). At a sol particle size of 40 nm, the maximum of its optical absorption falls at 510–520 nm (red solution), and as the particle size increases to 86 nm, the maximum shifts to 620–630 nm (blue solution). The reduction reaction with the formation of colloidal particles is used in analytical chemistry to detect small amounts of gold.

When solutions of gold compounds are reduced with tin(II) chloride in slightly acidic solutions, an intensely colored dark purple solution of the so-called Cassian golden purple is formed (it is named after Andreas Cassius, a glassmaker from Hamburg who lived in the 17th century). This is a very sensitive reaction. When the gold sol loses its stability (coagulates), a black precipitate is formed, because. that it is precisely this color that the powder of any metal in a finely dispersed state has. Cassian purple, introduced into the molten glass mass, gives a magnificently colored ruby ​​​​glass, the amount of gold expended is negligible. Cassian purple is also used for painting on glass and porcelain, giving various shades when ignited - from slightly pink to bright red.

Organic compounds of gold are also known. Thus, by the action of gold(III) chloride on aromatic compounds, compounds are obtained that are resistant to water, oxygen and acids, for example: AuCl 3 + C 6 H 6 ® C 6 H 5 AuCl 2 + HCl. Organic derivatives of gold(I) are stable only in the presence of ligands coordinating with gold, for example, triethylphosphine: CH 3 Au·P(C 2 H 5) 3 .

Gold mining: technology.

As a result of natural concentration, approximately only 0.1% of all gold contained in the earth's crust is available, at least theoretically, for mining, however, due to the fact that gold occurs in its native form, shines brightly and is easily visible, it became the first metal with whom the person has met. But natural nuggets are rare, so the most ancient method of extracting a rare metal, based on the high density of gold, is washing gold sands. “Extraction ... of washing gold requires only mechanical means, and therefore it is no wonder that gold was known even to savages even in the most ancient historical times ”(D.I. Mendeleev. Fundamentals of Chemistry).

The “savages” shook the gold-bearing sand in a stream of water on an inclined tray, while the lighter sand was washed away, and the golden grains remained on the tray. This method was used by prospectors in modern times. Gold is almost 20 times heavier than water and about 8 times heavier than sand, so gold grains can be separated from sand or crushed waste rock with a jet of water. The ancient method of washing with the help of mutton skins, on which golden grains were deposited, is reflected in the ancient Greek myth of the Golden Fleece. Nuggets and placers of gold were often found along the course of rivers, which eroded gold-bearing rocks for thousands of years. In ancient times, gold was mined only from placers, and now, where they remain, gold-bearing sand is scooped out from the bottom of rivers and lakes and enriched on dredges - huge structures the size of a multi-storey building, capable of processing millions of tons of gold-bearing rock per year. But there were almost no rich gold placers left, and already at the beginning of the 20th century. 90% of all gold was mined from ores. Now many gold placers are practically exhausted, therefore, mostly ore gold is mined, however, now the extraction of ore gold is largely mechanized, but remains a difficult production, often hidden deep underground. In recent decades, the share of more cost-effective open-source developments has steadily increased. It is economically profitable to develop a deposit if a ton of ore contains only 2–3 g of gold, and if the content is more than 10 g/t, it is considered rich. Significantly, the cost of prospecting and exploration of new gold deposits ranges from 50 to 80% of all exploration costs.

The old (so-called mercury) method of extracting gold from ore - amalgamation is based on the fact that mercury well wets (but practically does not dissolve) gold - just like water wets (but does not dissolve) glass. Finely ground gold-bearing rock was shaken in barrels, at the bottom of which there was mercury. At the same time, gold particles stuck to the liquid metal, being wetted by mercury from all sides. Since the color of the gold particles disappears, it may appear that the gold has "dissolved". The mercury was then separated from the waste rock and heated strongly. The volatile mercury was distilled off, while the gold remained unchanged. The disadvantages of this method are the high toxicity of mercury and the incompleteness of gold extraction: its smallest particles are poorly wetted by mercury.

In the novel by A.N. Tolstoy Hyperboloid engineer Garin the hero hopes to get rich by finding in the depths of the globe a "golden layer" of liquid "mercury gold" containing "ninety percent pure gold." It was supposed to be "scooped directly from the surface" and pumped through pipelines to furnaces, where pure gold was to be obtained by evaporating mercury. In fact, the true solubility of gold in mercury is very low and is only 0.126% at 20 ° C. With prolonged exposure of gold in mercury, a chemical reaction occurs with the formation of solid at room temperature intermetallic compounds of the composition AuHg 2 , Au 2 Hg and Au 3 Hg, and at a high gold content, the formation of its solid solutions with mercury is also possible. Neither chemical compounds, nor solid solutions of gold and mercury can be "scooped from the surface" or passed through the "mercury conduit", as Garin intended to do.

More modern way extraction of gold from poor ores - leaching with sodium cyanide, in which even the smallest grains are converted into water-soluble cyanide compounds. Then, gold is extracted from the aqueous solution, for example, by extracting it with zinc powder: 2Na + Zn ® Na + 2Au. Leaching allows you to extract the remains of gold from the dumps of abandoned mines, actually turning them into a new deposit. The method of underground leaching is also promising: a cyanide solution is pumped into wells, it penetrates through cracks into the rock, where it dissolves gold, after which the solution is pumped out through other wells. Of course, cyanide will bring into solution not only gold, but also other metals that form stable cyanide complexes.

Another, rather poor, but constant source of gold is the intermediate products of lead-zinc, copper, uranium and some other industries. It is based on the fact that gold often coexists with other metals. Polymetallic ores often contain gold in the form of a small impurity, and they try to process their processing in such a way as to extract gold along the way, if this turns out to be profitable. So, during the electrolytic purification (refining) of copper, when it is “distilled” from the anode to the cathode, noble metals do not go into solution when the anode is dissolved, but accumulate under the anode in the form of sludge (sludge). This sludge is an important source of gold, which is mined the more, the larger the production of base metals. For example, in the USA it is one of the main sources of gold.

The so-called recycled gold is obtained from a huge mass of used or defective electronics products. They are thrown into molten copper directly in unpacked boxes; the wood instantly burns out, aluminum, iron, tin, and other base metals turn into oxides, float to the surface of the melt and are removed, and copper, after sufficient enrichment with noble metals, is sent for refining. An important source of secondary gold (up to 500 tons) per year is gold scrap.

And only of theoretical interest are nuclear reactions, with the help of which "alchemical gold" can be obtained from base metals. An example is the hypothetical reaction 209 Bi + 32 S ® 197 Au + 44 Ca, as well as the observed reaction of the capture of one “own” electron from the K-shell (K-capture) by an atom of one of the radioactive isotopes of mercury: 197 Hg + e ® 197 Au .

Gold mining: world production.

The oldest gold mines known to historians were in Egypt. There is evidence of gold mining and the manufacture of various products from it as early as the fifth millennium BC. - in the Stone Age. Rocks with gold-bearing quartz veins were heated in fire and then poured over with cold water. The cracked rock was crushed - crushed, crushed in mortars, ground and washed. The ancient Egyptians mined gold in the Arabian-Nubian gold-bearing province, located between the Nile and the Red Sea. For many centuries, during the reign of 30 dynasties, she gave it a huge amount - about 3500 tons. So, only under the pharaoh, the annual production reached 50 tons. At one time, less labor was expended there to extract gold than for other metals, and gold was cheaper than silver, but already in antiquity this richest deposit was completely depleted. In total, by the time of the capture by Rome in 30, the Egyptians had mined about 6,000 tons of gold. The huge gold riches that were in the burials of the pharaohs were almost all plundered in antiquity.

In ancient times, only gold-bearing rocks In Spain, the ancient Romans mined over 1,500 tons of gold. And in the middle of the 19th century. the mines of Austria-Hungary produced up to 6.5 tons of gold per year, on some gold coins of that time there are inscriptions in Latin “From the gold of the Danube”, “From the gold of the Isar”, “From the gold of the Inn” (tributaries of the Danube), “From the gold of the Rhine ". Mining in Finland was estimated at tens of kilograms per year. Now gold placers in the valleys of European rivers are almost completely exhausted. After the voyages of Columbus, Colombia, named after him, for a long time occupied a leading place in the world in gold mining. Very rich gold-bearing placers were found in the 18th–19th centuries. in Brazil, USA, Australia, other countries.

In Russia, there was no gold for a long time. The opinions of researchers differ about the beginning of its extraction. Apparently, the first domestic gold was mined in 1704 from the Nerchinsk ores along with silver. In subsequent decades, at the Moscow Mint, gold was isolated from silver, which contained some gold as an impurity (about 0.4%). So, in 1743–1744, “from gold found in silver smelted at the Nerchinsk factories”, 2820 chervonets were made with the image of Elizabeth Petrovna. The amount of gold mined was negligible: from 1719 to 1799, only 830 kg of gold was obtained in this way with great difficulty in chemical separation. According to some reports, small amounts of gold (in 1745 - 6 kg) were smelted, and secretly, at their Altai copper mines by the famous Demidovs. From 1746 all these mines became the property of the royal family.

In 1745, native ore gold was found in the Urals, and in 1747 the first domestic gold mine began to operate, later called Initial. Throughout the 18th century in Russia, only about 5 tons of gold were mined, but already in the next century - 400 times more. The discovery (in the 1840s) of the Yenisei deposit brought Russia to the first place in the world in gold mining in those years, but even before that, local Evenk hunters made bullets for hunting from gold nuggets. At the end of the 19th century Russia mined about 40 tons of gold per year, of which 93% was alluvial. In total, in Russia until 1917, according to official data, 2754 tons of gold were mined, but according to experts - about 3000 tons, and the maximum fell on 1913 (49 tons), when the gold reserve reached 1684.

Wars and revolution led to a sharp decline in gold production. So, in 1917, 28 tons were still mined, and three years later - only 2.5 tons, and the gold reserve also sharply decreased - to 317 tons (300 tons were taken to Germany under the terms of the Brest Peace, hundreds of tons left with the White Army through the Far East). The situation improved significantly by the end of the 1920s, after the discovery in Eastern Siberia of huge gold reserves in the Aldan River basin in Yakutia and Kolyma. In 1928, gold production already reached 28 tons and continued to grow steadily, reaching 302 tons in 1990. After the collapse of the USSR, Russia lost Central Asian gold, including the largest deposit in Uzbekistan (it consistently produced about 60 tons of gold per year). In 1991, only 168.1 tons of gold were mined in Russia, and production continued to decline from year to year, reaching a minimum in 1998 - 114.6 tons. After that, it began to grow at a rather rapid pace: 1999 - 126.1 tons, 2000 - 142.7 tons, 2001 - 154.5 tons, 2002 - 173.5 tons, 2003 - 176.9 tons. jewelry). We mine gold in the Magadan, Chita, Amur regions, in the Krasnoyarsk Territory, in Yakutia, in Chukotka.

Now the largest supplier of gold to the world market is South Africa, where the mines have already reached a depth of 4 km. South Africa is home to the world's largest Waal Reefs mine at Kleksdorp. When processing 10 million tons of ore, approximately 80–90 tons of gold are extracted there. In total, hundreds of tons of gold are mined in South Africa a year - about two tons daily. The total gold reserves in South Africa are estimated at 25,000 tons. South Africa is the only state in which gold is the main product of production, where gold is mined in 36 large mines that employ hundreds of thousands of people.

However, gold, unlike oil, is not consumed, but continuously accumulated, although not so rapidly in recent decades (world production peaked in 1972). On the other hand, its explored reserves are limited, and increasingly poorer deposits are being developed over time. All this cannot but be reflected (along with other factors) on the price of gold. The price, in turn, determines the profitability of production. Falling gold prices in the last two decades of the 20th century. dangerously brought the selling price closer to the cost of production, which was by the end of the 20th century. about $220 per troy ounce (31.1035 g) in the US and $260 in South Africa (even higher in some companies). This led to the collapse of some gold mining companies and a decrease in production by others. So, if in 1970 in South Africa 1004 tons of gold were mined (peak production), then in 1975 - 713 tons, in 1980 - 695 tons, in 1985 - 673 tons, in 2001 - only 399. And in Canada and Australia during the period of low prices for gold, its production was even subsidized by the state. At the same time, with a significant increase in the price of gold, the development of some deposits becomes profitable. In a number of developing countries, the cost of production remained relatively low (in Papua New Guinea - $ 150 per ounce), which allowed them to increase production. Annual gold production (in tons) in different years looked like this:

How much gold has been mined in total? And how much is left? Accounting (often not entirely reliable, especially if gold is mined by prospectors) has been kept since the discovery of America at the end of the 15th century. After the voyages of Columbus, the Spanish conquerors for several decades brought gold to Europe in such quantities that it depreciated 5-6 times. In the 19th century the whole world was shocked by the "gold rushes" after the discovery of rich deposits in California (1848), Australia (1851), the Klondike and Yukon in Alaska (1896 - 1900). "On gold" grew Largest cities– San Francisco, Sydney, Johannesburg, and the richest deposit in the world in South Africa, discovered in 1886 and containing about 30 g / t of gold, did not cause an influx of lone prospectors due to the peculiarities of its geological structure: to extract gold from hard rocks there It was possible only with the help of special equipment and the hardest work of the disenfranchised Negro population (at the beginning of the 20th century, even several tens of thousands of Chinese workers were brought to the mines).

Today, most gold has been mined in South Africa - about 50 thousand tons, in Russia and the USSR - more than 14 thousand, in the USA - more than 10 thousand (of which only in California - 3500 tons), a little less in Canada and Australia. A lot of gold (the account goes to thousands of tons) was mined in Colombia, Zimbabwe, Ghana, Mexico, and Brazil. Next come the Philippines, Zaire and Peru. And in all these countries, there are less deposits left than have already been produced. However, not all countries provided official information. So, in the USSR, any information about gold was classified, and the available information is an estimate.

The general results of gold mining are as follows. For the first 4400 years - from 3900 BC. (pre-dynastic archaic Egypt) up to 500 (fall of the Roman Empire) - 10,000 tons. Over the next 1000 years (Middle Ages) - another 2500 tons. From the beginning of the 16th century. before the beginning of the 19th century. (340 years) - 4900 tons. The bulk was mined over the past 200 years, and in total - about 130 thousand tons, with about two-thirds - during the last century (of which half - in South Africa). However, these huge quantities are only hundredths of a percent of the volume of steel smelted in the world in just one year. Collected in one place, all this gold would form a cube with an edge equal to 19 m, that is, a five-story building high (whereas the ore and sand from which this gold was extracted would represent a mountain over 2.5 km high). At the same time, gold, which is now mined all over the world in one year, would fit in a medium-sized room (although no floor can withstand such a load). If it were possible to distribute the gold mined throughout the history of mankind equally among the inhabitants of the Earth, each would receive a little more than 20 g, but such an operation is impossible even theoretically: tens of thousands of tons are irretrievably lost as a result of abrasion, burial in treasures, went to the seabed . The available gold is distributed as follows: about 10% in industrial products, the rest - approximately equally between centralized reserves (mainly in the form of standard ingots of chemically pure gold), private individuals and jewelry.

Gold mining: gold nuggets.

Along with small grains, large pieces of gold are occasionally found in gold-bearing regions - nuggets, which always attract the attention of not only miners. Newspapers write about large nuggets, news agencies around the world report. The Ural deposits were once very rich in nuggets. To date, approximately 10,000 nuggets weighing more than 10 kg have been found all over the world, and of these, about 2,000 are found only in the Miass district of Chelyabinsk. The largest is the “Big Triangle” measuring 39 × 33 × 25.4 cm and weighing 36 kg 7 g - was found in 1842 in the Southern Urals (Tsarevo-Aleksandrovsky mine), now it is stored in the Diamond Fund. Half a century later, a nugget weighing 20 kg was found in the Urals. Such nuggets are of considerable interest to scientists. Particularly rare are well-cut crystals of natural gold - sparkling octahedrons, cubes, rhombododecahedrons and their combinations. Sometimes native gold forms beautifully branching branches - dendrites.

At the beginning of the 19th century a decree was issued according to which all more or less large nuggets (weighing more than 10–20 g) were to enter the museum of the St. Petersburg Higher Mining School, but such a stream of gold poured from the Urals that in 1825 the minimum weight was increased to 409 g lb). But even such large nuggets accumulated so much that an order was received to hand over most of them (over a quarter of a ton) to the mint. The surviving nuggets, including the Big Triangle, formed the basis of the Diamond Fund. Now even not very large nuggets are unlikely to be melted down, because they are of collectible value and cost much more than the gold they contain.

Large nuggets (usually each of them has its own name) were found in Russia not only in the Urals. At the end of the 19th century in the Irkutsk region, a nugget weighing 22.6 kg was found, and in the middle of the 20th century. at the mines near the settlements of Bodaibo and Artemovsky, several dozen large nuggets weighing up to 10 kg or more were found. Kolyma turned out to be very rich in nuggets, where there are many mines. Already in the second half of the 20th century. there were found two nuggets weighing 14 kg and hundreds of smaller ones. They found and continue to find large nuggets also in Yakutia, in the Khabarovsk Territory, in Altai.

Among foreign countries, Australia became famous for large nuggets, where in the middle of the 19th century. found several nuggets weighing 50 kg or more. One of them, weighing 70.9 kg (69.2 kg of pure gold), was literally lying on the road: in 1869, a carriage driving along a country road broke a wheel on it. In Australia, in 1872, the world's largest nugget was also found - the "Holterman Plate" measuring 140 × 66 × 10 cm and weighing 285.76 kg from gold, closely intergrown with quartz, but this unique specimen was lost to science: everything was smelted from it. gold, which turned out to be 93.3 kg. At the end of the 20th century very large nuggets were unexpectedly found in Brazil. And small nuggets are found there in total more than 10 tons per year.

About larger nuggets, only the reports of ancient authors have been preserved, which are difficult to verify. So, al Biruni in his Mineralogy mentions a 2.5-ton nugget allegedly found in Afghanistan. According to other sources, a nugget weighing about 960 kg was found in the territory of modern Czech Republic in 752.

Application of gold.

Now gold is primarily a currency metal that performs the function of a universal money equivalent ( cm. GOLD AND ECONOMY). A lot of gold ends up in bank vaults, even more is used to make jewelry: they consume more than 70% of ingot metal. The jewelry industry consumes more gold per year than it is mined: in the 1990s - 2300-2700 tons annually. At the same time, industrialized countries consume only a third of gold, and developing countries - 60%. The largest consumer of gold is the population of India: in 2000, Indians bought 1,855 tons of the precious metal. Of course, one should also take into account the huge population of this country. Then come the USA (400–450 tons per year), Saudi Arabia(190–220 tons), China and Türkiye (about 200 tons); more than 100 tons per year are consumed by the countries of the Persian Gulf, South Korea, Egypt, Pakistan, Indonesia.

Gold is also spent on the manufacture of coins and medals, dentures, corrosion-resistant parts of chemical apparatuses, non-oxidizing electrical contacts, thermocouples, for the application of protective coatings, and the manufacture of special types of glass. Gold is used in the manufacture of parts for jet engines, rockets, nuclear reactors, heat and reflective coatings of spacecraft. As a catalyst, gold (in the form of a contact mesh) is used to oxidize hydrocyanic acid to cyanic acid, from which polymers and other products are obtained. Zinc sulfide, activated with gold, glows green under the influence of an electron beam, which is used in the manufacture of cathodoluminophores.

Gold is also used in medicine. In 1583, the French alchemist, court physician and surgeon David de Plany-Campi published A treatise on the true, unsurpassed, great and universal medicine of the ancients, or on drinking gold, an incomparable treasury of inexhaustible riches. In it, referring to his predecessors, mainly Arab alchemists, he described the healing properties of the so-called drinking gold, attributing to it the most miraculous properties. He relied on aurum potabile (drinking gold) and the famous alchemist of the 16th century. Philip Aureol Theophrastus Bombast von Hohenheim, better known as Paracelsus. This was gold in the literal sense of the word, only very finely crushed - a colloidal solution of red gold. Drinking gold is also mentioned in Chinese books on medicine dating back to the 1st century BC. BC. Chinese doctors meant by this name the "elixir of life" - a drink that gives youth, health and strength. It has now been established that gold, like silver, has bactericidal properties.

At the end of the 19th century German microbiologist Robert Koch discovered that potassium tetracyanoaurate(III) K stops the growth of tuberculosis bacteria. In the 20th century, gold preparations, for example, the thiosulfate complex sanokrisin Na 3 2H 2 O, began to be used to treat tuberculosis, arthritis, and as an anti-inflammatory agent. Now for the treatment of rheumatoid arthritis, the drug krizanol is used, containing 33.5% of gold in the form of calcium aurothiopropanolsulfonate (AuSCH 2 CH (OH) CH 2 SO 3) 2 Ca, and auranofin, also containing the Au–S bond and triethylphosphine coordinating with the gold atom :

R–S–Au ¬ P(C 2 H 5) 3 , where R is a fully acetylated glucose residue. It is assumed that gold preparations affect the immune processes in the body. Radiotherapy uses the 198Au radionuclide with a half-life of about 3 days.

The high density of gold sometimes leads to unusual applications. In the early 1990s, a popular science film about gold was filmed at the Tsentrnauchfilm film studio. Script writer and cameraman Evgeny Georgievich Pokrovsky, in search of interesting stories, visited the Diamond Fund in the Moscow Kremlin, where his attention was attracted by a gold ball in the window. An employee of the fund said that this ball weighs two pounds and was made by order of D.I. Mendeleev. However, for what purpose the ball was made, he could not say. The cameraman had to turn to a consultant for help.

It turned out that the Regulations of the State Council of the Russian Empire on June 8, 1863 in St. Petersburg established the Depot of Exemplary Weights and Measures. In 1892, Minister of Finance S.Yu. Witte suggested that D.I. Mendeleev take the post of scientific custodian of weights and measures at the Depot. Mendeleev accepted the offer and vigorously took up a new business for him. Soon the Depot was transformed into the Main Chamber of Weights and Measures; Mendeleev remained its manager for the last 15 years of his life. Over the years, he has carried out important research in the field of metrology - a branch of physics whose task is to create standards of physical units and develop methods for accurate measurements. Under the leadership of Mendeleev, Russian standards of the meter, liter, kilogram, as well as old measures - the pound, arshin, etc. were made. Mendeleev's goal was to switch the country to the metric system of measures, which was carried out only in 1918.

To conduct accurate measurements of the acceleration of free fall at the latitude of St. Petersburg in the Chamber, it was necessary to measure the period of oscillation of a pendulum of known length with high accuracy, since the length of the pendulum, the period of its oscillation and the acceleration of gravity are related by a simple relationship. But exactly it is carried out only for an ideal (mathematical) pendulum, in which the swing is small, the thread is weightless, the load is point, and there is no air resistance. In order for a real pendulum to be close to ideal, it must be made of heavy material and suspended from a long thin thread. So Mendeleev decided to use heavy gold as a weight for the pendulum. By his order, a massive polished (to reduce air resistance) golden ball was made. With a mass of 2 pounds (32 kg), its radius was only 7.3 cm. Since there were no high halls in the building of the Chamber, Mendeleev, in order to lengthen the suspension thread, ordered to break through the floors on several floors, and even dig a hole in the basement. With the help of such a pendulum, it was possible to measure the acceleration of gravity with high accuracy.

Ilya Leenson

Literature:

Sobolevsky V. noble metals. Gold. M., Knowledge, 1970
Busev A.I., Ivanov V.M. Analytical chemistry of gold. M., Science, 1973
Maksimov M.M. essay on gold. M., Nedra, 1977
Malyshev V.M. Gold. M., Metallurgy, 1979
Paddefet R. Chemistry of gold. M., Mir, 1982
Potemkin S.V. Noble 79th. M., Nedra, 1988

The outstanding physicist Isaac Newton, in addition to his work in the field of theoretical physics, was engaged in alchemy for several decades. Moreover, he was completely confident in its capabilities and therefore, with another physicist Robert Boyle, he introduced an interesting bill to the British Parliament. It spoke about the prohibition of disclosing the transformation of metals, for example, how to make gold from lead, because this could lead to a fall in the price of gold.

Philosopher's Stone and other experiments of alchemists

At the beginning of the last century, papyrus was found in the tomb of the city of Thebes. It contained 111 recipes, among which were methods for obtaining gold and silver. However, most of these recipes still referred to methods for creating fakes or coating other metal with them. Nevertheless, such a document shows how already then alchemy was widespread and captured the minds of those who were thirsty for easy money.

Isaac Newton

Descended from the Greeks and Egyptians, it gradually captured the whole of Europe. In the Middle Ages, not only some scientists were engaged in alchemy, but also persons of the highest state and church ranks. Almost every imperial court had its own alchemists, intending to get gold, which would improve the state of the treasury. To get gold, in their opinion, perhaps, you just need to somehow find or create a philosopher's stone.

The records of the alchemists of that time were vague and difficult to understand. Here, for example, Lull's recipe for obtaining such a stone.

It was proposed to take the mercury of philosophers and burn it until a green lion is obtained, and then a red one. It already had to be heated in a sand bath along with the acidic spirit of the grapes. The gum obtained from evaporation had to be distilled using a distillation projectile. After that, a true dragon will remain in the distillation projectile itself, which will be rubbed on a stone and touched with hot coal. After that, overtake again, as a result, burning water and blood are obtained - this is the elixir.

Later, this recipe was deciphered. It turned out that mercury is lead, the green lion is its oxide, the red one is minium, and the black dragon is lead powder with coal. The result was the usual chemical reaction - the distillation of acetic lead salt. Thus, products were obtained that are capable of recovering gold from solutions of its salts.

Alchemy flourished in the middle of the 17th century. Then it was difficult to say what substance the alchemists were dealing with, and such hobbies were supported by high-ranking officials, which stimulated development. Many kings and emperors were themselves alchemists and, by the way, many of the transformations they carried out are not entirely a hoax. Simply, most likely, the original substance already contained gold in one form or another.

Over time, the number of people who believed in alchemy became less and less. This was due to the fact that the alchemists declared the philosopher's stone a remedy for all diseases. And when this was not justified in practice, people began to doubt alchemy.

However, some transformations of metals could not be explained then. The experiences of many eventually gave gold. This was due to the fact that some of the natural ores contain some amount of gold initially. And through various chemical reactions, it was possible to purify it.

In 1709, the famous alchemist Gobmerg obtained gold by melting silver with antimony ore. The output turned out to be quite a bit of gold, but he was sure that he had found the secret of the transformation of metals. Over time, when they were able to conduct an accurate analysis of the ore, it turned out that a certain percentage of gold was contained there from the very beginning.

In 1783, the pharmacist Kappel was able to turn silver into gold with the help of arsenic. The secret of his experience turned out to be similar: gold was contained in arsenic ore.

Nuclear transformations.

After the discovery of the atom and the reactions for its transformation, nuclear physicists took up the production of gold. And in 1935, the physicist Dempster studied the mass spectrographic data of gold and came to the conclusion that there is only one stable isotope of this metal, with a mass number of 197. This meant that one had to look for such a nuclear reaction that would give exactly this isotope.

In 1940, many laboratories began to study this issue in more detail. They carried out experiments on the bombardment by fast neutrons of elements adjacent to gold in the periodic table, platinum and mercury. A year later, American physicists Sherr and Bainbridge reported successful results: by bombarding mercury atoms with fast neutrons, they obtained gold.

But the isotopes had mass numbers of 198, 199, and 200. So they didn't quite make it, they got gold, but it existed for a short amount of time. Consequently, modern adherents of alchemy had no reason to rejoice, and experiments had to be continued.

From the experiments of Scherr and Bainbridge, they concluded that gold isotopes were obtained from mercury atoms with the corresponding atomic numbers. And this assumption seemed justified. The probability of a nuclear reaction occurring is determined by the effective cross section for capturing the nucleus with respect to the particle that bombards it.

Thus, it was shown that mercury atoms with mass numbers 196 and 199 have the most chances to turn into gold. And after the reaction, they really got it. 100 grams of mercury turned into 35 micrograms of gold. In 1950, the French magazine "Atoms" wrote that the price of such gold turned out to be much higher than the market price due to the high cost of nuclear transformations. Therefore, it did not gain popularity.

Obtaining gold-197 (its stable isotope) could theoretically be carried out by transformations of certain isotopes of neighboring elements. According to the map of nuclides, gold-197 can be obtained from mercury with the same mass number. It could also be obtained from thallium-201 if this element had alpha decay, which it does not.

What remains is the mercury-197 isotope, which does not exist in nature. It could be obtained from thallium-197 or lead-197. This would be the only possible conversion reaction to lead. But here comes a new snag. The fact is that there is no such isotope, it must first also be created by nuclear transformations.

Thus, purely theoretically, it is possible to obtain gold from lead. And in practice, it can be obtained by the transformation of mercury. But such a process is too expensive, which makes the resulting metal "priceless".