Foil removal/collection cell

Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

aga

Well-known member
Supporting Member
Joined
Dec 28, 2016
Messages
258
Location
Spain
Not sure if this is the right place for noobs to post. If not, please advise.

UncleBenBen's beautiful photo has gotten me hooked on gold refining !

It will take a long long time to collect enough e-scrap gold to end up with anything like a gram, never mind an ounce, so i decided to build a cell to strip and collect gold foils as/when i find them. Foils will be much smaller to store than a big pile of PCBs !

The idea is to use 8% white vinegar and table salt with an aquarium bubbler to dissolve the copper under the foils, then use the 'wier effect' to collect the foils in a small pot.
schematic.JPG
The trick is to get the liquid level to be just under the lip of the collection cup. The rising bubbles kind of push the foils over the 'wier' at the top of the pot.

This was built using a 5L water jug and 6 disposable plastic cups out of the bin. Turns out that all of these can be shaped and welded together with just a knife and a soldering iron. This is 3 cups welded/shaped/have holes poked in them, all with a soldering iron, to form the 'Stripping Cell' and 'Bubbler Chamber'.
cupfits.JPG
The black pen marks are where i cut out the rim of each pot to form the 'wier'.
cuprig.JPG
With the pump on, air bubbles up through the stripping pot, (slowly) dissolves the copper and frees the foils, which get carried upwards by the bubbles and eventually spill over into the collection pot where they settle and cannot escape1. Any that do escape are caught in the outer container. If they are stirred up, eventually they get sucked into the liquid inlet to the bubbler chamber and carried back up towards the collection pot.
running2.JPG
After a couple of days, most of the foils have been stripped and wound up in the pot.
The solution is a nice blue from the dissolved copper.
collection.JPG
Besides being very cheap and easy, this rig takes up very little space and smells only faintly of vinegar.

1 the foils can all get out of the collection pot if cap'n bumblefuk picks up, then drops the pot, like i did, twice.
 
Nice design and thanks for sharing. :)

You will run into gold flash some day and pieces where the gold has been soldered onto. The gold flash will break down into tiny flakes and the gold dissolved in solder will be almost colloidal. This will probably end up as a dark sludge on the bottom of the large container. Even if it doesn't look like gold it can contain quite a lot of gold.

My last refine was the pins and fiber bodies from pentium mmx CPU:s (black fiber). A lot of the gold were in the form of a black to purple sludge after the pins and solder were dissolved.

Göran
 
At the moment it's all i got to share in return what what you guys are sharing !

Well, apart from about a nanogram of gold foils ...

While i expected the sludges to contain some gold, i never knew it could be significant, nor that gold can dissolve in tin/lead solder.

That's the second and third possibly vital bits of info i've learned here already.

First was to have a Lot more respect for people with years of experience in the gold refining game.
 
I like it.
Very clever.

Im sure you yourself have already thought of ways to improve thw design.
But, if I may ask, why have you opted for vinegar instead of HCl/h2o2 -aka copper (II) chloride process?
It is very easy to rejuvenate and is a good set and forget process.

Im not against the vinegar in anyway shape or form, and have read your posts on it at sciencemadness forums. I just think the copper chloride process may be more beneficial as the majority of the remnants are gold (unless the acid is exhausted, then copper I chloride) and with the vinegar, Im not sure how much of the copper salts will stay in solution over an extended leech cycle (say pounds and pounds of boards)

Interesting still, to say the least..
Thanks for sharing

-toph
 
Nice rig aga! Very clever.

It can take up a lot of time to recover PMs from escrap especially working at the hobbyist level. You get faster and more efficient as you learn. But if you enjoy tearing stuff apart as much as I do, then the gold is just a nice bonus! :lol:

I'd like to see if if your kit would work as well with plated pins!

aga said:
UncleBenBen's beautiful photo has gotten me hooked on gold refining !

UncleBenBen...The gateway drug... :p :lol:
 
Topher_osAUrus said:
why have you opted for vinegar instead of HCl/h2o2 -aka copper (II) chloride process?
Ummm. It is a Copper (II) process ...

Basically H2O2 is not available here (Europe) in anything other than 3% concentration, although 20% HCl is cheap in the supermarket.

As this will be a long-term thing, used only when i encounter more gold-bearing e-scrap, all the H2O2 would have decomposed to water and oxygen long before i finish finding enough gold, whereas the salt and vinegar will hang around much much longer.

In a commercial setting this would not work at all due to the Time required to do even a small amount of stripping, and HCl/H2O2 would be much better/faster, as would other methods.

It is also a little bit safer than strong mineral acids, although the resulting Blue liquid is still toxic and should be disposed of properly (not down the drain).

UncleBenBen said:
I'd like to see if if your kit would work as well with plated pins!
So, the Devil Himself speaks once again, luring unsuspecting noobs into Gold Fever with his gorgeous photos of shiny metal ... ;)

Too slow though : today i took a blowtorch to the PC main board and ripped off everything that so much as glinted and threw it in the stripping pot.

We'll see if it can rip the plating off all (or any!) CPU and connector pins in a couple of days.

As a side note, for anyone thinking this is about my own Safety, i'm not concerned about making/using 99.9% nitric acid if needed, nor handling any fumes generated, just that this vinegar & salt method works, is quicker and easier to get started for a noob, and is more accessible to any other noob who needs an easy way 'in'.

I live in the middle of nowhere, the Lab is well away from the house, got in-date A1 filter gas masks, full-face shields, fire extinguishers, and a fast escape route in case of total disaster (run out into the field, maybe jump into the pool as happened once)

Here's the home-made chemistry fume hood :-

hood.JPG
 
Fuming nitric isnt necessary in any refining really, so you can save that for something else :twisted:

And in the AP just a little but of peroxide (3%) is used to kick start the leech, then a bubbler is used to keep it working.
So its the same principle.

And 20% HCl would be perfectly fine in it too, as some water their ap down a bit.

Lazersteve has a very good copper II chloride leeching document on his website goldrecovery.us

Check his site out, very good place to find alot of great information.
 
Hi aga, where in Europe are you? It's just that I'm in England and can get 5L of 12% hydrogen peroxide on eBay for £11.75 and free delivery.


Sent from my iPad using Tapatalk
 
Topher_osAUrus said:
And 20% HCl would be perfectly fine in it too, as some water their ap down a bit.
Thanks for the information.

I do not know that 'ap' means. aqua propia ? (my water ;) )

I was born in the UK and live in Spain, inland on the Costa del Sol.
 
Forgive me aga,
AP is acid peroxide (bit of a misnomer, as it is really the copper (II) chloride thats the work horse)

-i forgot to mention, that too strong of peroxide or too much of it, will dissolve gold. Although in very small amounts, and if the solution is used repeatedly, it will cement itself out on the base metals and end up as more black sludge.
 
aga said:
It is also 100% safe, so i can leave it outside if needed and not worry if one of the dogs takes a drink !
Please don't believe that!! Both copper chloride and copper acetate are poisonous. If your dogs take a drink, they will probably die.

Dave
 
Agreed, with all chemical processes, best to keep Life and Chemistry as far apart as possible.

P.S. Some chemicals are So Crazy Toxic that they should never have been made in the first place.
https://en.wikipedia.org/wiki/Karen_Wetterhahn
 
aga, you can try to rationalize it any way you want, but your statement was just plain wrong. I understand you have some chemistry background, but many who come to this forum do not. Making a statement that something is "100% safe" is reckless and can put others in danger. Please, do not post things like that here!

Dave
 
I don't like the name AP (Acid Peroxide) as it isn't describing the process accurately. The roots of the name and the process is in circuit board etching by amateurs, using a mixture of hydrochloric acid and hydrogen peroxide. The name got shortened to acid Peroxide and then to AP.
I have made it into my mission here on the board to always talk about copper chloride process and not about acid peroxide.

The copper chloride process is a bit catalytic :
1. Etch : CuCl2 + Cu -> 2 CuCl
2. Regeneration : 4CuCl + 4HCl + O2 -> 4CuCl2+ 2H2O
A quirk is that CuCl isn't very soluble in water, but in strong HCl it is. HCl is also a perfect source of Cl ions for the regeneration stage.

Bubbling oxygen through the solution is all you need and there is no need for H2O2.

Among circuit board manufacturers the copper chloride etch is very popular, but there it is more common to use ammonia as solvent and it goes under the name ammoniacal copper etch.

Another way of kick starting the copper chloride process is to take a piece of copper, heat it with a torch for a while and then put it in HCl, copper chloride is created from HCl and the copper oxide that formed. Copper oxide is dissolved by HCl. Even easier is to put the circuit boards into the HCl and just wait, the dissolved oxygen will oxidize some copper and in a week the process is on it's way. Then you can use the copper chloride for the next batch.
I haven't used hydrogen peroxide to start a batch for the last ten years.

What I use hydrogen peroxide for is sometimes to dissolve fine gold after I have precipitated it from a dirty solution and it came down as a fine black ink, impossible to filter or wash properly. Then it is possible to precipitate it again, but this time a lot cleaner.
I prefer it over bleach since it doesn't add anything that isn't easily evaporated off.

Göran
 
FrugalRefiner said:
your statement was just plain wrong. I understand you have some chemistry background, but many who come to this forum do not. Making a statement that something is "100% safe" is reckless and can put others in danger. Please, do not post things like that here!

Mindless people wandering the 'tinterwebs and Believing everything they read are vulnerable, so i accept your reasoning and advice and will edit my earlier post.

Catering for the Safety of Unknown Others is a big pain in the ass.

For the record (if there is one) i'm just an Amateur Chemist and not a very good/very experienced one. No Phd etc.
 
Does the vinegar and table salt react to give some HCl? Something like:
2CH3OOH+2NaCl=2NaCO2+2HCl+3H2

And I'm no chemist what so ever, but isn't this just a weak form of the Copper(II)Chloride leach we have always used? If so then yes it's just a dangerous to all life forms.

Aga, I think you've got a lot to offer. You have to understand that most who come to the forum are already blinded by gold fever. Many are already trying to process with no real understanding of the dangers involved. It's hard enough to reason with folks in that mindset. People have died, and will die trying to recover gold. Thats a fact. That's why even the slightest of a lax attitude toward these dangers have to be addressed. And rightly so.

Catering to the safety of those headstrong new members is something everyone here feels a certain responsibility towards. You will see this over and over as you read through the forum and see how many people put themselves into very hairy situations. It's just part of what makes this forum so great is that the people here do care enough to try and keep everyone safe.
 
Well... claiming a process is 100% safe. You are producing copper acetate.

In http://www.unitednuclear.com/msdscopperacetate.html
Ingestion: May cause burning pain in the mouth, esophagus, and stomach. Hemorrhagic gastritis, nausea, vomiting, abdominal pain, metallic taste, and diarrhea may occur. If vomiting does not occur immediately systemic copper poisoning may occur. Symptoms may include capillary damage, headache, cold sweat, weak pulse, kidney and liver damage, central nervous excitation followed by depression, jaundice, convulsions, blood effects, paralysis and coma. Death may occur from shock or renal failure.

To claim that it is 100% safe also makes people think it is okay to flush down the drain, but the copper can easily knock out biological filtering in water treatment plants or leak into groundwater if it is dumped locally.

LD50 oral rat : 710 mg/kg is roughly saying an 80 kilo man has a 50% chance of survival after ingesting 50 grams.
To be fair, copper ions have such a horrid taste that the normal response is to vomit so lethal copper poisoning is really rare. That doesn't protect aquatic life though.

I recommend you to study waste treatment instructions here on the forum.

Don't take this personally, we get all types of individuals and we take a pride in always point out errors in the information here. Especially when it can result in damage to people, nature and property.

Göran
 
I forgot to add, nice fume hood!
Is it a shelf made out of tubes to the right?

Göran
 
Oh ! :oops:

Now i see what you all mean - don't post words that might lead others to take stupid risks, as they might take it as Gospel without doing the research.

Sorry. I'll edit out all/any relevant bits in my posts above.

The tubes at the right are just lengths of plain drainpipe angled at about 30 degrees with a chunk of polystyrene at the bottom.

They store all the Long glassware like condensers, burettes etc.
 
Back
Top