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Is it possible to make non-radiactive gold?

  1. May 9, 2010 #1
    I have heard that it is possible to make gold today, but it is radioactive. Is it possible to make gold or other non-radioactive chemical elements? We do find non-radioactive chemical elements in nature so why can't humans make them?
     
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  3. May 9, 2010 #2

    Vanadium 50

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    One could, but the amount of money it would take would never, every make it worthwhile. If one works very hard, and had a few million to spend, one might get a few milligrams of gold. A few dollars worth at best.
     
  4. May 9, 2010 #3
    Thanks, so it is possible to make non-radioactive gold today? Do you know how?
     
  5. May 9, 2010 #4

    Vanadium 50

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    Sure...dump a beam of ions into a target of mercury or lead. Wait for the radioactive gold to decay, and then chemically separate the gold. Repeat as needed.
     
  6. May 9, 2010 #5

    arivero

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    It is interesting to calculate the energies involved. You get some energy back at the end of the process.

    The reaction path is Hg 201 --> Pt 197 --> Au 197. If you want to avoid other (radioactive) elements, you need to purify the Hg before. This is probably the most expensive step, and highly dangereus because of the volatility of Hg. Poisoning is almost sure.

    With a target of lead, I doubt. With Pb, the energy balance is against you.
     
  7. May 9, 2010 #6

    Borek

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    I doubt it is more dangerous than dealing with - say - radioactive samples. In both cases you need to take care and use correct tools/procedures, but in both cases it can be done quite safely.
     
  8. May 9, 2010 #7

    arivero

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    Is it profitable anyway? Well, the world reserves of mercury are about the same size that the world reserves of gold -as it is to be expected, given they are so near in the periodic table-, so a public fabrication method of gold from mercury is not really relevant, it should only duplicate the reserves but at the cost of a doubly dangereus process (radiation + chemical poisoning). Thus the patent of the process is not very valuable as a global process. Note that global markets of mercury wil be closed in a few years due to enviromental and poisoning problems.

    Could it work as a private, small enterprise?

    Suppose you can devise a nuclear process with 30% efficiency. That should be you pay $200 for a kilogram of mercury, so it contains 131 grams of Hg201 and you get 39.3 grams of gold which yoy can sell at $40/gr, so you get a benefit of $1372 per kilogram.

    Can you scale the fabrication at a cost so low as $1300 per kg? I doubt it. Probably you need first to purify the Hg isotope, and the method to purify it is not dissimilar to the methods to purify Uranium. Perhaps you could get some cheap machinary from Iran if they decide to go out of bussiness.

    Then you need the nuclear process, ie you want to induce the alpha disintegration Hg 201 --> Pt 197 + He4. But you do not want to induce further alpha disintegrations in Pt 197 nor in the beta "subproduct" Au 197. And if you have failed in the purification process, you have disturbing absortions in the other Hg isotopes.

    While the process is globally exotermic, you need to compensate the energy loss by alpha particles which are absorbed or moderated in the walls of the container, so you will really need some nuclear source to keep the bussiness going. You need to study the best container. Also, do you want Hg to be in liquid state, or could an amorphous solid or even a solid crystal be preferable, in order to keep the alpha particles inducing a chain reaction? I am afraid that your cost of I+D is also accountable.
     
  9. May 10, 2010 #8
    Not going to work. You can't just induce Hg 201 to decay. If you hit it with an electron or a neutron, it's going to convert into something else before decaying. In fact, most isotopes of gold that you can create out of mercury by bombarding it with electrons will just decay right back into mercury.

    If electrons are out, you're left with neutrons and alphas. And that means you have to go down the periodic table, not up. Unfortunately, the first three elements before gold in the periodic table are even more expensive than gold.

    But is that such a bad thing, though? You could try to create them instead. Tungsten #74 is relatively cheap ($30/kg). You can bombard it with neutrons to induce beta decay and to create Rhenium #75 ($6,000/kg), or with alpha particles to create Osmium #76 ($100,000/kg), and possibly smaller quantities of Iridium #77 ($20,000/kg) and Platinum #78 ($50,000/kg). Neutron sources are quite expensive. Alpha sources are relatively cheap (besides, you can make a simple accelerator to accelerate helium nuclei) but they aren't very efficient, because you'll lose a lot on collisions with electrons. Someone could sit down and run some numbers.

    The most difficult part is, as you've mentioned, to separate the resulting elements. It's not particularly easy even to separate osmium from iridium and platinum, because all platinoids are chemically similar. But then you'll want to separate radioactive isotopes from non-radioactive ones. And that's no small task. The original separation method employed for the Uranium by the Americans in 1940's was to use gas centrifuges. Gas centrifuges only operate with gases and platinoids don't make compounds that are gaseous at room temperature. Besides, gas centrifuges are insanely expensive to operate in terms of electric consumption. Modern isotope separation methods are better, but you'll surely attract attention of the U.S. government (and the Iranians, too).
     
  10. May 10, 2010 #9

    arivero

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    Yes I agree that some agencies would be very worried about anyone interested on isotope separation...

    damm, you are right. I was thinking on some method hitting it with mid-energetic alpha particles, in the hope of inducing a "chain reaction" based on alpha. No idea about the calculations.

    With electrons, let me see, according http://atom.kaeri.re.kr you have some cross section (z,a) with electrons above 10 MeV. Then Iridium 197 goes beta (2.270 MeV ) and then Pt 197 goes beta again (0.719 MeV) to gold 197. Of course the combined energy of the alpha and the two beta will combine to counterweight the initial 10 MeV, but it is not easy to devise a method to reuse the particles. If we can not reuse the energy, then for 10^23 atoms the electricity bill is in the order of thousands US dollars, so not bussiness.

    We need a cross section for (a,2a) of Hg 201.
     
  11. May 10, 2010 #10
    What we need is some method of starting reactions with minimal energy. To do Tungsten-186 -> Osmium-190, we need 1.4 MeV alphas. To do Tungsten-184 -> Osmium-188, we need 2.2 MeV. In either case that's more than $20,000 worth of electricity per kilogram of product, assuming that we can accelerate alphas to MeV range, which we can't, and that 100% of our alphas will interact with tungsten nuclei rather than lose energy to brehms & ionization, which they won't.

    So unfortunately it seems that, unless there's some process that can be triggered by cool alphas (say, under 100 kev ... since that kind of energy can be generated fairly efficiently by high voltage vacuum chambers), alphas are out.

    Here's a new idea, then. Build a big deuterium fusion reactor. It's going to produce 2.5 MeV neutrons. Find a convenient process to produce platinoids or gold out of cheap elements. Insulate the whole thing with a thick layer of reactant. The challenge is to make the system big enough to convert a measurable quantity of reactant into platinoids or gold within our lifetimes. We should shoot for 10^16 neutrons/second.
     
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