What metal is this

[Alabama938]

So a couple of months ago I had to take down my whole set up and so the remaining pins and computer chips that I had I put in HCl and H202… every week or so I would recharge it with some H2O to for the past several months.

So present day oh I opened it, filtered it and dark green solution all removed… and now there is this light colored metal that appears to have gone into solution and perhaps come back out. It’s kind of binding everything together… Likewise there is kind of this gray slime that collected in the filter… A lot of the gold foils seem to be pretty freed up and came out in the filtration process

I guess I’m just looking for advice… What might that metal be, what might be advantageous way to recover the gold in this mess I’ve created

 

[g_axelsson]

You have large pieces of copper heat sinks on several CPU:s so I guess that what you call "metal" is actually a crust of copper I chloride. Try adding straight HCl to it and see if you can dissolve something. If it turns into a dark brown solution then it is the CuCl that is dissolving in the HCl.

CPU;s with all the gold already removed can be removed to speed things up.

Göran

 

[Alabama938]

Thanks for the insight, I can’t wait to get home and try this!

 

[Alabama938]

@goran

You were right on the . I pulled out all the chips and washed them with HCl… All the material that was clumped together immediately fell apart in fresh HCl and turned it a dark yellowish brown black. So I let it sit for a few hours and then filtered which is the picture you see below.

There is still some residual copper but small amount with the foils. What would you recommend as the next step? Drying and incinerating to then go to nitric boils, continuing with AP leach, or rinse till clear and use aqua regia. I really don’t want to incinerate because it’s difficult for me to set up and do in my neighborhood.

 

[nickvc]

With foils and powders you do not need to use AR, save your nitric for other processes,either hydrogen peroxide or bleach added to HCl will dissolve your gold fairly easily but make sure all metal is dissolved, incineration would be good but if your first drop looks dark simply re dissolve the powder again using the other oxidizer that’s should leave you with good clean powder.

 

[g_axelsson]

That looks great!

When doing copper chloride leach I usually run it until the liquid turns emerald green. Then there is only small amounts of copper left and the next step is aqua regia, HCl + hydrogen peroxide or HCl + bleach to dissolve the gold.

But then I seldom run pins in copper chloride leach, only foils from fingers. I just stockpile pins to either run it in a sulfuric cell or cyanide in the future, this will keep down the amount of waste and the pins can be sold with my other brass scrap.
I installed two fume hoods in my house this summer but I still have the duct-work to do before I can use them, so the future is near.

One way to mechanically separate the foils from the remaining pins is to use two beakers, add some water to the foils, swirl it and pour off the liquid before the foils have settled. Let the foils settle for a couple of seconds in the second beaker and pour back the water without the majority of the foils. Repeat until you are satisfied with the result.

With the majority of the foils separated from the pins it's easier to assess how much further you have to run the copper chloride leach. We all have our own preferences for work versus return, chemical cost, lab space... and so on. Maybe just add the remainder to the next batch.

Göran

 

[Alabama938]

Big thanks to everyone that lended their advice. Finally got all the copper rinsed out with acid, foils separated and I ended up using AR and SMB because familiarity level. Obviously it’s not a lot, but it’s got a nice color and that disaster is complete!!

 

[Topher_osAUrus]

Looks good.

I wouldn't consider it a disaster though.
It was just a familiarization with the nuances of AP.
Any mistakes made, wont easily happen again, as you, yourself, made them, and fixed them. They are ingrained in your mind, as stuff just 'sticks' better when its been a personal experience instead of reading about someone else's and attempting to apply it's lesson...
..you got to break some eggs to make an omelet, kind-of-thing. (..maybe that isnt the best analogy. I need coffee)