# Foil removal/collection cell



## aga

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.


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'.


The black pen marks are where i cut out the rim of each pot to form the 'wier'.


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.


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.


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.


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## g_axelsson

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


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## aga

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.


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## Topher_osAUrus

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


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## UncleBenBen

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...  :lol:


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## aga

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 :-


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## Topher_osAUrus

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.


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## Simon007

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


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## aga

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.


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## Topher_osAUrus

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.


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## FrugalRefiner

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


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## aga

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


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## FrugalRefiner

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


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## g_axelsson

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


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## aga

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.


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## UncleBenBen

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.


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## g_axelsson

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


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## anachronism

What Ben said. Worded so well.


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## g_axelsson

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

Göran


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## aga

Oh !  

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.


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## aga

g_axelsson said:


> ... gold dissolved in solder will be almost colloidal.


I was about to ask how you'd know if you had a colloidal solution, then remembered the laser trick.

Just shine a laser pointer through the liquid. 

If you can see the beam, there are particles in there.
If you can't see the beam, there are only dissolved atoms in there.



The Left hand tube contains some of vinegar/salt liquid which clearly has some particles in it that are not dissolved. Doesn't mean it's gold, just that there are particles of some kind.

The one on the right only has distilled water in it : no beam=no particles.

I think the theory goes that for something to scatter the laser beam, it has to be at least as big as the wavelength of the laser, or something like that.

This is a 532nm laser pointer, and a gold atom is 144pm in diameter = 0.144nm, so if this was a colloidal gold solution, the gold atom-clumps would be made up of at least around 3,700 atoms, probably less accounting for the space between them.

Just need 32,061,894,054,054,100,000,000 of those to make a 1 gramme ingot :lol:


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## anachronism

I like that trick. Thanks Aga.

Jon


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## aga

I forgot to mention that a laser pointer can blind you !

NEVER EVER look directly into the beam : always shine it straight down into the tube/cup and look at it from the side, at a distance.


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## anachronism

aga said:


> I forgot to mention that a laser pointer can blind you !
> 
> NEVER EVER look directly into the beam : always shine it straight down into the tube/cup and look at it from the side, at a distance.



Ok ok ok - yes we get the message don't go from one extreme to the other mate lol 

(haha that was funny)


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## Topher_osAUrus

Hah.

Thats a nice little trick aga, I knew it would work for determining tubidity of an AR solution with AgCl, but had no idea it was applicable for colloidal gold.

Thank you


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## chuckgambale

I often hear of the dangers of the acids that we work with and I think that at least most of us know those inherent dangers. I had my own drain cleaning business for some time and many of the acids and other chemicals are perfectly safe to dispose of. I also grew up in a small town in Massachusetts with a very big sewage treatment plant. Now both of this already said and please listen, it is the metals in solution that cause the biological issues for the marine life in sewage treatment plants. It is the metals in solution that cause all kinds of medical maladies from leaching into groundwater wells. If you use vinegar and salt to put copper in solution and you dump it down the drain because there is no dangerous acids you need to study way more. Maybe we should talk more about the dangers of metals in solution more or at least as much as the acid dangers.


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## chuckgambale

This is in no way reflected on the op I just hear how safe this vinegar leech is and cringe. Sorry if it felt like an attack


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## anachronism

chuckgambale said:


> This is in no way reflected on the op I just hear how safe this vinegar leech is and cringe. Sorry if it felt like an attack



Stating your opinion in a reasoned way is never an attack Chuck. You've every right to state your opinion sir. Too many snowflakes out there these days who don't like to hear a contrary viewpoint though! Don't apologise.

Jon


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## aga

Sorry to be going from one extreme to the other.

Still finding my feet in this forum, and am more than happy to take any guidance anyone has to offer.

People stating what is on their mind is not offensive to anyone with a brain behind their ears, so please do not be concerned.

Yes, heavy metals ARE lethal to many organisms, especially in an oxidised state, noteably aquatic life in the case of copper, so the vinegar/salt solution is NOT 100% safe in the sense that it can be put down the drain.

I only meant that it is safer to work with, but got the sense mixed up/unclear, which is why i edited those posts to remove the '100% safe' parts.

Quite often a new reader only reads the first few posts in a thread, so leaving the misleading information seemed wrong. 

Appologies if that has made this thread make less sense and i will not do that again (i.e. not post stupid and flippant comments like that).

I will devote some time to rendering the resulting liquid neutral and safe to dispose of, or better, re-use, then post the results here.

The temptation to go ahead and try to refine the miniscule amount of gold foils i have stripped so far grows each time i look at them in the collecting pot, so that series of experiments may happen quite soon.


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## aga

Topher_osAUrus said:


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


Converting the 56% agricultural grade nitric acid i have (which is tinted orange/brown, probably iron) to Pure nitric acid, i'd react the acid with something cheap, extract the crystals, dry them, then distill over conc sulphuric acid to get 99.9% pure nitric acid, then dilute that down to whatever is required.

Quite a lot of work really, plus lots of dangerous hot acids and NOx fumes.

Does it really matter if you have totally Pure acid in the refining process ?


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## Topher_osAUrus

aga said:


> Topher_osAUrus said:
> 
> 
> 
> Fuming nitric isnt necessary in any refining really, so you can save that for something else :twisted:
> 
> 
> 
> Converting the 56% agricultural grade nitric acid i have (which is tinted orange/brown, probably iron) to Pure nitric acid, i'd react the acid with something cheap, extract the crystals, dry them, then distill over conc sulphuric acid to get 99.9% pure nitric acid, then dilute that down to whatever is required.
> 
> Quite a lot of work really, plus lots of dangerous hot acids and NOx fumes.
> 
> Does it really matter if you have totally Pure acid in the refining process ?
Click to expand...


It may not be iron, but just NO2 gas, like the difference between red and white fuming nitric.

I think it would be fine for refining purposes to be honest, but there may be a contrary viewpoint another member may shed light on.


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## anachronism

If the sheet that comes with the 56% Nitric says it's 56% Nitric and doesn't mention contaminants then that's what it is. You should have that sheet with the delivery. 

The red/brown tinge that you mentioned is probably what Topher mentioned above. Was it delivered in an opaque container? If you think that's iron then you might want to do some further reading on Nitric acid and it's derivatives and by products. 

I wouldn't waste your time trying to distil it or make fuming Nitric. Not only does it serve no purpose but it's also horrendously dangerous in that form. Why do it?


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## FrugalRefiner

aga said:


> Converting the 56% agricultural grade nitric acid i have (which is tinted orange/brown, probably iron) to Pure nitric acid, i'd react the acid with something cheap, extract the crystals, dry them, then distill over conc sulphuric acid to get 99.9% pure nitric acid, then dilute that down to whatever is required.
> 
> Quite a lot of work really, plus lots of dangerous hot acids and NOx fumes.
> 
> Does it really matter if you have totally Pure acid in the refining process ?


No.

The orange/brown color may or may not be iron. When nitric is exposed to light, it can begin to break down into other NOx compounds, which we see as the BFRC. 

When you dissolve your gold it is rarely pure (otherwise, you probably wouldn't be dissolving it). We use selective reducing agents to precipitate the gold and leave the impurities in solution. A bit of iron shouldn't cause you a problem unless you're trying to produce ultra pure gold, like 4N+.

Dave


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## g_axelsson

You are hooked now... :mrgreen: 

Nice trick with the laser.

The reason I said "almost colloidal" was that the powder had a distinct purple tone and went straight through my filter paper but it settled finally. The purple color disappeared when I put it into AR.
Colloidal gold made from testing with stannous have a purple color and true colloidal gold solutions usually goes in red and purple depending on size of the particles.

To check for contaminants in nitric acid, just add some to an evaporating dish and let it evaporate. Anything left is what was dissolved in the nitric as contaminant.
Unless you are trying to make 99.999% pure gold a bit of iron or other contaminant in the nitric doesn't affect it much.
If you have palladium in the nitric (that would be a pleasant problem) it might contaminate the gold if you are using SMB (SO2) as precipitant, but then there are a couple of other precipitants to select from, iron sulfate, oxalic acid or ascorbic acid for example.

Göran


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## aga

This nitric acid was just 9 euros for about 5 gallons, plus 2 euros deposit on the container.

No paperwork comes with it as it is intended for farming use.
The brown is most likely Iron as this is probably a by-product of some other industrial process.
That can be tested here, so i will do so tomorrow and post the results.

Purifying it does carry a lot of Very Serious, potentially Lethal dangers, especially in the distillation step, so it is good to hear that might not be necessary, even though i'd make a max of about 100ml.

As a noob to gold refining, i assumed that the purer the reagents were, the purer the end result would be.
Probably another wrong assumption as ways must have been worked out over the years.

Having said that, without chemically pure reagents, how does one assay the end product's purity ?
Weight/density surely will not be enough to calculate down to 0.1%, or will it ?

I understand that there are some X-ray diffraction techniques, but i just do not have that kind of equipment.


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## Topher_osAUrus

I know the crystallization in the pipe on melted gold can give some guru's here a great idea on the golds purity (and even some impurities, i.e. Pd gives a fern crystallization pattern on the gold itself...copper makes the gold more orangish reddish, silver more green)

The colour of the precipitated powder can also give a bit of a clue, light tan is a good sign its high purity.
Color of the washing liquors is another indication.

Color of the borax after melting is one more.

But, as far as testing impurities at the home hobby level...
...um.. Got a buddy with an xrf? -far from *exact* but, can give a general idea.
Atomic absorption is another one, but, also outside the hobbyists level

I know there is more, but I cant recall at the moment.


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## g_axelsson

A good scale and fire assay can go quite far up in purity but at some limit it is hard to find out how much mass is missing. Then you can use spectroscopic methods and calculate the fineness by difference.

Here is a discussion that talks about a couple methods.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=41&t=24292&p=257445#p257445

For the amateur some visual cues goes far. No oxidation on the surface when melting a button, crystallization of the molten gold with a nice pipe and mirror like surface is all signs on good purity.

To get good purity you should wash the gold after it is precipitated to get rid of some contamination before melting. Don't forget cleaning your torch and use a clean melting dish.

Here are links to both Harolds and Lou's tips on cleaning the gold.
http://goldrefiningwiki.com/mediawiki/index.php/Washing_gold_powder

Check this post for a picture of Harold's breakfast bowl. :mrgreen: 
http://goldrefiningforum.com/phpBB3/viewtopic.php?p=3248#p3248

Göran


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## aga

Thanks for tips and links. So much to learn here !

As promised, the nitric was tested for Iron ions (Fe3+) and came out positive.
Not a huge amount present, but definitely there.



That was with diluted acid and a few drops of ammonium thiocyante solution.
If enough Iron ions were present, it would go intensely red, like blood.

P.S. very much enjoying Hoke's wonderful and practical book !


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## Topher_osAUrus

aga said:


> P.S. very much enjoying Hoke's wonderful and practical book !



She did write a couple books that were spectacular.

And that little amount of iron i dont think would cause you problems in your refining gold to standard purity.
Maybe if you try Lous crazy 6N purity method youd need nuch better acid...and water.


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## g_axelsson

aga said:


> P.S. very much enjoying Hoke's wonderful and practical book !


She wrote more than one book, links to downloading "Testing Precious Metals" is at the bottom of
http://goldrefiningwiki.com/mediawiki/index.php/Hoke

Göran


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## Topher_osAUrus

g_axelsson said:


> aga said:
> 
> 
> 
> P.S. very much enjoying Hoke's wonderful and practical book !
> 
> 
> 
> She wrote more than one book, links to downloading "Testing Precious Metals" is at the bottom of
> http://goldrefiningwiki.com/mediawiki/index.php/Hoke
> 
> Göran
Click to expand...


A little birdy told me, that one of these days we will be getting a new and improved scanned copy of her testing book..

..okay, it wasn't really a bird, it was Dave. 

But, that book is great in its own right, as it contains a good bit of useful information that her refining book doesnt have.
Like the tolerance laws on karat alloys, discerning iridio platinum and ruthenioplat (i think thats how she "termed" them)

And how to price gold when buying, etc..
Except she uses dwt and a 35$/ozt price point..

But still... Great book!... I think I'm in love with Mrs Hoke :wink:


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## aga

UncleBenBen said:


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



Very poorly as it turns out.

Although this idea is fun to try, it's pretty much junk compared to the more accepted and 'normal' routes of stripping, even at the hobby level.

Having had a glimpse of some shiny gold, there is no option now but to collect it all and proceed to the really fun part : my first refining, melt and ... maybe solid gold ! 
(maybe just more toxic waste to render safe)

Made some Stannous Chloride test solution, as per lazersteve's post here :-
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=41&t=5271#p45030

The remaining connectors are dissolving in a kind of AR solution. 
This is happening in a fume hood so that the NOx fumes are safely handled. 
Never knew the acids did not have to be highly concentrated for it to work.

A few drops of the SC solution on some filter paper dipped in the dissolving pot goes almost black immediately, so the stannous chloride test must be very sensitive.

The connectors looked hard to break up easily/effectively and have lots of small holes to trap things in, hence going straight to AR as it seemed simpler (at least to separate the plastic/metals).

This will certainly make a Nasty mess of a liquid with a tiny bit of chloroauric acid in it.

After this first crazed (yet fun) rush to get started, following a well-known and documented procedure will certainly be the best way to go.

For this first try, i'd really like to see first hand how a completely botched 'refining' turns out, particularly the appearance and colours of solutions/muds/metal blobs. Botched it will certainly be.

A second or third Proper refining will definitely be needed, but if i didn't like doing this kind of thing, i wouldn't be here !


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## g_axelsson

Stannous is really sensitive and can easily detect sub gram per liter solutions of gold. SO2 will give a false positive, but after a while you start to recognize the signs.

Be aware that some plastics break down in AR and creates a sticky mess, trapping the gold.

Göran


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## aga

Can't believe i messed about with salt 'n' vinegar.

A couple of hours in nitric works much better to lift foils from fingers.


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## FrugalRefiner

Is that a disposable plastic drinking cup you're running a nitric reaction in?

Dave


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## aga

Yep. [stt]PET plastic works fine for this kind of thing[/stt].
Edited: the cups turned out to be PP not PET.

HDPE would last a lot longer, probably.

Edit:
I have 3 1L versions of these laden with anywhere between 3 and 6g of gold between them, as i have no Large beakers yet.

For a bit of security they were placed inside another 1L cup.

So far so good (nothing leaked).

Edit days later: strikethrough incorrect PET statement.


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## FrugalRefiner

aga said:


> Yep. PET plastic works fine for this kind of thing.


No, it does not! Readers, do not rely on this advice!

First, PET does not stand up to nitric acid. You may have gotten lucky so far, but PET will soften and collapse.

Second, using things like beverage glasses for refining is a bad practice. All it takes is one careless moment to pick up a glass and take a drink.

Dave


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## aga

Personally i feel the rebuke unfounded, and i'm not offering advice, just saying/showing what i did.

Polyethylene plastics are impervious to water, which makes ionic reactions (such as happen in AR) very very slow indeed.

Concentrated Sulphuric, Nitric and Hydrochloric acids are routinely stored and shipped in HDPE (high density polyethylene) as is concentrated bleach (sodium hypochlorite).

This is because it reacts so very very slowly, and also retains it's mechanical strength for a very long time,. despite chemical attack and UV effects.

In any event, the Volume of solution i made required more than the available borosilicate 250ml beakers i have, so needs must.

The biggest downside to polyethylene versus 3.3 boro glass is that you can't heat it on a hotplate.
Heating it in a microwave oven works fine (that's what i did) although the oven will get corroded by the fumes.

One Bonus is that polyethylene will never shatter.


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## jimdoc

Reactions heat on their own.


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## aga

FrugalRefiner said:


> First, PET does not stand up to nitric acid. You may have gotten lucky so far, but PET will soften and collapse.


This is not a difficult experiment, yet you offer no data to support that statement.

I'm off on holiday next week, so tomorrow i will fill some cups with nitric, photograph them, then go and enjoy myself, come back, and photograph it all again a week later.

If i can find the rig, i'll do a tensile strength test on the 'before' and 'after' cups.

That's how Science works - just measure things before, test it, measure after, work out the difference(s).



jimdoc said:


> Reactions heat on their own.


Some do, some don't.

If you're ever stuck with Hot beer on a warm day, stick it in a bucket of hot water, add ammonium nitrate, wait a few minutes then enjoy cold beer.


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## FrugalRefiner

aga said:


> FrugalRefiner said:
> 
> 
> 
> First, PET does not stand up to nitric acid. You may have gotten lucky so far, but PET will soften and collapse.
> 
> 
> 
> This is not a difficult experiment, yet you offer no data to support that statement.
Click to expand...

Instead of experimenting, why don't you try a little research. I'll make it easy by attaching a chemical resistance chart. There are others scattered all over the forum and the internet.

HDPE is very different than PET.

Putting refining solutions in a drinking glass is foolish.

While you may not have advised anyone to do what you did, you showed a picture, then posted that it's just fine. I don't want anyone else getting hurt because they read this thread some day in the future and followed your example, so I think the rebuke is totally justified. If you feel I'm out of line, you're welcome to take up your concerns with another moderator or Noxx.

Dave


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## aga

Point taken : Safety First.

Appologies if my reply caused any offence - i respect your view as a Mod and would never challenge it via the back-door so to speak.

The manufacturer's chart doesn't say what '"resistant" actually means, and has the disclaimer "dependant on time, concentration, and temperature".

Certainly PET will leak and fall to bits if heated to about 240 C.

I'll do the simple experiments and find out exactly how resistant it is to HNO3 etc at common concentrations myself.

So far it has worked OK for me, although that is an un-scientific and subjective view.


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## snoman701

HDPE is polyethylene
PET is polyester (polyethylene teraphthalate)

The latter is readily, albeit slow, hydrolized by acidic (and moreso) basic solutions.

The prior, not so much.

Experiments are unnecessary, they've already been done and published. 

Organic compounds and concentrated acids should really should be by the book, especially if you dehydrate your waste products.


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## aga

snoman701 said:


> Experiments are unnecessary, they've already been done and published.


Would you happen to have a link to any published research on this ?

I've only found mechanical data, and chemical resistance descriptions such as 'Poor' and 'Good-Fair' - no actual facts.


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## snoman701

Just google it, polyester hydrolysis

Further though, appropriate labware is sturdy. You can get away with kitchenware that may not be completely resistant to acids, but it has to be sturdy.


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## kurtak

aga

Granted - a lot of the chems we use (acids included) come in plastic containers - but those containers are intended for ambient temp storage !!! 

When you start using plastic containers for "reactions" you are introducing a whole other set of circumstances - heat (from the reaction) being one as well as oxidation being another --- heat is going to cause the plastic to become soft (period) which can/will lead to potential collapse &/or rupture --- oxidation can/will lead to potential of actual chemical break down of the plastic & again collapse or rupture

I understand getting set up with "real" lab ware (beakers, flasks etc.) is an expensive investment for the beginner - BUT - you can use a variety of "old" kitchen ware that will work perfectly fine for the beginner & you can get it CHEAP from second hand stores &/or yard sales

old coffee pots are nothing but a beaker - they are just shaped different :!: 

Proceram can be used & it comes in many sizes & shapes including coffee pots :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=85&t=22043#p229317 

Also - they make a glass cooking ware called VISIONWARE - I buy all I can get my hands on (CHEAP) when I see it second hand stores &/or at yard sales --- like pyroceram it will hold up to the heat of incineration

:arrow: https://www.amazon.com/s/?ie=UTF8&keywords=visionware+cookware&tag=mh0b-20&index=aps&hvadid=4967918444&hvqmt=e&hvbmt=be&hvdev=c&ref=pd_sl_5v0w119ae3_e 

As far as reaction of nitric "only" - non-magnetic SS (Stainless Steel) works just fine --- I use 5 gallon SS pots for dissolving my silver all the time --- SS just wont hold up if chlorides are involved (like AR) but SS is perfectly fine for nitric "only" 

There are MANY better CHEAP options of better stuff out there to get you started RIGHT in this rather then going down a path that amounts to nothing more then a DISASTER WAITING TO HAPPEN :!: :!: :!: 

Consider your self LUCKY so far :!: :!: :!: 

Kurt


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## g_axelsson

aga said:


> snoman701 said:
> 
> 
> 
> Experiments are unnecessary, they've already been done and published.
> 
> 
> 
> Would you happen to have a link to any published research on this ?
> 
> I've only found mechanical data, and chemical resistance descriptions such as 'Poor' and 'Good-Fair' - no actual facts.
Click to expand...

https://www.google.se/search?q=pet+nitric+acid+compatibility&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=MLvCWJzNI-yO8QeE2bHgBg

According to the first hit : http://www.plasticseurope.org/Documents/Document/20100705182216-050303GeneralChemicalResistanceofPET-20050303-003-EN-v1.pdf


> Nitric acid <10% = PET exhibits good resistance to attack; chances of successful testing are very good.
> Nitric acid 10-20% = PET has marginal resistance to attack; significant chance of container failure.
> Nitric acid >20% = PET exhibits poor resistance to attack; should not be considered for this application.



Recommendations from manufacturers is also facts. Not everything have to be published research.

Göran


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## aga

Thanks very much for the link.

At the very top they clearly say (about the information):-
"... should not be construed as implying a legal guarantee for specific properties of the products or for their suitability for a particular application"

Unfortunately they do not state the actual application (e.g. rotor vanes, bulk container, reaction vessel) nor do they say what a 'significant chance' means, so at best it is a guideline, not fact.

This list has 2 ratings for each concentration, one at 20C the other at 50C, and explain some of their ratings :-
http://sevierlab.vet.cornell.edu/resources/Chemical-Resistance-Chart-Detail.pdf

Again there is no application-specific detail.

The experiments are very easy, so i'll establish the facts about the use of PET containers with the chemicals/materials used in e-scrap gold recovery myself.

Edit:
Oops. Setting up for the experiment i noticed the number in the recycling symbol was a 5 not a 1.

These are poly proplylene, which is much more resistant to acids and bases than PET.

Sorry for not checking that earlier


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## kurtak

aga said:


> The experiments are very easy, so i'll establish the facts about the use of PET containers with the chemicals/materials used in e-scrap gold recovery myself.



aga

I am not sure what you are trying to prove here (other then you are some sort of self proclaimed master mind) but it has already been stated by a number of us that have been members of this forum for "many" years (compared to your 2 - 3 month) AND that have been doing this MUCH longer then you & as well on a MUCH larger scale then you --- that using small thin walled plastic containers as reaction vessels - is NOT advisable &/or acceptable & should therefore be considered BAD advice NOT TO BE FOLLOWED 

Though you may get away with it on a small "experimental" level --- It is a DISASTER WAITING TO HAPPEN

aga

Having read other things posted by you - I see you like to be argumentative &/or defiant expressing your self as someone with a great deal of experience &/or knowledge when in fact it is clear you still have a GREAT deal to learn - one of which is that this BIG chip you have on your shoulder does NOT serve you well :!: 

In case you are not getting the picture aga - you have "stormed" into this house with little or no experience as if you own the place & are someone to recon with even to the point of being confrontational with "long standing" members that have MANY more years experience then you & experience on large scales you have yet to even dream of :!: 

You seem to a smart individual aga capable of learning & doing this - but as a word of good advise I suggest you get rid of this big chip you carry on your shoulder --- or you may find your welcome here short lived 

Kurt


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## aga

Thank you for taking the time to offer the detailed advice Kurt, and for defending this excellent forum.

1. I am not trying to prove anything to anyone else.

2. My experience at PM recovery/refining is still basically Zero (no metallic gold yet).

3. The combined Centuries of actual experience that the members here posess overshadows anything i might even imagine i know.

4. When someone says 'unsuitable' or 'gets warm' i automatically want to know 'why' as in what happens, and 'how warm' as in degrees C.

Re-reading some things i've said here, i agree with you about the chip-on-shoulder thing and will go and work out why that is.

Until i've completed the recover/refine/melt process i'll not post anything else.

Without even being able to show my first gold button, i don't really have any right or reason to be posting anything about any part of the process. Same as for any noob on this forum.

Apologies for any offences caused.

adrian.


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## Topher_osAUrus

That first link kurt posted, about the corning pyroceram. The first picture is NOT actually pyroceram.

It looks like an anchor knockoff, if its a "corning" it is from the years when they started doing the "stoneware" and put out a "new formula" of "pyroceram" but, it cannot hold up to being put on the stovetop still.

Corning pyroceram has a gorgeous white color thats unmistakable (unless of course you get the beige pyroceram)

The pyrex dish featured in that thread will suffer a terrible fate if subjected to uneven heating by flame or a burner.
Pyroceram is a far different beast than pyrex.


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## glorycloud

aga - it has everything to do with safety. Yours and ALL the readers of your post
that will SEE THE PICTURES and think that it's OK to do what you were doing
by using thin walled plastic containers to hold reactions with nitric acid.

I believe that was the reason for the vociferous (and rightly so) response
from the moderators and those who recognize the "potential" danger. I personally
look forward to the day you will post your first gold button. We will all congratulate
you!! I, however. would not want to read of you getting your first button after
experiencing an accident or self inflicted heath issue by cavalier usage of chemicals
that can so easily cause harm. 

Hang in there and stay safe mate!


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## kurtak

glorycloud said:


> aga - it has everything to do with safety. Yours and ALL the readers of your post
> that will SEE THE PICTURES and think that it's OK to do what you were doing
> by using thin walled plastic containers to hold reactions with nitric acid.
> 
> I believe that was the reason for the vociferous (and rightly so) response
> from the moderators and those who recognize the "potential" danger. I personally
> look forward to the day you will post your first gold button. We will all congratulate
> you!! I, however. would not want to read of you getting your first button after
> experiencing an accident or self inflicted heath issue by cavalier usage of chemicals
> that can so easily cause harm.
> 
> Hang in there and stay safe mate!



Correct :!: 



> Until i've completed the recover/refine/melt process i'll not post anything else.



Adrian

I know I came down on you rather harsh - but that was "only" because you tend to "press a point" even after being told (in a friendly manner) to chill out --- in "no way" was I telling you to stop posting - I was simply informing you that you need to "check" your attitude & because you seem to "not take heed" to our lighter approach - it seemed hash words were in order --- they were NOT meant as a personal attack :wink: 

SAFETY is our "Number One" concern on this forum - when we see someone (especially a new member) posting something that is mis-information &/or that pose's a potential danger &/or hazard it is our "responsibility" to address it & put an end to it --- in other words - when we address a matter for its concern of safety - its not open for debate &/or argument because its not just a discussion between you & us (us being the experienced members) but rather it is a discussion being viewed by "many" others - many of who are also new members

In short - we would not be doing our job if we allowed matters that concern the safety of members to be argued :!: 

So by all means - keep posting - just keep in mind you are still more of a student then a teacher & that as a student there is wisdom in paying heed to & showing respect for your teachers --- its the path to becoming a "respected" teacher yourself - & I believe you have that potential - you just need to chill out a bit :wink: 



> Apologies for any offences caused.



Apology excepted --- now take a "new" step forward & we will be looking forward to the first melted button of pure gold you produce 8)  

Kurt


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## aga

Don't get me wrong - i'm not offended or feeling sorry for myself at all, and i really do appreciate your words and warnings.

Just it will be better if i stop posting (especially when drunk) about stuff i have not even finished doing yet.

Tomorrow i'm off to India for a week, so if today's frantic efforts to get to button #1 fail, it'll be at least a week before i can try again.


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## salman1122

where is my post?


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## g_axelsson

salman1122 said:


> where is my post?


Which post? I deleted one in another thread three days ago when you double posted.

Maybe you forgot to press submit.

Göran


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## jimdoc

salman1122 said:


> where is my post?



All your posts can always be found here;

http://goldrefiningforum.com/phpBB3/search.php?author_id=53288&sr=posts

That link is from your profile page, where it says "Search user’s posts".

It also shows your latest double post.


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## g_axelsson

jimdoc said:


> salman1122 said:
> 
> 
> 
> where is my post?
> 
> 
> 
> 
> All your posts can always be found here;
> 
> http://goldrefiningforum.com/phpBB3/search.php?author_id=53288&sr=posts
> 
> That link is from your profile page, where it says "Search user’s posts".
> 
> It also shows your latest double post.
Click to expand...

Thanks for pointing that out, Jimdoc. Salman1122, I have deleted the post above as it was a double post. The other one is still where you posted it. Again, don't double post! It just creates extra job for us and spreads the answers in several places.

Göran


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