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How to separate silver swarf from aluminum swarf?


#1

Hi, I think I’ve put myself in a real pickle here. A few years ago
when I was first experimenting my CNC machine I had triedto flycut
off a silver ingot. I got a lot of silver shavings thatway, but back
then I neglected to sweep the aluminum outof the way, so I have
something like an ounce of mixedsilver and aluminum in about a 1:1
ratio. I understand aluminum has a lower melting point than
silver.Since aluminum is less dense will it float on top of the
silver,so I could pour it off? Or do I need to contact a refinery?
Thanks, Andrew Jonathan Fine


#2

Hi Andrew:

Off to the refiner with you. Heating it up will just cause the
aluminum to melt, and very quickly start alloying down the silver
into a royal mess.

You said there’s about half an ounce of Ag? That’s $15. Anything you
could do to try to separate it yourself would cost more than that.
Save it until you’ve got enough to do a normal refining run, and put
into a separate bag when you send in the rest of of your scrap. Make
sure they know what it is, and that there’s aluminum in it.

Regards,
Brian.


#3

I aquired some 30 yrs ago a silversmiths drawbench. At the plate end
it was thick with tallow from 100 yrs use. I scraped it all off and
seperated out all the metal particles some 8 oz. From that pickling
it in dilute battery acid I recoverd some 4 oz of silver. seperated
by colour.

Put you mix into a solution of flowers of sulphur, the silver will go
black, the ali wont.

Dry, put on some white paper and pick out the silver with tweezers.
Still worth doing on principle.


#4

Hello Andrew,

Use soda (natriumcarbonate) which solve the aluminum easely in water
leaving the silver untouched.

Poor it of and rinse the silver…done. Hydrochloricacid will do
the same. I’m sure that others with more chemistry knowledge can give
you more detailed advice. In all cases, think smart and think save!

Enjoy and have fun
Pedro


#5

An ounce of pure silver is worth about $32 today. How much trouble is
that worth? Silver contaminated with aluminum is going to be nothing
but trouble for a craftsman. A refiner can set it straight, but if
you only have an ounce or two, the value will not cover the cost of
refining. If you expect that eventually you will have more material
to refine, save it. If not you may as well just give it to some other
craftsman who sends material in for refining now and then.


#6

Go to the hardware store and buy some hydrochloric acid, which might
be called muriatic acid and sometimes it’s “concrete etch”. Put your
metal in a glass container and generously cover it with the acid.
Leave it overnight and in the morning it will all be silver.


#7

Aluminium dissolves well in sodium hydroxide, commonly called caustic
soda. Commonly sold as a drain cleaner and probaly more readily
available than acid.

Nick Royall


#8

Safest thing send it to the refiner.

This is a dangerous procedure but lye in water will dissolve the
aluminum and not touch the silver. Lye will instantly blind you if
you get it in your eyes and cause severe chemical burns if it gets on
your skin. Wear goggles gloves etc and do it outside.

James Binnion
James Binnion Metal Arts