Give me a reality check, please. :)

[Tquilha]

Hello all.
I've been interested in precious metals recovery as a hobby for a very long time and this forum is one of the very best resources I've found in my searches.
So, I've read Hoke's book, I studied quite a bit (was nice going through some of my old Analytical Chemistry books...) and now I think I have a nice idea for my first experiments, but want to run it through you for some ideas.
I'll be processing pins from CPUs (mostly intel P4s and some mobile AMDs). As far as I know, all those pins are magnetic (kovar?)

Strip the pins from the CPUs with a heat gun, save the rest for later processing.
Soak them in 33% HCl for a week, with a bubbler to provide agitation, then decant the liquid and add some more HCl but this time with H2O2 (1 part peroxide to 3 parts acid).
Keep the bubbler going and soak until I can't detect any more magnetic material.
Filter and dissolve the gold with HCl+bleach, filter again and drop the gold with SMB.

How many mistakes do I have here?
Thanks for your help.

 

[FrugalRefiner]

Soak them in 33% HCl for a week, with a bubbler to provide agitation, then decant the liquid and add some more HCl but this time with H2O2 (1 part peroxide to 3 parts acid).
Keep the bubbler going and soak until I can't detect any more magnetic material.
Filter and dissolve the gold with HCl+bleach, filter again and drop the gold with SMB.

How many mistakes do I have here?

If you add H₂O₂ along with your HCl, you're probably going to dissolve some of your gold. If you leave it long enough, and if there is enough base metal left, any gold you dissolve will probably cement back out as a fine gray/black powder, so you should be able to recover it when you dissolve the foils, but it's best not to dissolve any of it while you're trying to eliminate the base metals.

Dave

 

[archeonist]

I do think 1 to 3 peroxide HCl will probably dissolve your gold too, why this step? I would boil them in HCl and if all is dissolved you dissolve your gold in AR, it will be a bit of a dirty drop but that's how I do them.

 

[kernels]

Boiling HCl without a proper fume hood and scrubber is probably not a good idea.

It all seems quite simple when you list the steps out, the devil is really in the details. But if you feel that you are well enough set-up to experiment safely, then the best way forward is to make a start and see how it goes.

If you take good pictures of your progress and ask polite questions, we are very happy to help you as you go.

 

[archeonist]

Boiling HCl without a proper fume hood and scrubber is probably not a good idea.

It all seems quite simple when you list the steps out, the devil is really in the details. But if you feel that you are well enough set-up to experiment safely, then the best way forward is to make a start and see how it goes.

If you take good pictures of your progress and ask polite questions, we are very happy to help you as you go.

Who says he hasn't a proper fume hood?

 

[kernels]

Who says he hasn't a proper fume hood?

I do.

Telling someone to go boil some HCl without any additional safety and process information is negligent.

Very very few people who are just starting out and simultaneously asking simple questions about a simple process have access to a fume hood and scrubber.

 

[archeonist]

Who says he hasn't a proper fume hood?

I do.

Telling someone to go boil some HCl without any additional safety and process information is negligent.

Very very few people who are just starting out and simultaneously asking simple questions about a simple process have access to a fume hood and scrubber.

Maybe you can tell him he should wear safety glasses and gloves? And maybe you can tell him to handel these chemicals outside?
You have a point there, but let's not go into a discussion here.

 

[Wingedcloud]

Hello.

I usually do those pins with a warm to hot HCl leach (no need to boil, in my opinion), to remove the tin and some base metals, followed by a good water wash and a nitric leach. You will remove much more base metals with a nitric leach before your AR leach for gold, making your AR solution much cleaner for the SMB gold drop.

I can't stress how important is that you wash your pins well in between the HCl and nitric leaches, otherwise you might lose a bit of gold, because if HCl remains in the pins, when you do the nitric leach, a bit AR will form and dissolve your gold.

However, now that I give it a second thought, maybe, even if this happens, the little gold dissolved will cement back out on any base metals nitric hasn't dissolved yet, but I would need confirmation from more experienced members.

Also, unless you are processing a large amount of pins, don't expect a fair amount of gold from that material. It is relatively low yield.
And, since it's your first time running a gold recovery process, it's all natural that somethings will happen that you are not expecting, that will cost you some gold. Happens to everyone at the beggining :lol:
Either way, if you are really into it, don't throw anything away unless you are sure there's no gold in it, and keep searching and learning

Winged.

 

[Tquilha]

Thanks for all the help so far.

kernels is right, right now I don't have a fume hood, I'm doing my experiments outside with proper personal protection. I really would like to avoid boiling HCl for my first experiments.
So, instead of HCl, decant and HCl/peroxide; how about HCl leach with low heating, and then adding fresh HCl when the reaction slows/stops. React until magnet shows no more magnetic material, filter and then HCl+bleach (or HCl+peroxide) to dissolve gold. Filter and drop with SMB.

I don't have any ideas about getting rich doing this. I'm doing this for knowledge and as a hobby only.

Have fun

 

[kernels]

How much of the Kovar pins do you have ? From memory CPU pins are around 3g Au / kg, so you would need around 300g to end up with enough Gold to work with easily.

It can be difficult to learn with very small amounts of Gold and CPU pins is not the easiest scrap to learn with, but I don't want to put you off.

With a bit of patience and good sense you can definitely recover the Gold from them and this is a fantastic hobby.

I would be inclined to just dissolve the pins in AR directly, then use Copper to cement the Gold out of the 'dirty' solution, then re-refine the Gold. The AR would still have to be hot (75 ish degree C), but at least not boiling.

This video shows the direct AR process -> https://www.youtube.com/watch?v=QjjE6xw6NBo and ends with a good spreadsheet of the yields from various processors

 

[Tquilha]

Thanks kernel.
I' ve read quite a bit and watched quite a few videos about the whole process (about several processes...) and decided to stick with the HCl/Bleach method for now.
Two reasons: Hydrochloric acid and bleach are pretty cheap and easy to find here in Portugal, while nitric acid is more expensive. Also, my PPE are good for chlorine and for HCl fumes, not for NOx.
So far, my first experiment will use 98 CPUs (part AMD part Intel, all from laptops). My estimates say I'll get about 120 g of pins.
So I'll expect some 0.3g of gold.