Assay a few contacts to figure out how much silver and copper you have,
figure out the $$ value of each if the 2 were separated, see how much
it would cost to do so, compare the resulting 'profit' to the
mixed-content salvage cost.
There's gotta be ways to sep. silver from copper. They might be
expensive in time or money or both, though.
Sure. The cyanide process will work, not sure it is worth the
hazards, unless you have 55 gal drums of the stuff.
I'm doing cyanide recovery of electronic gold scrap. I did a
trial run with moderate success, I think I have the chemistry
down and am setting up some gear to mechanize the process so I
don't have to babysit it so intensively.
Unless the Hunt brothers pull another silver swindle, I don't
think silver is worth the effort to do in house. Just sell the
scrap to a refiner.
It's not that simple. There are various compositions of contacts----a few
won't represent the average. Depending on the source, it could be very
You are totally misinformed. Cyanide reacts with copper almost equally as
it does with silver or gold. It is not a recovery process that works
economically. It hardly works at all. Silver is recovered from copper
either mechanically of with nitric acid.
Your moderate success is due in part to a nickel barrier under gold. Without
that barrier, you won't have good results. If you are not using a buffered
cyanide solution, your success will be less than desirable.
There is a sulfuric acid process that will recover gold and silver from
copper alloy with virtually 100% success, but it involves a water cooled
cell and high amperage. No ferrous based items can be introduced. That's
where the cyanide process shines----such as removing gold plating from watch
bands, although many of them have top caps that are copper alloy.
All depends on what you call "worth the effort". If one has a supply of
copper bars that have silver contacts attached, removing the contacts and
extracting the values can be very profitable, indeed. It all depends on how
much work you're willing to do, and how much you think your time is worth.
Dealing with refiners tends to be a losing proposition------something I know
from several experiences. Their fees often exceed the value of the precious
metals involved. I won't go into their honesty, which is often suspect.
Again, I speak from experience.
Do keep in mind that silver contacts are almost never pure silver. Many of
them are a composite of tungsten and silver, making them weigh far more than
their content in silver. They are also not easily refined, requiring a
long boil in nitric acid and water.
I'm not sure I've ever seen anything quite like you describe. The contacts
I've experienced (thousands of troy ounces, maybe tens of thousands of troy
ounces---I kept no records) are typically silver composition soldered to
pure copper buss bar-----and on many occasions silver plated after assembly.
It's fairly rare to find copper contacts----especially for high amperage.
Can you tell me how you've determined that yours are copper? If you'd
like to send me a picture, feel free----but please keep in mind I'm on a
dialup that connects almost routinely @ 26,400 bps. Please make the
picture reasonable in size.
Harold, the contacts that I have are from high voltage high power
switchgear and were mostly made by Allis Chalmers. They externally
look just like old silver would, shiny with blackish spots on them.
I took one such contact and ground it with a bench grinder a little
bit. Inside, a more yellowish/reddish material was seen, which I
surmise is copper.
I will try to look much more closely tonight and will try to determine
the thickness of silver layer. Maybe I could use a micrometer to gauge
the initial thickness, and the thickness just barely after outer
silver has been removed.
I surely can make pictures. I will not show them to the scrap dealers
that are coming tonight.
20 years ago I took classes in smithing and casting and got a great deal on
a 3" x 12" x 1/8" fine silver sheet. ($25) I've been using it for contacts
since. It seems to me that it is VASTLY superior than the stuff the OEMs
used. What's the advantage to the various alloys? Why don't they just use
fine silver for everything? I realize that my stuff is light duty, low
impact, low heat and low amps...did I just answer my own questions?
Great timing! That would be after silver hit an all time high of about
$50/ounce, then fell back drastically. Today, you'd expect to pay no less
than about $25/ounce.
Are you sure it's fine? It's not commonly used for jewelry, although not
unheard of. I'd think it was sterling---92.5% silver, 7.5% copper.
Great conductor, but not necessarily the best for arc resistance. Either
way, you did good. There's a simple test to see if you have fine silver, if
you have any doubts. A tiny drop of nitric acid and distilled water (don't
use tap water----it has chlorine in it) applied to the material will
dissolve a minute amount of the material and yield a clear solution that
precipitates silver chloride (looks sort of like cottage cheese) when you
add chlorine (table salt or HCL). If the solution remains clean, never
turns blue/green, it's pure. If you slowly develop a greenish color, which
turns blue after you're precipitated the silver, it's either sterling or
Could be, but not because they can't do better. It's long been a theory
about planned obsolescence. They expect you to buy replacement parts---which
I can imagine is a large part of their business. Replacement parts are
often priced thousands of a percent higher than their real cost. It could
also be that the contacts you replace are like the ones I'll describe below,
an alloy of silver and cadmium near as I could tell.
What's the advantage to the various alloys? Why don't they just use
I'm not a chemist, physicist or metallurgist, so I hesitate to reply, but
for one, silver is quite soft. That's the reason it was alloyed with copper
(10%) for coinage in our country. The combined elements are much tougher
than either one alone------much like bronze.
Don't short change the idea that it's far more expensive than base metals,
so they can stretch it nicely by alloying. That's particularly true in the
case of 10K gold rings. If you understand the old marking laws, and the
strategy that was used in compliance with the laws, you quickly come to
understand that a 10K gold class ring, made before '75, was most likely
really only 9K, which is illegal in the US. Nothing lower than 10K was
considered solid gold, but tolerance in manufacturing allowed for the
misleading marking, which made it legal. That is no longer true. They were
allowed 1/2% for alloy variation, and 1/2% for solder, which, while gold,
often is slightly lower in karat than the parent metal. Combined, they had
1% that could be substituted with base metals, a whopping 10% savings in
gold when you do the math. Considering the jewelry industry used to consume
gold by the ton for class rings, you can visualize the savings (or profit).
For the record, I processed enough class rings to know that what I say is
very true. The yield always bordered barely above 9%, and I was very
thorough in my processing----very little didn't report in the end product.
I realize that my stuff is light duty, low
Pretty much. I know for fact, due to having refined them in bulk, that many
of the contacts are a composite of tungsten and silver, predominantly
tungsten, which you quoted, above.. It's used for arc resistance as I
understand it, but then, as I said, I'm not a metallurgist.
While I never analyzed contacts for all elements (wasn't necessary*), I
believe that many of the smaller ones are alloyed with cadmium. Why, I
have no idea, but it wasn't uncommon to process a batch of small contacts
and come up with a surprisingly low amount of silver, and nothing else that
was identifiable with the processes I used. Again, when you consider the
value of each element, there are definite monetary advantages to alloying.
* Knowing what was present wasn't a factor. Silver is put into solution,
then extracted with copper. Anything else present of low or no value
remains in solution (zinc, copper, nickel, etc.). Gold can't be in solution
with silver (not in acid), and any traces of other precious metals (platinum
group) are precipitated along with the silver, so there's a complete
recovery of values. The only thing that otherwise goes with the silver is
the miniscule amount of base metal that is dragged down mechanically-----and
that is removed in the final process---along with other values-----by
Fine silver is suitable for low power DC circuits only, IIRC. The various
alloys are needed to handle mechanical battering, erosion resistance,
resistance to welding, vaporization resistance, etc. found in switchgear
and motor control equipment. The technology is well understood and has
been for many years since it was one of the first problems facing electrical
equipment makers in the early 20th century.
(thanks for correcting my goof on the silver via cyanide
process. And, Technic's solution for Ag recovery is probably
much less cost-effective than their Au solution.)
But, I am using a buffered cyanide (left that detail out). If
left too long in the solution, it will start to attack the
copper, but it is still pretty selective.
Dealing with refiners tends to be a losing
proposition------something I know
Thanks for that. I talked to a bunch of refiners some years ago,
and got a funny feeling about that whole business. Thanks for
confirming my feeling was right.
I used it when I was closing the doors on my refining business, to clean up
accumulated plated pins (wire wrap components). I processed something like
150 pounds of clean pins and strips. As you alluded, it works fairly well,
particularly when there's a nickel barrier. Given an opportunity, I'd
never use it if I had the option to strip with sulfuric acid, though. That
process is fast and clean, and certainly less hazardous than cyanide,
although hardly totally safe. You tend to run blind with the cyanide
The thing you need to watch is--- if it starts attacking copper, if it's
precipitating gold in the process. You'd never now, it doesn't look like
gold, it's just dark brown or black crud. It gets tossed, and you wonder
what happened to your gold.
If you don't know, our own government was (is?) involved in recovering gold
from plated items back in the '75, in New Mexico. They were using the
sulfuric process at the time. I was flown there by a client, who made
arrangements for me to inspect their stripping cell in order to duplicate it
for him. The trip was a grand success, and I built two stripping cells.
This was in the transition period, where I was still running my commercial
shop, but refining on the side for grins. I was shocked to hear that the
government had recovered what I recall was something like 35,000 ounces of
gold the previous year. Old microwave stuff was very heavily plated.
Some of it yields as high as 3% gold, which boggles the mind by today's
standards. I used to purchase wire wrap connectors and modify them for a
defense contract customer. The pins were plated with less than .0001"
gold, very unlike the stuff in question.
The screwing I got when I sold my platinum two years ago is hard to believe.
I recalled the material from one source when they tried to convince me that
it was down around 70%------the second refiner started off much better, but
still got to me over the long haul. They have you over a barrel with the
platinum group----there's a huge demand, but a very closed market. If
you're not on the inside, you can figure you're going to get screwed. I
wasn't, and I was. :-(
I have other war stories-equally as bad. Large refiners have no interest
in dealing with the common man, and make him sorry if he insists.
Well, I have several pounds of the TechniStrip-Au, and have
gotten to where I trust what it is doing. I have burned
EVERYTHING out, after much of the water evaporates. I did get
almost all the gold to precipitate out in the first
precipitation, once I got hold of the Zinc flour. (We discussed
this a year or so ago, and you directed me to some of these
tricks.) There's no doubt where the gold is, you just mash that
mud with a lab spatula and metallic gold appears! That is as
close to magic as I've seen in quite a while!
Much of the gold scrap I have is VERY old, some of it from vacuum
tube gear from the late 50's and the early transistor gear from
the 60's. The gold there is a LOT heavier than what was used
even by the 70's. I also have a modest pile of boards made using
gold resist, where the entire circuit traces are gold-plated,
they used the gold as the etching resist. There, it is not so
much the thickness of the gold, but that it covers the entire
Anyway, I'm building some processing gear like miniature drum
rollers to agitate the scrap in the solution, and will be doing
another batch soon. I need to reduce this big pile of scrap,
it is about 10 cu ft of stuff, some of it pretty dense like
just boxes of ckt board fingers.
Thanks again, Harold!
It would be pretty hard to lose values with the process you're using. The
only place you could possibly improve (if at all) would be to melt the
entire lot once collected and fuse it with litharge, then cupel it (the same
process as a fire assay, but much larger in volume). That's not for the
feint of heart, particularly without a cupel furnace. Besides, it's pretty
well frowned upon these days, putting all that lead in the atmosphere.
Welcome! Talking about it brings back some pretty fond memories.
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