stamasd
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silver-copper-manganese-germanium alloy
I have a piece of silver-copper-manganese-germanium alloy that I made a little while ago in search of a metal with certain properties. It didn't turn
out how I expected it, and now I want to retrieve its components to try again with a different composition. Specifically I am interested in the silver
and the germanium (don't care much for the copper or the manganese).
Specifically the alloy was made of:
57.31g Ag
2.8g Cu
0.45g Mn
0.74g Ge
Specifically, my plan is to dissolve it in 60% nitric acid which should convert the silver, copper and manganese to the nitrates. I am not sure if the
germanium will react or not, and be converted to GeO2. From there, separate the germanium or GeO2 which should be insoluble, convert the silver to
chloride and separate it thus from the other dissolved metals, and further process the AgCl to get the silver back.
The main unknown is: will Ge remain as such or be oxidized by 60% HNO3 at room temperature to GeO2? And if the oxidation occurs, what would be the
best way to recover Ge from GeO2?
Germanium is actually much more expensive than silver, and I'd like to recover and reuse it if possible. 
Or is there a better way to approach this which would guarantee that at least the silver and germanium are recovered as elements?
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Texium
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Not sure about the germanium, but if you dissolve the mixture in nitric acid, you could stick some copper wire in the solution to recover the silver
as metal directly rather than going through the chloride.
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stamasd
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Well yeah but I want to recover it pure, not with a copper impurity. Because that way it will end up with a percent or two of copper mixed in. And the
chloride way is not much more hassle.
The germanium though is the main question. Because I don't feel like reducing GeO2 with hot hydrogen. Making the hydrogen and heating wouldn't be a
problem, but bad things can happen which I'd prefer to avoid.
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Boffis
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After dissolution/oxidation with nitric acid the three metals will dissolve and the silver can be cemented on copper wire from which the silver is
easily removed.
The germanium will mostly remain in the insoluble residue. Filter off and distil the insoluble residue with 6-8M hydrochloric. The germanium distils
over as the tetrachloride which can be extracted with ether. I am not sure how you recover germanium from its tetrachloride, you will have to do a
little research of your own but it may be possible to cement it with zinc or manganese metal.
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stamasd
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I really don't want to deal with GeCl4, it's a very nasty chemical.
And the way from GeCl4 to element is: hydrolysis to GeO2 (the tetrachloride is very water-sensitive) and then reduction with hydrogen. Which I already
said I'd rather not do.
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Sulaiman
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First, to not answer your question:
IF you are considering a slightly different composition for your next experiment,
could you modify the existing alloy to meet your requirements?
If this were my problem I'd consider:
. Will the cost and time invested be worth the result?
(at best, four products of unknown purity plus waste)
. Can I cast this alloy into a souvenir ?
.........................
If going the wet chemistry route then you need to get the alloy into solution
Quickest is when the alloy has a large surface area, beat it into a foil or melt and pour into water etc.
Quick but inefficient violent would be conc. Nitric
Dilute (<=3M) Nitric plus time (and an occasional swirl) may be a good start ?
(an air bubbler would be beneficial)
Then you can slowly evaporate to concentrate or crystalise or react.
Just whilst planning a 'good' route, to save time.
CAUTION : Hobby Chemist, not Professional or even Amateur
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bnull
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I'm sorry to say but your germanium is probably gone. You have only a few ways of recovering it as an element again, and those ways you don't want.
There is a chance some of it will be converted to germane, GeH4, which is a toxic, inflammable gas. Being inflammable and toxic is not much
of a concern given that it won't be all produced at once. But it is a gas and gone it will be. Germane may also react with nitrogen dioxide and
generate small particles of germanium dioxide, which are not so easy to capture. You see, the prospects for a complete recover of germanium are not
good. You'll be losing what, ten bucks of germanium?
After dissolving the alloy in nitric acid, add sodium chloride. Silver chloride precipitates, everything else remains in solution. Filter and wash the
precipitate, which will be a mixture of silver chloride and germanium dioxide (if the latter wasn't small enough to go through the filter unharmed).
Silver chloride is soluble in excess of chloride ions, while germanium dioxide is not. Germanium dioxide is soluble in alkali and possibly ammonium
hydroxide.
Homemade sterling silver or Argentium, was it?
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stamasd
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A variation thereof indeed.
Quote: Originally posted by Sulaiman  | First, to not answer your question:
IF you are considering a slightly different composition for your next experiment,
could you modify the existing alloy to meet your requirements? |
Not really, because it has too much of one component and I need to remove the excess. Adding enough of the others to achieve that would become
prohibitively expensive and would result in way too much product. The amount I have made previously is already a large excess.
| Quote: Originally posted by Sulaiman |
If this were my problem I'd consider:
. Will the cost and time invested be worth the result?
(at best, four products of unknown purity plus waste)
. Can I cast this alloy into a souvenir ? |
I'm doing this for fun, time is irrelevant, cost somehow but secondary. 
The alloy is already in the form of a thin sheet with a large surface area. Probably will go with the dilute nitric acid dissolution plus air bubbler.
Will update once done.
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Sulaiman
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Have you considered that a portion of your alloy would contain the same ratio as the original ratio of each element
So you can use enough of the original alloy to provide all of the required element that is presently in excesss.
eg if your new alloy only needs 1/10th the quantity previously used in excess
then use 1/10th of the existing alloy.
Once you start chemical operations you will never be sure of ratios.
CAUTION : Hobby Chemist, not Professional or even Amateur
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Bedlasky
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I think Ge will be oxidized to GeO2 (tin is oxidized to SnO2, so it wouldn't surprise me). You can try reduction of GeO2 with carbon, Al or Mg, but
make some research on that, I just very quickly searched it.
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clearly_not_atara
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Germanium is slightly more electronegative than hydrogen in aqueous solution, so it can be reduced electrolytically in water. | Quote: | | Germanium can be deposited electrolytically from strong aqueous KOH solutions of the dioxide. |
https://iopscience.iop.org/article/10.1149/1.3498019/pdf
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bnull
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I was thinking about that last night, if germanium could be recovered from molten germanate.
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Rainwater
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Sulaiman i think has the best idea
Running some numbers.
GeO2 + X = Ge + Bs
So
H2 + 430c. Ya my ears are ringing just thinking about hot hydrogen
Al ... owww termite with a ΔG= -1660.22 sould produce some distillate of the product. Good luck collecting any.
C + 570c endothermic and easy to seperate a gas.
Pyrolysis with carbon, its like the missionary position of metal refining.
Tried and true.
Fe + 530c
Cu looks good. Lets try a displacement ... naaa would need -90c kinetics would be eternal
Preview/post glitch
Liquid Na metal should work aswell. Kinda safer than hydrogen.
[Edited on 20-12-2024 by Rainwater]
"You can't do that" - challenge accepted
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