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.
How much less? I believe most gold produced in the US is from ore with under a half ppm gold (E.g open pit mines in Nevada).
Maybe the point there is that we already have practically endless supplies of quarter ppm ore ready for the taking on the surface of the earth. Gold is rare only in so far that the current price reflects the breakeven point of these most abundant sources. Adding more supply with similar or worst production costs wouldn't change anything.
All the other precious metals are less than 1 ppm compared to iron, but platinum is more abundant, and by weight it is about 6 ppm in iron.
The advantage of an asteroid is that its entire metal core has 6 ppm of platinum and a fraction of a ppm of gold, while on Earth the quantities of ore containing such amounts of precious metals like a half ppm or a quarter ppm of gold are much smaller.
There certainly exists no "endless supply" of gold ore with a quarter ppm gold, because the average concentration of gold in the crust of the Earth is a few parts per billion, so the few places where the concentration is as high as a fraction of a ppm are compensated by vast areas where the gold concentration is much less than one part per billion.
While an asteroid may have a lot of iron containing 6 ppm of platinum and a little less than 1 ppm of gold, that is not comparable at all with a terrestrial ore with 1 ppm or a few ppm of precious metals.
The precious metals are the easiest to separate from rocks, which is why one can exploit on Earth ores with a so low content of metal. On the other hand, precious metals are very hard to separate from iron, which is the very reason why in any planet or asteroid these metals end up being dissolved in the iron core.
So the extraction of platinum or gold in so small quantities from iron would be extremely expensive on Earth and much more so on an asteroid, where it is impossible to produce most of the chemicals used on Earth, like acids or cyanides.
Those are the average abundances in the iron that forms the asteroid metallic cores, which are exposed in a few asteroids, presumably because of ancient collisions.
The asteroids where such cores are exposed, instead of being buried under huge amounts of rocks, like in the planets, are those that are targeted for mining.
The iron meteorites are pieces detached from such asteroid cores, so they provide samples of their composition.
Some meteorites, the so-called chondrites, come from small bodies that have never aggregated into bigger asteroids or planets since the formation of the Solar System, so they have a chemical composition close to the average composition of the Solar System.
Other meteorites have been detached from big bodies, like asteroids, planets (e.g. from Mars) or from the Moon.
These meteorites are either made of rocks, when they have been detached from the surface of such bodies, or made of an alloy of iron, nickel, cobalt, germanium, some times also silicon, together with other metals that are present in much smaller quantities, when they have been detached from exposed asteroid cores.
>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.
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.
39 comments
Why then gold in the title? Probably just because it's shiny.
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.
> in proportions of less than 1 part per million.
How much less? I believe most gold produced in the US is from ore with under a half ppm gold (E.g open pit mines in Nevada).
Maybe the point there is that we already have practically endless supplies of quarter ppm ore ready for the taking on the surface of the earth. Gold is rare only in so far that the current price reflects the breakeven point of these most abundant sources. Adding more supply with similar or worst production costs wouldn't change anything.
The advantage of an asteroid is that its entire metal core has 6 ppm of platinum and a fraction of a ppm of gold, while on Earth the quantities of ore containing such amounts of precious metals like a half ppm or a quarter ppm of gold are much smaller.
There certainly exists no "endless supply" of gold ore with a quarter ppm gold, because the average concentration of gold in the crust of the Earth is a few parts per billion, so the few places where the concentration is as high as a fraction of a ppm are compensated by vast areas where the gold concentration is much less than one part per billion.
While an asteroid may have a lot of iron containing 6 ppm of platinum and a little less than 1 ppm of gold, that is not comparable at all with a terrestrial ore with 1 ppm or a few ppm of precious metals.
The precious metals are the easiest to separate from rocks, which is why one can exploit on Earth ores with a so low content of metal. On the other hand, precious metals are very hard to separate from iron, which is the very reason why in any planet or asteroid these metals end up being dissolved in the iron core.
So the extraction of platinum or gold in so small quantities from iron would be extremely expensive on Earth and much more so on an asteroid, where it is impossible to produce most of the chemicals used on Earth, like acids or cyanides.
The asteroids where such cores are exposed, instead of being buried under huge amounts of rocks, like in the planets, are those that are targeted for mining.
The iron meteorites are pieces detached from such asteroid cores, so they provide samples of their composition.
Some meteorites, the so-called chondrites, come from small bodies that have never aggregated into bigger asteroids or planets since the formation of the Solar System, so they have a chemical composition close to the average composition of the Solar System.
Other meteorites have been detached from big bodies, like asteroids, planets (e.g. from Mars) or from the Moon.
These meteorites are either made of rocks, when they have been detached from the surface of such bodies, or made of an alloy of iron, nickel, cobalt, germanium, some times also silicon, together with other metals that are present in much smaller quantities, when they have been detached from exposed asteroid cores.
>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.
> melting one ton of iron requires 500KWh, 12 gallons of gasoline, less than $100 on Earth
The spot price for platinum today is $68, so you'd be losing money doing it.
> 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
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.