Correction below---changed word from along to alone. Sorry bout that.
Second paragraph, first sentence.


"Harold & Susan Vordos" wrote in message
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"Ignoramus6092" wrote in message
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On 2012-01-22, Jon Elson wrote:
Ignoramus6092 wrote:

I have a couple of medium voltage switchgear contacts, with seemingly
silver buttons brazed to them. I have a little heat treating oven. How
can I use it to unbraze the buttons, to what temperature should I set
it?
Man! Without knowing a bunch about the silver alloy and the brazing
alloy, it is pretty hard to know what would be the magic temperature.
If you had a barrel of them, you could do a couple tests to find
the temp.

I only have two, I would say I can make 1-1.5 ounce of silver from the
contacts.

i
Some things you need to know.

Some silver contacts contain cadmium. If the contact does not, the
solder may. Don't do anything with them without a breeze coming from the
side, to carry fumes away from you.

Some silver contacts are not silver alone, but sintered tungsten, filled
with silver. They will have a waffle pattern on the back side, obvious
when you remove the contact from the buss. The silver can be leached by
prolonged heating in distilled water and nitric acid. Keep the container
(beaker) covered with a watch glass to prevent losses of values.

Contacts are easily removed by heating with a torch. I've done, literally,
hundreds of pounds of them through my many years of refining precious
metals. Want to get them off easily? Hold the buss with a pliers,
while heating the contact. Apply heat directly on top, and keep watch on
the solder, below. When you see it's molten, rap the buss on the edge of
a coffee can. That dislodges the contact and the bulk of the solder, both
of which will end up in the coffee can. Done.

Don't toss the silver with the base metal. Silver is now over $30 troy
ounce.

Harold