So I used 15 ceramic CPUs 14 of those were the AMD purple (as shown in pic 1) and one was a 486 that got slipped in there. I used a torch to remove the mlcc's, the silicone dye I think that's what it's called, and the little black rubber spots. I broke up to 486 for the gold bonding wires but the other than that I left everything intact. Put in distilled water and nitric acid and some heat and the pins fell off of the CPUs. But the base metal within the pins stay intact. I was worried maybe there was tin or something that was delaying this process but before I did all of this I put all CPUs in a HCL boil to get rid of any solder or tin. I then rinsed with distilled water and then put in nitric acid and distilled water. Forgot to tell you that. Does anyone know what I'm doing wrong? Or am I just being impatient? The CPU left in the solution is the 486 I'm trying to get the gold bonding wires to get the gold off of them. I usually use awkward regio with this but I wanted to try nitric acid and distilled water. And watch the gold foils float up after the base metals have been dissolved. Did I use it the wrong method? I thought both were equally usable but could I be wrong? There's a good chance of that!
Nitric not taking base metals out of gold-plated pins off of ceramic CPUs
- Thread starter Rreyes097
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maybe tin. did you heated the reaction ? this often speed up the process vastly.
i recommend to salvage all the solid leftovers, put them in aqua regia and dissolve everything applying some heat (caution should be taken, beware of runaway rxn - use big beaker). rinse the solids, filter it, then denox the solution (evaporating down-adding HCl, or better with sulfamic acid) and drop the gold using SMB or sodium/potassium sulfite, or anything. this should work fine, ive done it numerous times
from my point of wiew, proceeding with nitric, then filtering gold foils, again dissolving with AR, filtering, dropping... reqires much more effort than just directly dissolving crushed CPUs in AR. for weight, the base metal content is relatively low, in comparison with eg pins. ive done this at least 3 times, with batches up to 1,5 kg. purity of gold for this route (i boil the gold ppt with HCl anyway to get rid of Ag/Pb) never going below 99.8 % (XRF tested) usually being 99.9 %.
i recommend to salvage all the solid leftovers, put them in aqua regia and dissolve everything applying some heat (caution should be taken, beware of runaway rxn - use big beaker). rinse the solids, filter it, then denox the solution (evaporating down-adding HCl, or better with sulfamic acid) and drop the gold using SMB or sodium/potassium sulfite, or anything. this should work fine, ive done it numerous times
from my point of wiew, proceeding with nitric, then filtering gold foils, again dissolving with AR, filtering, dropping... reqires much more effort than just directly dissolving crushed CPUs in AR. for weight, the base metal content is relatively low, in comparison with eg pins. ive done this at least 3 times, with batches up to 1,5 kg. purity of gold for this route (i boil the gold ppt with HCl anyway to get rid of Ag/Pb) never going below 99.8 % (XRF tested) usually being 99.9 %.
Alabama938
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Doesn’t that give you such a dirty black solution, difficult to filter, difficult to tell when all the metal has been dissolved so there is no gold cementing. This is what plagued me when I tried straight AR. I much prefer the AP Leach for this stuff now it really cleans out the iron and tin pretty well it seems.
If you have any tips about concentration or ways to make direct AR easier or cleaner I would love to hear… I just really hate those black solutions, like so yellow they’re black from iron I think.
If you have any tips about concentration or ways to make direct AR easier or cleaner I would love to hear… I just really hate those black solutions, like so yellow they’re black from iron I think.
of course, solution is dark, but i never see it as a problem. it make sense from point that chloro-complexes of all metals form, which have much higher absorbtion coefficients than nitrate soln. typically reaction self-sustain the necessary heat and everything dissolve on its own. if you worry that something undissolved causes cementation, just decant the solution to another beaker and inspect
obtained solution is denoxed and cooled down to ambient temperature, filtered and directly dropped. i had no problems with this approach. only when the gold content is very low, there could be problem forming dense ppt, so it settles like overnight. personally i preffer this route. of course ive done it multiple times with HCl/air bubbler (vast ammount of low-grade material) or with 30-40% nitric, but from practical aspect (not aesthetical ) i never do it again.
with batches of CPUs, silver "spacers" from under the pins remain in the solution, but the cementation on these is minimal. i filtered them separately, dissolve in nitric acid, filter, and the residue was boiled in AR. ammount of gold in the residue was minute enough that after cementation of all metals on zinc, XRF werent able to measure the gold content of ppt.
pictures are from batch of pins. but the overall story is the same also with CPUs.
obtained solution is denoxed and cooled down to ambient temperature, filtered and directly dropped. i had no problems with this approach. only when the gold content is very low, there could be problem forming dense ppt, so it settles like overnight. personally i preffer this route. of course ive done it multiple times with HCl/air bubbler (vast ammount of low-grade material) or with 30-40% nitric, but from practical aspect (not aesthetical
) i never do it again.with batches of CPUs, silver "spacers" from under the pins remain in the solution, but the cementation on these is minimal. i filtered them separately, dissolve in nitric acid, filter, and the residue was boiled in AR. ammount of gold in the residue was minute enough that after cementation of all metals on zinc, XRF werent able to measure the gold content of ppt.
pictures are from batch of pins. but the overall story is the same also with CPUs.
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when dropping the gold, i usually grab my phone and switch on LED light, aim it on the bottom of the beaker and if some ppt is present, it is clearly visible. usually i decant the solution to another beaker and let it sit for few hours, than inspect again for ppt (if i lost something in the first decant). i had also good results with siphoning the solution.
when pouring the dark liquid off, you could assemble a good strong light under it to see, if some ppt is passing from the bottom but i needed it like once when my light in the room died out
richer the mother liquor in Au is, more dense ppt is formed, thus you can decant in few hours or in like one day. with low grade metal stuff like modern PC pins (under 1g/kg) this process is inefficient when it comes to gold drop (usually extremly fine suspension form). electrolysis methods or AP or HCl/air is then more "clean" and straightforward, even with multiple more steps
when pouring the dark liquid off, you could assemble a good strong light under it to see, if some ppt is passing from the bottom
but i needed it like once when my light in the room died out richer the mother liquor in Au is, more dense ppt is formed, thus you can decant in few hours or in like one day. with low grade metal stuff like modern PC pins (under 1g/kg) this process is inefficient when it comes to gold drop (usually extremly fine suspension form). electrolysis methods or AP or HCl/air is then more "clean" and straightforward, even with multiple more steps
Geo
Well-known member
Add a little sulfuric acid. The base metal is an iron based alloy called Kovar. While not quite stainless steel, it is very resistant to attack from just nitric acid. The amount of sulfuric acid needed is subjective. Start with 10ml's. If no reaction shortly after adding, add another 10ml's. The reaction will start slowly but ramp up quickly.
