I'm confused. The article is about how various excited states of tin are generated. But tin is atomic number 50, platinum and gold are 78 and 79 respectively. Can someone draw a line between these?
It's about refining theoreticals models that are used to predict nucleosynthesis of heavier elements. The researchers used indium because we can obtain the required neutron-heavy isotopes for indium but not for heavier elements such as gold or platinum. But improving the model with data from indium, they say, makes it more accurate for gold as well?
Why then gold in the title? Probably just because it's shiny.
Platinum is also a peak of element abundance, together with its neighbor elements.
So any model of how the elements have been produced must explain why the probability of making platinum and its neighbor elements, osmium, iridium and gold was higher than the probability of making other elements.
The existence of other abundance peaks is easier to understand, e.g. the peaks at tin and at lead happened because these 2 metals have "magic" numbers of protons, i.e. 50 and 82, which correspond to complete nucleon layers.
The peak at platinum is higher to understand, so to explain it you need accurate models.
On Earth it is not obvious that the heavy platinum-group metals and gold are located on an abundance peak, because all these precious metals have gone deep inside the Earth, into its iron core, so the crust of the Earth is depleted in them, which has made them rare and precious.
There are asteroids where the iron cores are easily accessible and they contain great amounts of platinum and related metals. However, the idea that mining that would be easy is extremely naive.
On Earth, mining gold and platinum is easy, because they do not mix with silicate rocks so they can be found as native metals or sulfides/arsenides/tellurides that can be easily separated from silicate rocks and then the metals are easy to extract.
On the other hand, in asteroids platinum and the other precious metals are dissolved in iron uniformly, so they are extremely diluted, in proportions of less than 1 part per million. Therefore, even if the total amount of platinum and gold is huge, concentrating one gram of platinum from one ton of iron would be tremendously difficult, requiring a huge amount of energy.
Mining asteroids for the purpose of bringing something back to Earth will certainly not happen before solving much easier problems, e.g. growing back an amputated leg or any other part of the body. The fact that at least a startup exists that claims to work to achieve such mining is just a certain scam with no other goal than mine money from naive investors.
>concentrating one gram of platinum from one ton of iron would be tremendously difficult, requiring a huge amount of energy.
melting one ton of iron requires 500KWh, 12 gallons of gasoline, less than $100 on Earth. Or 5 Tesla car batteries fully charged by say 30x30 m solar array in 2.5 hours - cost nothing in space once you got the hardware there. This is why mining in space is going to be a pretty big thing once/if we get cheap launch capability.
Since you didn't show your math, I did a quick calculation. .45J/g/C specific heat of iron means .45MJ/tonne. 1811K to melt iron means 815MJ/tonne. 3.6kWh/MJ, so 226.4 kWh should melt 1t of iron.
Yes, but melting is just the beginning of the process. Even your computation is incomplete, because it is not enough to heat iron until the melting temperature, you must also provide the additional latent heat of melting. Similarly for boiling iron, after heating to the boiling temperature there is an additional latent heat of vaporization.
There is still no easy way to separate platinum-group metals from liquid iron, so you must vaporize the iron, to exploit the fact that platinum-group metals have higher boiling temperatures. It is true however that at the low pressures easily achievable in vacuum, vaporization is easier than on Earth.
Otherwise than by vaporization, you could dissolve iron with an acid, but on such asteroids you do not have with what to make an acid, so you would have to transport it from some other asteroid, or more likely from a satellite of Jupiter. You would also need a chemical plant to make the acid and also to recycle the iron salts into regenerated acid. This is so much more complicated, that vaporization of the iron might be simpler.
Finally, you must account for the fact that the energy required to vaporize one ton of iron produces less than a gram of platinum and of each other platinum-group metals. It is unlikely that you could build there a solar array big enough to provide energy for vaporizing a million of tons of iron, to make a ton of platinum, so you would need a nuclear reactor.
While platinum-group metals might be obtained as a minuscule residue after vaporizing the iron, gold has about the same vapor pressure as the much more abundant iron, nickel, cobalt and germanium, so it would be impossible to extract it from iron by vaporization. It could be extracted only with a chemical method, e.g. with an acid or with oxygen, which need to be brought from elsewhere.
Taking all these into account, it seems that there is no chance of being able to mine precious metals at a cost less than on Earth any time soon, e.g. in the current century. Extraordinary reductions in the cost of interplanetary transport would be needed and in the cost of building a metallurgic plant on an asteroid.
Mining asteroids would make sense only if some people would decide to live in huge space stations with artificial gravity, instead of on Earth, and then some asteroids would be mined for making steel and other construction materials, to be used in the interplanetary space, not on Earth.
True, but even with that, the amount of siderophile elements like platinum and gold in the crust is much less than in the core of the Earth ("siderophile" means that at the contact between molten iron and molten silicate rock such elements go into the molten iron).
Without that impact, it is assumed that almost no platinum-group metals and gold would have remained in the crust.
> Without that impact, it is assumed that almost no platinum-group metals and gold would have remained in the crust.
Wow, its wild to think of a counterfactual world without gold. Would those metals have emerged to the crust from volcanism or is that material not sourced deeply enough?
Tangentially related from something I'm currently reading¹:
> This is the reality of twenty-first-century resource exploitation: reducing vast quantities of rock into granules and chemically processing what remains. It is both awe inspiring and disturbing. One risk is that the cyanide and mercury used in the method could escape into the surrounding ecosystem. After all, while miners like Barrick insist they follow all the rules laid down by the US Environmental Protection Agency (EPA), campaigners warn that pollution often finds its way out of the mine. Indeed, a few years earlier the EPA had fined Barrick and another nearby miner $618,000 for failing to report the release of toxic chemicals including cyanide, lead and mercury. But the main thing I was struck by as I observed each stage in this process was just how far we will go these days to secure a tiny shred of shiny metal.
> The scale, for one thing, was mind-boggling. As I looked down into the pit I could just about make out some trucks on the bottom, but only when they emerged at the top did I realise that they were bigger than three-storey buildings; the tyres alone were the size of a double-decker bus. How much earth do you have to remove to produce a gold bar? I asked my minders. They didn’t know, but they did know that in a single working day those trucks would shift rocks equivalent to the weight of the Empire State Building.
¹ Material World: A Substantial Story of Our Past and Future by Ed Conway
does anyone else experience an “eyes glazing over” effect when you read things like “Heavy elements such as gold and platinum are forged under extraordinary conditions, including when stars collapse, explode, or collide”?
It seems totally beyond possible in scope and scale to validate something like this, even if you managed to get up close to one of these events it would still be too big and powerful to follow what is happening.
It is quite difficult to validate if you only consider the most direct of means like smashing two stars together and then physically going out and picking up the pieces.
There are other means to validate that type of thing though. Trying to come up with those means is a lot of fun. Can you think of any?
I'm confused. The article is about how various excited states of tin are generated. But tin is atomic number 50, platinum and gold are 78 and 79 respectively. Can someone draw a line between these?
It's about refining theoreticals models that are used to predict nucleosynthesis of heavier elements. The researchers used indium because we can obtain the required neutron-heavy isotopes for indium but not for heavier elements such as gold or platinum. But improving the model with data from indium, they say, makes it more accurate for gold as well?
Why then gold in the title? Probably just because it's shiny.
Platinum is also a peak of element abundance, together with its neighbor elements.
So any model of how the elements have been produced must explain why the probability of making platinum and its neighbor elements, osmium, iridium and gold was higher than the probability of making other elements.
The existence of other abundance peaks is easier to understand, e.g. the peaks at tin and at lead happened because these 2 metals have "magic" numbers of protons, i.e. 50 and 82, which correspond to complete nucleon layers.
The peak at platinum is higher to understand, so to explain it you need accurate models.
On Earth it is not obvious that the heavy platinum-group metals and gold are located on an abundance peak, because all these precious metals have gone deep inside the Earth, into its iron core, so the crust of the Earth is depleted in them, which has made them rare and precious.
There are asteroids where the iron cores are easily accessible and they contain great amounts of platinum and related metals. However, the idea that mining that would be easy is extremely naive.
On Earth, mining gold and platinum is easy, because they do not mix with silicate rocks so they can be found as native metals or sulfides/arsenides/tellurides that can be easily separated from silicate rocks and then the metals are easy to extract.
On the other hand, in asteroids platinum and the other precious metals are dissolved in iron uniformly, so they are extremely diluted, in proportions of less than 1 part per million. Therefore, even if the total amount of platinum and gold is huge, concentrating one gram of platinum from one ton of iron would be tremendously difficult, requiring a huge amount of energy.
Mining asteroids for the purpose of bringing something back to Earth will certainly not happen before solving much easier problems, e.g. growing back an amputated leg or any other part of the body. The fact that at least a startup exists that claims to work to achieve such mining is just a certain scam with no other goal than mine money from naive investors.
>concentrating one gram of platinum from one ton of iron would be tremendously difficult, requiring a huge amount of energy.
melting one ton of iron requires 500KWh, 12 gallons of gasoline, less than $100 on Earth. Or 5 Tesla car batteries fully charged by say 30x30 m solar array in 2.5 hours - cost nothing in space once you got the hardware there. This is why mining in space is going to be a pretty big thing once/if we get cheap launch capability.
Since you didn't show your math, I did a quick calculation. .45J/g/C specific heat of iron means .45MJ/tonne. 1811K to melt iron means 815MJ/tonne. 3.6kWh/MJ, so 226.4 kWh should melt 1t of iron.
Yes, but melting is just the beginning of the process. Even your computation is incomplete, because it is not enough to heat iron until the melting temperature, you must also provide the additional latent heat of melting. Similarly for boiling iron, after heating to the boiling temperature there is an additional latent heat of vaporization.
There is still no easy way to separate platinum-group metals from liquid iron, so you must vaporize the iron, to exploit the fact that platinum-group metals have higher boiling temperatures. It is true however that at the low pressures easily achievable in vacuum, vaporization is easier than on Earth.
Otherwise than by vaporization, you could dissolve iron with an acid, but on such asteroids you do not have with what to make an acid, so you would have to transport it from some other asteroid, or more likely from a satellite of Jupiter. You would also need a chemical plant to make the acid and also to recycle the iron salts into regenerated acid. This is so much more complicated, that vaporization of the iron might be simpler.
Finally, you must account for the fact that the energy required to vaporize one ton of iron produces less than a gram of platinum and of each other platinum-group metals. It is unlikely that you could build there a solar array big enough to provide energy for vaporizing a million of tons of iron, to make a ton of platinum, so you would need a nuclear reactor.
While platinum-group metals might be obtained as a minuscule residue after vaporizing the iron, gold has about the same vapor pressure as the much more abundant iron, nickel, cobalt and germanium, so it would be impossible to extract it from iron by vaporization. It could be extracted only with a chemical method, e.g. with an acid or with oxygen, which need to be brought from elsewhere.
Taking all these into account, it seems that there is no chance of being able to mine precious metals at a cost less than on Earth any time soon, e.g. in the current century. Extraordinary reductions in the cost of interplanetary transport would be needed and in the cost of building a metallurgic plant on an asteroid.
Mining asteroids would make sense only if some people would decide to live in huge space stations with artificial gravity, instead of on Earth, and then some asteroids would be mined for making steel and other construction materials, to be used in the interplanetary space, not on Earth.
I thought the impact of Thea made heavier elements spread much more evenly towards the surface.
True, but even with that, the amount of siderophile elements like platinum and gold in the crust is much less than in the core of the Earth ("siderophile" means that at the contact between molten iron and molten silicate rock such elements go into the molten iron).
Without that impact, it is assumed that almost no platinum-group metals and gold would have remained in the crust.
> Without that impact, it is assumed that almost no platinum-group metals and gold would have remained in the crust.
Wow, its wild to think of a counterfactual world without gold. Would those metals have emerged to the crust from volcanism or is that material not sourced deeply enough?
I am surprised that the s-process plays no role in the formation of gold.
Tangentially related from something I'm currently reading¹:
> This is the reality of twenty-first-century resource exploitation: reducing vast quantities of rock into granules and chemically processing what remains. It is both awe inspiring and disturbing. One risk is that the cyanide and mercury used in the method could escape into the surrounding ecosystem. After all, while miners like Barrick insist they follow all the rules laid down by the US Environmental Protection Agency (EPA), campaigners warn that pollution often finds its way out of the mine. Indeed, a few years earlier the EPA had fined Barrick and another nearby miner $618,000 for failing to report the release of toxic chemicals including cyanide, lead and mercury. But the main thing I was struck by as I observed each stage in this process was just how far we will go these days to secure a tiny shred of shiny metal.
> The scale, for one thing, was mind-boggling. As I looked down into the pit I could just about make out some trucks on the bottom, but only when they emerged at the top did I realise that they were bigger than three-storey buildings; the tyres alone were the size of a double-decker bus. How much earth do you have to remove to produce a gold bar? I asked my minders. They didn’t know, but they did know that in a single working day those trucks would shift rocks equivalent to the weight of the Empire State Building.
¹ Material World: A Substantial Story of Our Past and Future by Ed Conway
> in a single working day those trucks would shift rocks equivalent to the weight of the Empire State Building.
Oh. My. God.
does anyone else experience an “eyes glazing over” effect when you read things like “Heavy elements such as gold and platinum are forged under extraordinary conditions, including when stars collapse, explode, or collide”?
It seems totally beyond possible in scope and scale to validate something like this, even if you managed to get up close to one of these events it would still be too big and powerful to follow what is happening.
It is quite difficult to validate if you only consider the most direct of means like smashing two stars together and then physically going out and picking up the pieces.
There are other means to validate that type of thing though. Trying to come up with those means is a lot of fun. Can you think of any?
And they said turning Lead into Gold was just heresy.