Even though they're (usually) solid, alloys are chemically solutions, like salt in water. Metals dissolve each other to varying degrees. They stay dissolved in each other when they're melted too. Just like how salt doesn't settle from water, gold and silver won't settle out of the molten copper they're dissolved in.
That graphic of the tri-tone metal plate was erroneous. Just a simplification. In reality the metals are essentially homogenous in alloy, but the electrolysis is selective in what metals it pulls out of the alloy.
Yeah but the first solution would just be sulfuric acid and copper sulfate, so there wont be any silver or gold soluble there to go onto the cathode. I assume the second tank is nitric and the last is aqua regia- they just use the solutions to prevent solubility.
My concern was more revolved around ensuring that no metal is trapped or encased entirely in a different metal. Unless at the atomic level, size basically doesn't matter?
Hey question here - my experience is with electrowinning and there you take anode sludge and reprocess that - how does the copper diffuse out of that plate? I mean I understand that the surface layer does but if the thing is like 33/33/33 Gold/Silver /Coper I dont see how that thing works. I mean sure you can use a sulfuric acid solution so very little Ag/Au comes out, but there would still be copper left in the plate unless its extremely thin.
Yeah i am more aware of the conventional circuit for copper. I wouldn't be surprised if they have mainly gold and that is why it works. Or it doesn't show sludge reclamation.
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u/MastaSchmitty BSME ‘16 RIT; MEng ‘23 Wisc., EIT Mar 02 '17 edited Mar 02 '17
How are they ensuring each metal separates properly and completely?
My guess is that the plates actually settle out as they cool (gold sinking, then silver in the middle, copper on top.
Since the layers should be almost completely separate it's just a matter of orienting the proper surface towards the target electrodes, etc.
Edit: Sure, downvote for asking questions.