Tin and Gold alloy

[actionakash]

How do I separate gold from an alloy of Gold, Tin and Copper?
I am unable to recover the gold, require help please

 

[Lino1406]

Provided gold is in significant
proportion, you can use, among
others, aqua regia. Filter stannous
Dioxide, if any and then precipitate
gold selectively, with e.g. SMB.
If the proportion is not significant
you may need to concentrate
and get rid of excess HNO3.
Look for further information
in the forum threads

 

[goldsilverpro]

What are the approximate percentages of the gold, tin, and copper? In general, what is the source of this material?

 

[actionakash]

I have taken the pins of the computer connectors with gold polish and melted the metal mix to form an alloy. I have got the alloy tested and it shows 1% gold 29% tin and 70% copper. The tin seems to trouble me the most. I am unable to get rid of it.

 

[jimdoc]

I have taken the pins of the computer connectors with gold polish and melted the metal mix to form an alloy. I have got the alloy tested and it shows 1% gold 29% tin and 70% copper. The tin seems to trouble me the most. I am unable to get rid of it.

Melting it is your biggest problem.

Jim

 

[nickvc]

I have taken the pins of the computer connectors with gold polish and melted the metal mix to form an alloy

:shock:

That decision may haunt you for a long time, I hope you only melted a very small amount.
We try to eliminate base metals before trying to refine the values, especially those that are troublesome and tin comes top of that particular list that we normally encounter.
Pins can be stripped in the sulphuric cell, remove the gold plate, or the solder that I suspect is the origin of your tin can be removed with a hydrochloric treatment prior to been put into AP to remove the copper leaving the gold foils for refining.
If what you have is a small quantity I suggest you put it aside and do some studying here on the forum and don't melt anything else until your fully informed about the methods and processes that are known to work. Start with Hoke and the forum handbooks both available free as downloads off several members signature lines and pay Lazersteves site a visit and watch his excellent videos of various processes, you can buy these and worth every cent, and research further using the search function either on Steves site or here on the forum.

 

[glondor]

Melting was a bad idea.

 

[Geo]

remelt, pour into shot or cornflake, process in AP. you will be collecting the powder from this process. you cant really use a nitric containing process because of the tin. dissolve in AP and collect the powder and then refine.

let this be a lesson. never proceed with a process without knowing what to expect. study the process first until you think you understand it and then study it some more. experiment on small quantities until you get it right.

 

[Oz]

remelt, pour into shot or cornflake

There is no need to re-melt this and cast as shot or cornflake if it is truly an alloy of 1% gold, 29% tin, and 70% copper. HCl digestion will leave him with a very fine gold particulate that will need to be recovered from his solution with care however.

 

[Geo]

will that deal with the copper too?

 

[Oz]

will that deal with the copper too?

Sure will just like AP, just slower to start.

In this case I would opt for the slower digestion using just HCl as adding H2O2 will invariably put some gold into solution temporarily. A bad idea with tin chloride present (stannous chloride), as the colloidal gold it would make would be real pain to deal with and not have significant losses. As it is he may still lose some to that, but this minimizes it. The tin should have been removed from the pins while still just pins with solder.

 

[actionakash]

Thanks all for such a quick response.

Actually I have just melted 100 gms, which is a small portion

Special Thanks Nickvc,
I will try this, please indicate if my thought process is in the correct direction

1. react pins with H2SO4 to remove tin
2. Filter the solution
3. Residue is reacted with HNO3 + H2O2 to remove Cu
4. Filter
5. Residue is treated in Aqua Regia
6. ppt with SMB

 

[NoIdea]

How about electrolysis?

Deano

 

[butcher]

NoIdea,
Yes one way I would consider would be using copper sulfate and break the (melted pins) anode down to powders using electrolysis, and then treat the powder to remove tin and then copper is one possible way to process.

actionakash,
100grams, of which 70 grams of copper, 29 grams of tin, and 1 gram of gold, that is if the ratios stated is correct, no matter how you processed it would be a lot of work, It would not be easy, I really believe your not ready to process this 100 grams of melted pins, or any of the materials you have collected, you do not have enough understanding of the process or how to deal with these metals and solutions I agree with Nickvc, put this button up and label it your first mistake, forget about trying to get gold until you do some studying, that way you will not be making mistakes like this loosing your gold or making it much more difficult to get, trying to recover and refine gold without understanding the process’s is a great way to loose your gold.

Studying Hokes book and doing her getting acquainted experiments will give you an understanding of what you will be dealing with, then studying the forum you will see us discuss these reactions and the problems with metals in solutions and how to process different types of materials, in the safety section learn the dangers of the acids gases and metal salts your dealing with, also learn how to treat the waste you will be generating safely.

For the time you spend learning will pay you back in gold.
Trying to process gold without learning you might as well just throw your gold in the trashcan.

 

[Stowmaster]

I also have a certain amount of gold flakes from a tin acid. Weight 25 grams, the gold content of approximately 5%. What to do - I do not know.

 

[butcher]

Tin and gold are a problem to separate, as tin is a problem in the acids it oxidizes very easily, and does not dissolve well at all.
Here is something I might try to separate the gold from the tin, assuming it was just tin and gold and not other metals, melt pour shot and hammer the shot flat, roast the shot red hot.

If it was just mostly tin and a small amount of gold it may react to make stannous chloride with a colloidal gold in solution, in a reaction with heated HCl, your problem then becomes separating the colloidal gold from the acid solution, if kept very concentrated and acidic, filtering out most of the acid can be somewhat easier (although like a slow nightmare), a press filter would help some, then boiling the colloids with a little H2SO4 can help somewhat to break colloids, or evaporating the concentrated colloidal solution down to powders, and incinerating the washing the tin from the gold in boiling HCl.

The problem with tin is it oxidizes so easily in these acids, and really does not dissolve, is almost impossible to filter solutions, and in chloride solutions with gold it forms the colloidal gold purple of cassius (we see when testing for gold in solution with stannous chloride.

I might also try some of the shot in a cupel and an oxidizing flame from my torch to see how that might work.

or I may try to break it down to powders with electrolysis in a cooper sulfate cell and roast the powders to oxides the tin powder and wash the tin from the gold powders with boiling washes of HCl.