Turn Mercury into Gold Cheaply?

Ziggurat said:
The biggest source of inefficiency is simply that most photons hitting a mercury atom aren't going to eject a neutron. Most of them will scatter off the electrons surrounding the nucleus.
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Could one send a monatomic stream of mercury through a terrifically powerful magnetic field--enough to distort the electron shell and gain some efficiency? Obviously one would have to be precise enough to aim the gamma rays at a tiny spot, and you wouldn't be able to move all of the electrons, no matter how powerful the field, but it might be enough for some kind of noticable improvement.

- Dr. Trintignant
 
jhunter1163 said:
If it was commercially viable, someone would be doing it already, no?
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Not necessarily. You might as well ask why some old gold mines are reopening--why wouldn't they be open already? And the simple answer is that a process can be commercially viable at one price but not another.

- Dr. Trintignant
 
There's a big, irreducible efficiency loss that no one has mentioned had mentioned by the time I clicked "reply". When you shoot a gamma ray beam at a target---any target---only a tiny fraction of them interact with the nuclei. Most interact with the electrons. I don't know the specific cross section for 198Hg(gamma,n), but typically photonuclear interactions in heavy nuclei will be < 1/1000 as likely as electron interactions. Maybe that goes up to 1/10 or 1/20 if you're exactly at the giant dipole resonance.

The efficiency of an accelerator, in turning wall-plug power into *electron beam* power, is in the ballpark of 1%. I'd guess that the efficiency of turning electron beam power into gamma-ray beam power is, for ~7 MeV gammas, something like 5-10%.

So you need to buy 6.8 MeV * 100 (accelerator) * 10 (gamma conversion) * 1000 (non-photonuclear loss of gammas) = 6.8 TeV worth of energy in order to make one gold nucleus.

Forget it.

Here's the other thing. You're making gold out of 198Hg, not natural mercury; it's only 10% of natural mercury. So you ran your 198Hg through an isotope separation plant, and isotope separation is expensive. Physics experiments sometimes use large quantities of unusual isotopes; separation typically costs $80,000/kg---more than gold costs to begin with!

If you had a source of free gamma rays, you'd be better off buying gold---which is all 197Au to begin with---and transmuting it into 196-Pt.
 
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Dr. Trintignant said:
Could one send a monatomic stream of mercury through a terrifically powerful magnetic field--enough to distort the electron shell and gain some efficiency?
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No. You can distort the shell all you want to, but since this is scattering from the bound state to the free state (not between bound states), as long as the electrons are there, they'll still scatter more strongly than the nucleus. The only way to significantly lower the electron scattering cross section I can imagine would be if you actually started stripping electrons off the mercury atoms. But that would require enormous energy to achieve as well, and might not raise the efficiency enough to compensate. It could even make it worse, since you can't have very dense ionized mercury, so you might just end up with a lot of your photons simply passing through the mercury completely (whereas with an unionized mass, you can simply make the target thick enough to absorb basically all the radiation).
 
Dr. Trintignant said:
Could one send a monatomic stream of mercury through a terrifically powerful magnetic field--enough to distort the electron shell and gain some efficiency? Obviously one would have to be precise enough to aim the gamma rays at a tiny spot, and you wouldn't be able to move all of the electrons, no matter how powerful the field, but it might be enough for some kind of noticable improvement.

- Dr. Trintignant
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Nope. The effect will be miniscule.
 
ben m said:
There's a big, irreducible efficiency loss that no one has mentioned. When you shoot a gamma ray beam at a target---any target---only a tiny fraction of them interact with the nuclei. Most interact with the electrons.
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What do you mean, nobody mentioned that yet? I mentioned that several posts ago. You're late to the party.

But that's useful details on particle accelerator efficiency.
 
Just need a cheap source of N16 gammas...

IIRC, there aren't any naturally occuring gamma sources above about 2.5 MeV.

glenn
 
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Dr. Trintignant said:
Copper is a better electrical conductor than gold (by a perhaps surprising margin).
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Hmmm... I guess they're farther apart than I though. 1.68x10-8 ohm-meters for copper vs. 2.44x10-8 for gold.

The corrosion resistance of gold obviously has some uses, though.
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It would make great cookware. :D
 
Skeptical Greg said:
Did a lot of alchemists die from mercury and lead poisoning ?
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Mercury more than lead.

Almost certainly Isaac Newton poisoned himself. A neurologist named Klawans wrote a book called "Newton's Madness", and makes the case pretty well. It's entertaining and informative, and I recommend it.
 
Likewise from same wikipedia source:

"Using fast neutrons, the mercury isotope 198Hg, which composes 9.97% of natural mercury, can be converted by splitting off a neutron and becoming 197Hg, which then disintegrates to stable gold. This reaction, however, possesses a smaller activation cross-section and is feasible only with un-moderated reactors."

and

"Only the mercury isotope 196Hg, which occurs with a frequency of 0.15% in natural mercury, can be converted to gold by neutron capture, and following electron capture-decay into 197Au with slow neutrons."

This too still way to expensive?
 
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7up said:
Gold obtained by mining has copper and silver impurities. Gold of higher purity can be made through the photoneutron process:[citation needed]

Mercury 198 + 6.8MeV gamma ray --> 1 neutron + Mercury 197 (half-life 2.7 days --> Gold 197 + 1 positron)

Sorry I can’t post the link, I’m new. Google: wiki synthesis of precious metals

My question is what happens to Mercury 197 if it’s hit by a 6.8 MeV gamma ray? If nothing happens then it would complete the decay to Gold 197. If that’s the case couldn’t you just put a naturally occurring substance that emits 6.8 MeV gamma rays in a container filled with Mercury 198 and wait for it to turn to gold? BTW I’ve read the threshold for gold is 8.1 MeV before it becomes radioactive.

If gold can be made this cheaply then the current price of $1562/ounce (about $600 when the wikipedia article was written) is a tad high since oil companies turn out thousands of tons of Mercury as a by product every year.

Assuming it’s not that easy, then if you radiated a thin layer of Mercury 198 (6.8 MeV is about the same energy level food is irradiated with) then waited two days, couldn’t you just use something like this:

Google: Scientists synthesize gold to shed light on cells' inner workings

to lump the gold atoms together cheaply, or maybe single gold atoms melt together cheaply?

Who knows, gold may even still work as money, and what a lovely way to get rid of toxic mercury – unless there are other plentiful elements that can be transmuted cheaply to gold.
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Check on the cost and liklihood of getting time on the machine (or building your own). I think you will find it will not be as cheap as you think it will.:)
 
7up said:
Likewise from same wikipedia source:

"Using fast neutrons, the mercury isotope 198Hg, which composes 9.97% of natural mercury, can be converted by splitting off a neutron and becoming 197Hg, which then disintegrates to stable gold. This reaction, however, possesses a smaller activation cross-section and is feasible only with un-moderated reactors."

This too still way to expensive?
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Not if you can pick up a sodium reactor really cheap and run it without paying anyone or doing any maintenance. The small cross section thing is very bad...since it is essentially a probability of a reaction occurring. since it is low, the yield would be very small.

glenn
 
7up said:
Likewise from same wikipedia source:

"Using fast neutrons, the mercury isotope 198Hg, which composes 9.97% of natural mercury, can be converted by splitting off a neutron and becoming 197Hg, which then disintegrates to stable gold. This reaction, however, possesses a smaller activation cross-section and is feasible only with un-moderated reactors."

This too still way to expensive?
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Some of the others are clearly better qualified than I to give a definitive answer. But I can't help wonder - after conversion of 198Hg to gold, what happens to the gold (now being exposed to a high flux of fast neutrons)? Probably not good things.
 
What is the likelihood of fusion getting to the point in the next 30 years where it is a viable energy source that makes gold cheap to make?
 
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