I have asked before about the separation of filings from silicon
carbide and other abrasives and got all the nasty chemical amswers.
I was wondering if there is a physical rather than chemical way to
separate the silver out of the filings mix. Such as panning or
washing? I notice that adding dish soap to a bowl of filings breaks
the surface tension and helps to let the things which float in the
water to fall, often the floating things hold onto silver. SI is
lighter than AG on the atomic chart but I don’t know about the
carbide part of the mix. It seems to me that panning would go a long
way to separation or sluicing somehow. What do you think?
Have you tried a magnet? Really strong magnets do wonders, if have
an old computer that you can dig around in there are a bunch of
really big ones in there.
Silver has a specific gravity of about 10 grams per cc and silicon
carbide has a specific gravity of about 3 so you potentially could
separate them by panning. The reason gold was easy to separate by
panning is that its specific gravity is about 19 so it is much denser
than the minerals in river sand which are all around a specific
gravity of 3 so much easier to separate by density.
Just a comment on “SI is lighter than AG on the atomic chart”.
While elemental silver is much more dense than elemental silicon
(10.49 g-cm-3 vs 2.33 g-cm-3), unfortunately the density of elements
doesn’t tend to always follow location on the periodic table. More
importantly, in this case, the density of elements often has little
or no bearing on the densities of compounds or alloys made from those
elements.
It would be extremely convenient if this were the case, but it is
not.
Thanks, James, I’ll try panning and also dropping the filings and
blowing through them, the silicon carbide seems to get blown out.
I’ll post on Orchid and let you know how my experiment goes.
I am just obsessing about sending the refiners an ingot rather than
filings and I would not use the ingot myself. I don’t cast in house.
I thought if there was a way to simply get most of the crap out of
the filing then I can know better what my return should be. Hoover
and Strong seems to turn around my ingots much faster than when I
send in filings or loose scrap.
Sam, I too like to forward clean material for refining but I don’t
spend an inordinate amount of time working on it. The first thing I
do is pass a strong magnet through the filings pile…several times.
That will remove any steel from saw blades, files etc. When it is
pretty clean I kind of push the pile around and the lint comes to the
surface which can then be picked out or blown out with gentle breath.
Now, for the Sic remains, I don’t worry about it. Put it into the
crucible and fire it up adding a bit of borax. The Sic will be
trapped in the flux and skimmed off. That gives a pretty clean ingot.
Cheers from Don in SOFL.
I am just obsessing about sending the refiners an ingot rather
than filings and I would not use the ingot myself. I don't cast in
house. I thought if there was a way to simply get most of the crap
out of the filing then I can know better what my return should be.
Just melt it, the non metallic crap will float to the top of the
melt and form a slag with the flux. The metallic junk and the few
things that will alloy in will not significantly affect your
refining. Though you refiner will appreciate it if you don’t send
too much iron in with your scrap as it can make their job a little
harder. But they are still only going to pay on the precious content
so not that big a deal.
I second Christine’s suggestion, the magnets out of a hard drive will
pick up silicon carbide grit. Previously I used a lesser magnet for
removing iron filings from the silver filings (a few grains of
silicon carbide would stick), and I relied on the melting flux to
trap the remainder of the silicon carbide in the slag. Since using a
super magnet all the silicon carbide is picked up and the melts are
much cleaner as a result. I find that a quantity of silver filings
are picked up along with the grit and tapping the magnet gently will
shake the silver out. Pick up, tap, and clean the magnet repeatedly
until the grit is all in the recycling bin.
If you have a strong magnet, whether it’s one you rescued from a hard
drive or it’s a new rare earth magnet, an easy way to keep the magnet
clean when using it to pick out magnetic particles from bench sweeps
is to put it in a plastic bag or wrap it with a single layer of thin
plastic. Then when you want to remove the trapped particles all you
have to do is to remove the magnet from the plastic or baggie.