Best way to refine sterling?

[thesillym]

Hi,

If you already melted the stuff and made flakes, i guess to avoid large quantities of metastannic and acid waste, I would recommend cupellation first and silver cell after. This way you will minimize the acid usage thus waste creation, and can get rid of the tin and lead as well.

Pete.

I’ve seen small cupels for sale, but I have hundreds of ounces to process. I saw a method of making cupels using dry Portland cement and forming by compression into a bowl shape. Will that work? Or another diy or source for cheap cupels of larger size?

 

[Yggdrasil]

I’ve seen small cupels for sale, but I have hundreds of ounces to process. I saw a method of making cupels using dry Portland cement and forming by compression into a bowl shape. Will that work? Or another diy or source for cheap cupels of larger size?

The Portland cupels work.
But you still need a suitable furnace for them.

 

[Martijn]

Hi,

If you already melted the stuff and made flakes, i guess to avoid large quantities of metastannic and acid waste, I would recommend cupellation first and silver cell after. This way you will minimize the acid usage thus waste creation, and can get rid of the tin and lead as well.

Pete.

Or the parkes process to get pm's out of the lead with zinc. Depending on the amount of lead.

 

[grainsofgold]

you should have done a HCl leach on the silver to get rid of the tin/lead before melting

Then a GOOD washing to get rid of the vast majority of the HCl leach used to rid the tin/lead

Then incineration to rid the traces of chlorides

Then ether dissolve the sterling with nitric - cement with copper to up grade the 925 silver (sterling) to (plus/minus) 998 silver - then melt/pour anodes to run in the silver cell --- or - pour anodes as 925 (sterling) & run direct in cell --- when running 925 direct in the cell you ether have to make your electrolyte with MUCH more silver dissolved in it to prevent co-depositing of copper - or change out the electrolyte more often to prevent copper co-depositing

If I understand correctly - lets say you are taking apart sterling knife handles and weighted candle holders and other table top goods that have tin/lead metal as a filler-

Keeping this material separate - what's the preferred steps in getting rid of the tin/lead ?

1. Apply low heat so that the molten tin/lead runs off the sterling shells ( heat to only melt the filler material )

2. Boil the the sterling shells with the residual tine/lead on them in HCL ? ideal temp and how long on the heat?

3. Boil clean in Distilled water

4. Low heat applied to the washed shells to drive off the chlorides

Thanks

GOG

 

[anarxi]

the top layer of silver is simply removed.
either by electrolysis in a solution of sodium sulfite.
or chemically in a solution of sulfuric acid and nitric acid.
proportion 95/5 respectively.
in addition, metastanic acid, B tin, when working with silver does not bring such inconveniences as when working with gold.
just more time for the chloride to settle, less filtration, more decantation.
to paraphrase the legendary Mark Twain :

The report of metastanic was an exaggeration.

 

[cejohnsonsr1]

Sreetips has a couple of videos from a couple of years ago showing how to prepare those kinds of Sterling items for recovery and refining.

 

[snoman701]

Have you done the math to determine how much acid waste you'll be making to refine all of that? Might motivate you to sell it outright and just trade it on bullion or casting grain. You'll lose less money.

 

[kurtak]

the top layer of silver is simply removed.
either by electrolysis in a solution of sodium sulfite.
or chemically in a solution of sulfuric acid and nitric acid.
proportion 95/5 respectively.

These are processes used for dealing with silver "plated" items

This thread is not about silver plated items - rather it is about actual sterling (923) silver items

The items in question are items made with a thin layer/sheet of sterling overlaying a lead/tin "filler" - such as knife handles &/or candle sick holders

The question was how to get rid of the lead/tin residue that is still stuck to the thin sterling silver sheet after melting away the "majority" of the lead/tin "inside" the "overlaying" sterling item

Kurt