Depopulating ram with HCL

[resabed01]

What I did was depopulate about 35lbs of ram sticks with HCL. It went well considering I needed to do all 35lbs in 3 batches, re-using the HCL. The last batch went considerably slower than the first. I tried to keep the batches covered to keep out oxygen, only opening every so often to mix the ram sticks to eliminate dead spots in the solution.
So now I have about 1.5 gallons of spent acid which I'm assuming is mostly stannous chloride. Also there were considerable metallic powders that dropped out which I will be processing to hopefully recover silver from.
I have a couple of questions here; The spent HCL is a nice transparent purple color, is this colloidal gold? If so how do I recover? I noticed over time it wants to settle... very slowly.

The used solution, how do I treat for waste? Could I simply evaporate the water and remainder HCL and recover stannous chloride crystals? Not that I need the salt, Stannous is easy enough to make on demand. Or would it be better to drop the tin out and adjust Ph to neutralize?

Thanks.

 

[ericrm]

no the purple is not gold, droping tin and adjusting ph will not make it ok to be disposed of... look for lazersteve disposal method ,i cant find it right now on my side... you will have to drop all the metal as hydroxide in a specific ph patern ... if someone has it on hand, it would be nice to put a link ... i forgot your stannous chloride is contaminated with other metal i would not use it as it is

 

[steyr223]

I have the same process going on
I have a question concerning the boards
After the black memory ic's were removed o left
The boards in hcl to see if the mask would be removed
After all I could see where some of it
that had already been removed

When i rubbed the boards with my fingers i noticed
The mask came off easaly but so did the gold

So now i have gold foils mixed with many many tiny
Electronic parts and stuff (i had done many various boards
Before the memory

What would be my best avanue in seperating my au

I have some thoughts but would like to here more
All coments welcome
Thanks steyr223

To op how long did you leave material in hcl
Thanke

 

[butcher]

Basically separate powders and garbage from the larger pieces like memory chips, wash and incinerate powders, to clean them up, removing trash and base metals before dissolving any gold.

If you do not have much of this solution (as there would not be much gold in it), save it up with the stock pot method, until you have enough of the value containing powders to make treatment worth the effort.

Use a acid resistant strainer to separate, the liquid and smaller powder from the chips and larger materials.

Let the solution settle well, decant acid from powders.
add them to stock pot or treat them further.

Boil powers in water, lower heat to let powder settle but keep solution hot as possible, decant rinse water while hot to remove lead chloride, put the solution in a jar to cool when cool the lead chloride will form a white crystal precipitant or salt, add fresh water and repeat the hot rinse of the powders, the first rinse water after cooled can be reused to pick up more lead if needed (to conserve on volume of waste solution generated), sometime small traces of values can be carried with the rinse water washes, I keep a jar of lead chloride that I can go through it again later to recover any value from the lead, this lead can also be converted to lead oxide for other uses later like as a collector in a melt.

Mix up a solution of NaOH in water, rinse the powders, decant solution and rinse again with a couple of warm water rinses, this helps to convert HCl acid to NaCl which will rinse out it can also help to form oxides of some of the fine base metal, let powders settle well before decanting the solution.

Dry and incinerate the powders to red hot keep powders crushed and stirred well to get good air exposure while roasting them, this burns off carbonous material,will help to oxidize base metals making them easier to dissolve into acid, and helps to oxidize any tin that without this treatment could give much trouble in later processes.

Now the powders are prepared for further treatment, here (with your powders) you should not have large pieces of base metal like copper, a boil in HCl, lower heat, spray in a little water, let powders settle well, decant with solution warn to hot, the color of solution as you give a few hot water rinses can indicate if another HCl treatment may be needed.

If these powders had undissolved pieces of copper metal, or copper metal powders a copper II chloride leach with mild heat can dissolve the copper.

As far as the memory chips Patnor and No Idea gives good details for processing them.

 

[resabed01]

To op how long did you leave material in hcl

I did the memory sticks in 3 batches. The first went quite quickly, I think I left it in for about a day.
The second went slower, about 2 days and the third took about 4 or 5 days to complete.

I noticed if the boards were left in too long, the mask wanted to come off and the MMLCs were falling apart.

I now have the barren boards in AP to remove copper. The metallic powder from the solution and washes have been separated and will be processes as per Butchers advice. I have about 300g of MMLCs from this.
It will be interesting to see what I recover in gold, silver and other PGMs

 

[solar_plasma]

and the MMLCs were falling apart.

...then don't forget the palladium...if they already fell apart, some of it could be dissolved, I think. I believe you will now need twice of the time you have saved in the beginning to recover now. At least your chips are clean of solder now.

@butcher
You are really amazing!

 

[chlaurite]

...then don't forget the palladium...if they already fell apart, some of it could be dissolved, I think.

I didn't think PGMs would dissolve in straight HCl, without a strong oxidizer?

In any case, I've recently seen what he describes (though I tried it on just a handful of small boards, not 36lbs :shock: ), and even if he lost some PMs, he can most likely still salvage most of them by fishing the MLCC end-caps out of the mixed crap that fell off the boards (or in my case, they didn't actually "fall" off the board, but rather, the whole body of them vanished leaving the end caps attached so lightly you could wipe them off just with a finger)


Resa: Try using a more dilute acid, and only leave your boards in there until you can easily pop chips off them (poke 'em with a plastic rod once or twice a day). At a concentration of 3M, it took just about a week, which fits perfectly with my 9-to-5 schedule (start on weekend #1, end on weekend #2).

 

[solar_plasma]

wiki(ger)

Es löst sich in Salpetersäure, wobei Palladium(II)-nitrat Pd(NO3)2 gebildet wird. Es löst sich ebenfalls in Königswasser und in heißer konzentrierter Schwefelsäure. In Salzsäure löst es sich bei Luftzutritt langsam auf unter Bildung von PdCl4 2−.

Amazing, the german wikipedia tells much more about palladium than the english version....well, it says, Pd dissolves in HNO3, AR, hot conc. sulfuric acid and in HCL slowly if there is O2 from the air available. So, if air is an strong oxidizer to you, you are right.

 

[steyr223]

Thanks butcher
I enjoy reading your short expinations :shock:

Thanks to the op
Btw i took all my ic's out as soon as they came off
I left the sticker on which covered 4 of the 8 chips
All 4 would stay together for collecting

Thanks steyr223 rob

 

[chlaurite]

So, if air is an strong oxidizer to you, you are right.

I stand corrected - Good to know, Thank you!

So, when depopulating with acid, do it in an inert or weakly reducing atmosphere if you hope to later reclaim any palladium. Easy enough - Argon, or better, CO, in a container with a bung airlock* will work for that. 8)

Of course, more realistically, I haven't gotten to the point where I think I could successfully recover PGMs - Though I have saved up my MLCCs for later. More Hoke for me, before I turn all of those into a useless toxic sludge.


* The HCl and metal will produce hydrogen, itself a reducing gas, so we don't want the container tightly sealed, we just need to displace any oxygen there to start with and keep any from getting back in.

 

[solar_plasma]

You know, most I say is more theoretically thought...I don't believe there will be much getting dissolved, I just wanted to have mentioned, because it may be an idea to test for Pd at this point. I use air stirring and 40degC all the time and though there have been maybe 20 ml ceramic resistors in it, I didn't test positive for Pd - maybe those resistors didn't contain any Pd...you see, I don't know.

 

[chlaurite]

No worries, I enjoy the discussion whether I end up right (good) or wrong (better, because then I learn something and don't waste PMs or get hurt 8) ).

As an aside, though, I don't think I'll use acid for depopulating anything but RAM from now on. I tried it on a small batch of a few mixed boards last weekend (as I described), and everything looked beautiful - Chips and pins just falling off at a light touch, even some of the laminate coming off the boards. And then I started trying to clean up.

I poured off the acid, planning to reuse it. Great, no problems yet. Lightly rinsed off the boards with warm water, figured I'd evaporate that down a bit and put it in the "mixed metal chlorides pending conversion to hydroxides" waste bucket. No problem there either (most notably, the runoff from that DIDN'T show the problem I'll mention next - Probably because I used warm water).

To make sure I didn't have any stray modestly-strong acid hiding under chips, I put the boards into another bucket to soak for a few hours in plan o'l water. Half an hour later, the water in that bucket looks almost exactly like milk.

At first I suspected (based on Hoke, ch.7) that I got lucky and had a lot of silver in the solder on one of the boards I used, but I actually have the bucket sitting out in the sun and it hasn't turned black yet. As far as I can tell, that leaves lead. Two gallons of awful, awful lead chloride in a suspension that doesn't want to settle to the bottom.

Ah well. Off to the shed to let it evaporate down to something manageable, while I see if Ms. Hoke has any further advice on this one.

 

[solar_plasma]

Ammen p.243 at least a nice idea, what lead chloride can be good for

 

[chlaurite]

"Electrolyte: Molten Potassium". :lol:

I think I'll leave that one for much, much later in my skill-growth.

 

[solar_plasma]

"Electrolyte: Molten Potassium". :lol:

I think I'll leave that one for much, much later in my skill-growth.

Nope, potassium chloride. Which doesn't make it easier (mp. 773degrC), but muuuuuuch saver than molten potassium :lol:

 

[ericrm]

no the purple is not gold, droping tin and adjusting ph will not make it ok to be disposed of... look for lazersteve disposal method ,i cant find it right now on my side... you will have to drop all the metal as hydroxide in a specific ph patern ... if someone has it on hand, it would be nice to put a link ... i forgot your stannous chloride is contaminated with other metal i would not use it as it is

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=36&t=11637&p=168081&hilit=hydroxide+chart#p168081 the link for the acid disposal...

 

[david379]

HI

Does somebody know where can I read - how to recover gold from RAM fingers?
I have visited http://www.goldnscrap.com , but there I cant find complete course.

Thanks for your help

 

[chlaurite]

Does somebody know where can I read - how to recover gold from RAM fingers?

This thread involves depopulating (aka "removing the chips from") RAM sticks, presumably for pyrolysis-lite (sorry, in-joke, we have an ongoing debate on that one) on the chips themselves. Doing gold fingers takes a HECK of a lot less work than that, but still requires understanding far more than a simple tutorial.

To get started, though, use the search on this forum for "hoke". You can find (at least) two versions of her book as free PDFs (inline flow, and interleaved for printing 2-up) linked throughout the forum.

Then once you've gotten the basics from reading that book, come back and search for "acid peroxide process", including the quotes.

/ Side note to Harold - We should just have a "reference library" section of the forum, so we don't need to send folks off to search for the absolute basics, like Hoke. Just an idea for the future.

 

[rickbb]

Is this the same David that has thousands of kilos of gold bars he needs to have assayed and imported through Liverpool UK?