Anyone know a good way to seperate Tin from Lead?

[Cryogaijin]

Greetings!

My reverse electroplating of holloware has been productive, and I am closing in on a full KG of silver to start off a silver cell with. (I have lots more holloware to deplate now that I've got the technique down)

The one issue I'm running into are the handles and spouts for the things I am deplating. They're mostly silverplated pewter, but I have no idea what pewter formulation they are. I suspect the older ones have lead in them. Now Tin is actually more useful for me than silver, but having lead as an impurity utterly ruins its utility. (I'm casting bronze axe heads. Any lead contamination makes them unusable.) So does anyone know a good technique for separating tin from lead that doesn't involve dissolving everything in expensive Nitric? Or somewhere for me to start researching?

Thanks!

 

[Stibnut]

I don't have any experience trying to do that, but I'll just throw out an idea. Perhaps you could dissolve the tin in hot concentrated HCl, then cool with ice and dilute it somewhat to drop out PbCl2, which is poorly soluble in cold water. The stannous chloride solution could then be reduced to the metal with a more active metal like zinc. Stannous chloride is susceptible to hydrolysis to an insoluble oxychloride salt if the HCl solution gets too dilute though, while lead becomes more soluble as HCl concentration goes up, so it might take some fine-tuning to get the HCl concentration right.

 

[Swissgoldrefiner]

You can use electrolyse...sulfuric acid as electrolyte.

 

[Geo]

Addition of sulfuric acid to a chloride or nitrate solution will precipitate insoluble lead sulfate. It will not effect tin or any precious metals in solution or it's eventual recovery. Electrorefining tin from an alloy of lead/tin is easy as long as the proportion of tin in the alloy is in the high 90% range. Low voltage, low wattage is best to stop the long "whiskers" of tin from growing and shorting the cell. HCl is used as the electrolyte.

Pewter is normally an alloy of tin and copper. It can contain lead if it's older pewter but newer stuff, 80's up, should be lead free.

 

[Cryogaijin]

Addition of sulfuric acid to a chloride or nitrate solution will precipitate insoluble lead sulfate. It will not effect tin or any precious metals in solution or it's eventual recovery. Electrorefining tin from an alloy of lead/tin is easy as long as the proportion of tin in the alloy is in the high 90% range. Low voltage, low wattage is best to stop the long "whiskers" of tin from growing and shorting the cell. HCl is used as the electrolyte.

Pewter is normally an alloy of tin and copper. It can contain lead if it's older pewter but newer stuff, 80's up, should be lead free.

Thanks. This is easy as I can always enquart more tin to get above that 90% range. I've found a good source for copper and tin, so adding in more tin to get good pure tin back is fine with me.