# It is possible to separate silver from tin by melting/smelting ?



## razvanflorin (Mar 19, 2019)

Hello !! i have a question.. It is possible to separate silver from tin (3.5% silver 96.5% tin) by melting or smelting ? if yes, please give me more details about the process


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## Lino1406 (Mar 19, 2019)

Leadless soldering flux - better to leave it for what it was designed for than losing money on separation (and then mixing it again since what will you do with all that tin?)


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## nickvc (Mar 20, 2019)

This is another application for the use of silver which economics make unviable, that reason also includes many plated items and it’s use in double and triple glazing glass, it always amazes me when silver has so many industrial uses for which there seems no other metal or material substitute that it’s price is so low making its recovery untenable.


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## anachronism (Mar 20, 2019)

It's not worth messing around with for those figures.


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## snoman701 (Mar 21, 2019)

razvanflorin said:


> Hello !! i have a question.. It is possible to separate silver from tin (3.5% silver 96.5% tin) by melting or smelting ? if yes, please give me more details about the process



How much do you have?


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## razvanflorin (Mar 21, 2019)

2 tons weekly


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## canedane (Mar 21, 2019)

When i melting old tin cups and candle light Sn for scrap bars the upper side contain mutch more Sn.
The bottom have a higher lead %, i guess it is because the higher gravity.
Perhaps if you melt it in a long pipe the silver % will be high enough in the bottom of the pipe to collect it for recovering?


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## snoman701 (Mar 21, 2019)

Just keep searching for the word solder. 

https://archive.org/stream/preciousmetalsre00unit/preciousmetalsre00unit_djvu.txt


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## snoman701 (Mar 21, 2019)

Thanks for reminding me that I've got a good amount of it...I'll have to play with it now.

https://www.911metallurgist.com/blog/wp-content/uploads/2015/02/Recovering-Gold-From-Scrap-Electronic-Solders.pdf


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## g_axelsson (Mar 21, 2019)

The tin is worth more than the silver. Any refining method that doesn't recover both tin and silver incures a major loss.

Two tons per week is a decent amount to work with. I would research electrolysis of the tin, leaving silver as a byproduct in the anode mud. It can then be refined in a second step.

Göran


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## snoman701 (Mar 21, 2019)

g_axelsson said:


> The tin is worth more than the silver. Any refining method that doesn't recover both tin and silver incures a major loss.
> 
> Two tons per week is a decent amount to work with. I would research electrolysis of the tin, leaving silver as a byproduct in the anode mud. It can then be refined in a second step.
> 
> Göran


Not with silver in it it’s not. 

Tin loses its value quickly once you add anything to it. Too hard to separate.

Electrolysis of tin is done in a salt bath at 450-559 deg c. 


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## g_axelsson (Mar 22, 2019)

snoman701 said:


> g_axelsson said:
> 
> 
> > The tin is worth more than the silver. Any refining method that doesn't recover both tin and silver incures a major loss.
> ...


What I meant to say was that when separated in it's fractions and refined, the tin fraction holds the largest value.

You can also use electrolysis of tin with HCl bath in smaller scale. Here is an article about refining lead free solder.
http://www.qip-journal.eu/index.php/ams/article/download/161/120 (DOI 10.12776/ams.v19i3.161)
Alkaline baths can also be used but you need higher temperature to run it. (Around 80 °C)

An article about a tin refinery using electrolytic refining, producing 400 tons of tin per month.
Mackey, T. S. (1969). The Electrolytic Tin Refining Plant at Texas City, Texas. JOM, 21(6), 32–43. doi:10.1007/bf03378890
(Use the sci-hub site for access to the article)

Göran


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## asacoleman11 (Apr 28, 2019)

Does anyone know of any hobbyist that is capable of refining roughly 60 kilos of electro-mechanical components with a silver contents within which have came from bombardier works in Doncaster which made the famous trains The Flying Scotsman and Mallard etc. Which was demolished a few years ago. Also, I have 50 kilos of various electrical contacts which came from various components from different sources from the 70’s and 80’s. I’m willing to give a reasonable percentage but these electrical contacts need to be further tested for gold/palladium etc. If we can both come to some satisfactory understanding regarding the silver and the electrical contacts I would be happy to go ahead with the process.


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## asacoleman11 (Apr 28, 2019)

These are the electrical contacts 









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## FrugalRefiner (Apr 28, 2019)

I could be wrong, but the first group of pictures look like silver plated copper I've worked with. It's easy to test them. Take a file and file a deep notch into a few of them and see if they're copper under the silver.

Dave


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## bcgold (Apr 28, 2019)

Experimental cell.


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## bcgold (Apr 29, 2019)

Excellent way to depopulate boards, I'm using a weak solution of hcl and well water, if your using the cell to clear the boards from chips let the boards soak in the electrolyte to get a good saturation of tin ions in the electrolyte before switching on the power supply.

As the tin ions are depleted from the electrolyte new ions are added from the solder on the boards when your electrolyte starts turning green this is an indication that the tin ions have neared depletion and your liquor is taking on chlorine.

Your boards can be stacked and do not have to make an electrical contact with the power supply, the boards are just used as a donor for the tin ion.

Those small surface mounted chips will be the first to come free.

Switch your power supply off for half an hour to allow more tin ions to enter the liquor, maybe remove boards that have completed to process then adding some fresh ones.

The chlorine will strip the gold from fingers etc. not sure if it is being precipitated into the cell slime's or going into the electrolyte.

Silver from the solder is left as cell slime's, a divided cell with a membrane would make harvesting easier. You may even get lucky and recover a bit of gold from the solder.

The large carbon rod is from a very old 1.5 volt dry cell from which I also harvested the manganese dioxide, stainless steel sheet if from a hard drive. And the power supply is from an old PC, I'm operating the cell at 12 volts DC.

For some off reason the silver component likes to gather around the positive electrode.

Work under a fume hood or outdoors.


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## bcgold (Apr 29, 2019)

So far I've harvested about one pound of tin and recovered 4.4 grams of cell slime's. Time to build a larger cell.


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## anachronism (Apr 30, 2019)

Thanks for sharing this. 8) 8) 

Jon


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## Yggdrasil (Apr 30, 2019)

I have to agree with Jon on that.
A new test project on the horizon I think.
Thanks a lot for sharing.


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## bcgold (Apr 30, 2019)

Before I had set up the test cell had put some ram sticks in a post with a dilute hcl leach after heating it up for half an hour set it aside to cool then overnight these crystals appeared.

Since the predominant species in the leach was tin, it would be safe to assume these are tin crystals.

A heated leach will hold more salts than a cold one will so by heating your electrolyte you will probably have better results replacing the tin ions as they're being plated out onto the cathode.

With the formation of crystals I knew the liquor was saturated and this is what lead me to set up the experimental cell.


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## bcgold (Apr 30, 2019)

Forgot to mention remove battery's, aluminum heat sinks then when pulling aluminum caps try to pull them leaving the legs behind ( electrodes ) leading inside the capacitor, as these might be silver.

Whatever the electrodes are made of they dissolve during electrolysis and go to slime's.


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## anachronism (Apr 30, 2019)

It's certainly got potential. If you're effectively taking the tin out of solution with electrolysis so you can load more into the solution without wasting the solution you are using then it sounds like something worth looking at. 

Jon


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## bcgold (Apr 30, 2019)

If you fail to maintain an equilibrium in your electrolyte it will eventually end up as a barren solution. When other species are present the use of the electrolyte is not infinite, it will eventually foul.

From time to time small additions of fresh acid are needed to maintain a supply of free acid.

In this parting operation ( tin / silver ) copper chloride is your enemy, thankfully the solder mask keeps this to a minimum.


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## bcgold (May 3, 2019)

Nicer tin deposit, with luck it just might peel off as a sheet.


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## bcgold (May 7, 2019)

From that first load of motherboards.


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## rickzeien (May 7, 2019)

Really nice. Can you post some pics of the cleaned boards and SMDs?

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## anachronism (May 7, 2019)

Can I ask how you are sure that this is Tin please?


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## bcgold (May 7, 2019)

anachronism said:


> Can I ask how you are sure that this is Tin please?



What I"m doing is a recovery, both the tin and silver will have to be re-refined.

Pure tin when you bend it, it will cry.

From the activity series of metals I have removed from the boards, battery's and aluminum on the next batch have removed the majority of iron.


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## bcgold (May 7, 2019)

This is turning out to be a real adventure, tin catches fire when you try to melt it. 

Downloaded Metallurgy of Tin from openlibrary.org, this clearly describes what is taking place when I tried to melt some of the recovered tin into a button.


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## FrugalRefiner (May 7, 2019)

Why would you be heating it to such a high temperature? Tin melts at 231.9°C (449.5°F).

Dave


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## lunker (Jul 2, 2019)

I have achieved the same results. When trying to melt the resulting metallic cement. It fumes with a white smoke and sublimates white. I’m not sure if you could add a carbon source and smelt it? At first I was under the impression it could be re melted at its normal melting point. I believe treating it as a tin ore might work. Economics of recovery??? But is a great way to recover mlcc off boards.


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