Antique tea tins

[GAGAU123]

Hi

I have some tins that seem to be plated gold inside.. the tins are badly rusted already and dented..

Pardon my impatience, but I don't seem to find anything dealing with these tins specifically.. my guess is it's because they are all long gone...

What is the recommended way to recover the gold.. it seems to iron.. plated with silver then plated with gold, I am still a total newcomer so I haven't even acquired the chemicals or reagents to test it.. it does seem real to me..

I'm also detecting old WWII items, and I found out that a lot of my horribly rusted smashed and busted coat buttons used to be gold guilded.. Unlike most other finds there's no visible gold on mine.. But I undid the button to see the insides and the parts that was protected by the "cap" of the pressed button, is nice and gold gleeming, even the insides of the button has some guild but not as thick as the outside.. What should I use to refine old brass and bronze for gold in this situation?

Is there a recommended method of swabbing the external surfaces with something instead of dissolving everything?

I have another burning question.. Electro-winning copper seems to have been implemented at the same time as the war.. What is the likelihood that you could clean antique copper and perhaps find some parts of gold or something? My gut tells me that back then.. chemistry was all everyone did, they had no TV's so they would probably have done a real good job at cleaning copper for brass and bronze alloy. If only they weren't as stingy back then and there's this surprize range of coppers you could refine for 1/200 parts or something.. you'd see metal detectives going banannas.. ;-)

Thank you, and sorry for any frustration.

 

[butcher]

GAGAU123,
Hi, and welcome to the forum.

I do not know if I can be of much help but I will try.

A picture would give us more of an idea of what material you are talking about.
I have some tins that seem to be plated gold inside.. the tins are badly rusted already and dented.

Tin becomes a problem in any solution, more so with nitric acid than with concentrated chloride solutions, We never wish to put gold and tin into solution together the tin will rob you of your gold, locking the gold up into the solution...

If the cans are iron you can dissolve the iron, there are several leaches that will dissolve iron into the solution but will not dissolve the gold, if much tin is involved in an alloy or plating the tin becomes a problem for nitric acid (metastannic acid gel), iron will dissolve in dilute nitric acid slowly.
Fe + 4 HNO3 → Fe(NO3)3) + NO + 2H2O
Concentrated nitric acid the iron will oxidize passivate and will not dissolve much at all - a small amount of Fe2O3 rust is formed and it coats the iron metal protecting it from the acid, the Fe2O3 rust coating that cannot be oxidized any further and the reaction then stops.

Copper (II) Chloride will leach copper iron and tin into solution if concentrated the tin will stay in solution with iron copper and other base metals.

Ferric chloride will also dissolve metals like copper iron and the other base metals, if concentrated and hot it becomes an effective silver etching solution (that will dissolve silver forming silver chloride).



What is the recommended way to recover the gold?
Normally we concentrate the gold, removing all of the other materials from the gold, the rock gangue material... after concentrating we may need some pretreatments like maybe roasting to remove unwanted materials or oils or to convert a metal salt to an oxide, (like converting sulfides to oxides in ores), we may then dissolve away the base metal and unwanted metal oxides, leaving us gold as pure as possible that we can then dissolve and refine it to a higher purity, we may even refine the gold again a second time for a higher purity of gold.

Each material ore or scrap is different and may need a different recovery process, often we will need to separate the different types of scrap from each other and process them differently, of separate from each other, same as we may need a different process of preparation to recover gold from an oxidized low sulfide ore deposit exposed on the surface leached by weathering of the mine than we would need with the same ore material found deeper underground in the mine of high sulfide deposits...

What should I use to refine old brass and bronze for gold in this situation?

Brass is made with zinc, bronze is made with tin (remember the problems with tin).

Is there a recommended method of swabbing the external surfaces with something instead of dissolving everything?
No, not really.
But sometimes we can have a situation where the base metal or unwanted metal will passivate in a solution, and we can then dissolve a more valuable target metal.

Electrolytically refined copper is pretty pure copper used in pipes and wire, no matter how old.

Now if you are interested in learning more you can use some of the words here, copy and paste them into our forum search, and you will find tons more information, that will answer your questions better than I can, you will also find answers to question you, or I would not even think about asking, you will also find clues of how to find out where the gold hides...

 

[GAGAU123]

The tins are somewhat like this.. I think the convention of calling them tins could be misleading..
However the primary plating beneath the gold could be tin..



The gilded buttons is brass...
They used to be perfect looking guilded back and front.. but you get varied amounts of aged damage..


metal-detecting they are more often smashed or stepped on or torn.. the good ones we keep but you could end up with a fair amount of scrappy ones.


As you can see with the designs of these buttons the button dome shape shell has a fair amount of lip folding over the base.. If you pry off this shell you can confirm that it was gilded.. It reveals a nice rim of protected guild.. the base definitely also had guild on it. Some of them looks like they could have had guiding on the inside.

"Electrolytically refined copper is pretty pure copper used in pipes and wire, no matter how old."
Even 120 year old copper wire? Sorry..

Thank you for the feedback..

 

[g_axelsson]

"Electrolytically refined copper is pretty pure copper used in pipes and wire, no matter how old."
Even 120 year old copper wire? Sorry..

Thank you for the feedback..

Yes, even 120 year old wire definitely were electrorefined.
https://en.wikipedia.org/wiki/Electrowinning#History

The first commercial plants are 150 years old and electrorefining of copper paid for itself in both a better product and in the recovery of gold. If my memory serves me well, it only took about 20 years until almost all primary copper were refined.

Göran

 

[butcher]

I would think the military buttons and tin snuff cans would hold more value as they are.

 

[GAGAU123]

I'm going to try a little piece of each in a small vial to see what happens..

Is there any nasty things regarding existing brass\copper rust when dissolving?
I'm going to try ferric chloride.

 

[butcher]

If the ferric chloride is hot and concentrated, there may be some acidic chloride fumes so you will need to work outdoors or under a fume hood, and not work in your house or garage.