How do I proceed?

[zorba]

Hi there. So know i´m packed with knowledge and have given my first try on recovering and refining some Au.

I started with soaking 5 CPU:s in some nitric (tech.) do dissolve the base metals. I left it for about 2 days, following the procedures pointed out in Hokes.
During the whole process I only saw the brown fumes, which were said to appear, 1 time (though it may have occurred other times, I left it between long intervals). That was just before the washing treatment (hot water on the gold, rinse) were i added some more nitric to assure that the baste metals were dissolved in the water. Through the time before that the nitric had worked on the CPU:s in a way that made the gold fall to the bottom and giving the solution a greenish color. So after filtering the solution into another beaker and rinsing the gold thoroughly, I dissolved the gold left in the beaker together with the CPU:s (to be sure that all the gold follows) in AR. The AR immediately worked on the gold, dissolving it, but the color changed to greenish indicating that there were base metals left (copper obviously). Stannous test showed that there were gold in the solution.

The plan was to remove the base metals completely before recovering the gold, as it should be, but now I stand there with a solution containing gold but contaminated with those freakin base metals :x

So I need your opinion guys, should I proceed with removing excess nitric and then precip with SMB or is there any other method which can purify my solution from the copper? As I have understood the gold will still drop with SMB nevertheless if the solution contains copper, as long as the nitric is out of the way.
Then I can rinse it several times in HCl as planned, or go back to nitric and attack the metals.
Please, enlighten me :idea:

 

[jimdoc]

What CPUs were they?
Ceramic or Fiber P-3,P-4s?

Jim

 

[zorba]

What CPUs were they?
Ceramic or Fiber P-3,P-4s?

Jim

Oh sry, forgot to mention.

Ceramic, pretty old. Can´t recall whether it was AMD or Intel

 

[butcher]

I would try de-noxx and SMB, if not a lot of copper, the most of copper would stay in solution, this recovered gold can be refined, something to consider CPU have metals inside ceramic shell, these metals are hard for acids to reach unless CPU is powdered, these metals can cement some of the gold you dissolved into solution, and added base metals to your solution.

If SMB approach fails you can always recover gold using cementation on copper from solution.

Since you have had your nose in Hoke's book I do not have to remind you to use stannous to test your solution to see when it is barren of dissolved gold.

I powdered CPU's and leached them again to get that last little bit.

Some CPU’s have kovar pins, and heat sinks should also be removed.

 

[zorba]

I would try de-noxx and SMB, if not a lot of copper, the most of copper would stay in solution, this recovered gold can be refined, something to consider CPU have metals inside ceramic shell, these metals are hard for acids to reach unless CPU is powdered, these metals can cement some of the gold you dissolved into solution, and added base metals to your solution.

If SMB approach fails you can always recover gold using cementation on copper from solution.

Since you have had your nose in Hoke's book I do not have to remind you to use stannous to test your solution to see when it is barren of dissolved gold.

I powdered CPU's and leached them again to get that last little bit.

Some CPU’s have kovar pins, and heat sinks should also be removed.

Thanks! I appreciate your answer. So I believe that I did not prepare the CPU:s correctly for the nitric to reach all the parts.
What do you mean with "powdered", how do you prepare them before removing the base metals?

 

[patnor1011]

He most likely meant that he crush them to small pieces.

 

[butcher]

Yes I grind them to powder to leach them a second time, I have not worked with many CPU's for a while now, I do not run across many anymore.

breaking them to small pieces works good for first leach, as fine powders are a bit more of a challenge to leach.

 

[zorba]

Yes I grind them to powder to leach them a second time, I have not worked with many CPU's for a while now, I do not run across many anymore.

breaking them to small pieces works good for first leach,

I´ll try that!

as fine powders are a bit more of a challenge to leach.

I thought the nitric reached the metals easier in powdered form?

 

[patnor1011]

With fine powder there may be some issues with filtering. Most of people use vacuum set up it is much faster.

 

[goldenchild]

Instead of crushing the cpus you are better off getting just the legs off. Samuel's technique is great for that.

[youtube]http://www.youtube.com/watch?v=hD6mE5-hPWM[/youtube]

 

[rewalston]

Excellent video Goldenchild (and Samuel as well). Quick question will a mapp or propane torch work as well? Right now don't have the money for anything else. I assume (hate that word) that once all the pins are removed the rest of the CPU is set aside for a later date to crush and go after anything inside them?

Rusty

 

[Barren Realms 007]

Excellent video Goldenchild (and Samuel as well). Quick question will a mapp or propane torch work as well? Right now don't have the money for anything else. I assume (hate that word) that once all the pins are removed the rest of the CPU is set aside for a later date to crush and go after anything inside them?

Rusty

Yes to each of your questions.

 

[rewalston]

Thanks Barren. This might just make it a little easier

 

[goldenchild]

I think it was mentioned by lazersteve that he has never found anything inside of ceramic cpus after crushing them. I'm not sure you will get anything more than face value out of ceramics.

 

[rewalston]

Thanks goldenchild. I have a couple of chips I pulled off a motherboard the other day that doesn't have any pins whatsoever. They are ceramic on the top with a thin fiberglass pad underneath that was soldered directly to the board..they are marked with a gold arrow on a corner so I pulled them. unless there is gold between the fiberglass and the ceramic I'm not sure where else it would be.

Rusty

 

[martyn111]

Thanks goldenchild. I have a couple of chips I pulled off a motherboard the other day that doesn't have any pins whatsoever. They are ceramic on the top with a thin fiberglass pad underneath that was soldered directly to the board..they are marked with a gold arrow on a corner so I pulled them. unless there is gold between the fiberglass and the ceramic I'm not sure where else it would be.

Rusty

These are commonly referred to as flat packs and do contain gold between the fibreglass and ceramic/plastic parts

 

[rewalston]

Thanks martyn

 

[lmschers]

i know this is a suuuper old post. but i'm doing my homework. just got 30 CPUs to work on.

for the original question though:
wouldn't electrolysis work to get the copper out of a solution.
would it cement out the gold if you used a copper electrode?

 

[Harold_V]

for the original question though:
wouldn't electrolysis work to get the copper out of a solution.
would it cement out the gold if you used a copper electrode?

It's not that simple. If you introduce electrodes that are made of base metals, they will cement the values. Best one recovers the values by cementing on copper, then refine for purity. Alternately, precipitate as usual, then wash well and re-refine for purity.

You would be well served to add heat to the digestion of base metals. How ANYONE processes without added heat is a total mystery to me. It leaves too much to guess work.

Harold

 

[lmschers]

ok, that's what i thought.

i would use a copper wire on the negative end.
and then a carbon electrode (pulled from a D size battery or something larger) on the positive end.
and just run the reaction till the solution is no longer greenish.

that should fill up the solution with a lot of black carbon that would need to be filtered out of the remaining solution.
i need to try this to see how much gold would be left in solution.

and then alternately, i would have to re-refine and test the copper wire that i coated.... to see how much gold would be sucked up.
____________________________________________________________________

i was thinking about this because electrolysis seems to be the best way to separate copper and silver.
but that's because there's no cementing going on.
is there some cathode that you could use instead of copper that would still suck up the copper?
i think stainless steel and aluminum both work for silver.