# Yellow Metal Chloride from Silver Contacts refining



## MysticColby (Jan 10, 2012)

Hey, so I'm a little stumped.
I purchased some clean silver contacts on feeBay for a fairly good price. Turns out a large portion aren't silver, but it's still a pretty good price. Anyways, that's not the question.
I put the whole lot in a large beaker and added 1:1 diluted nitric. Not enough to dissolve all of it; about 1/3.
After adding the nitric over time, then heating, then cooling, then adding water, the solution was clear pale green (I'm thinking high nickel content).
Filtered, added copper.
solution turned navy blue, then black. Once silver settled, the liquid was a strong deep blue. The silver was much darker than usual (graphite colored), probably why the solution looked black for a time.
I decanted the liquid into a beaker and added some sodium chloride (I like to do this to be sure I have all of the silver reclaimed). No silver chloride was evident, but a pale yellow (cyber yellow) cloud appeared. It suspended easily, and settled eventually.

What could this cloud be?
I checked all the likely metal chlorides I thought might be in here but none of them matched.
Nickel chloride was the most likely, but only nickel chloride anhydrous is yellow (hydrate is green), and it's highly soluble.
I added maybe 20 g sodium chloride to 2 L and this stuff doesn't go into solution very well.
it seems to not dissolve at all in cold water, but does dissolve minimally in boiling water, and can go through a filter this way.
I'll post pictures when I get home

After reaching this point, I set that aside and went for round 2 (added more 1:1 diluted nitric to the contacts).
Again, the diluted solution was clear pale green.
Same colors as before: blue, black, graphite-colored silver (a large amount of silver was recovered).
But when I added sodium chloride to the decanted solution, there was no yellow cloud (very small amount of silver chloride, though). Guess it all came out in the first batch.
I know the contacts weren't all silver because there are still a lot of large pieces that look unreacted. I'll try a 3rd round, then measure the weights, then give feedback accordingly ^_^

I'm guessing there is a high PGM content in the silver, due to graphite color. In the near future, I plan to experiment with electricity to isolate the silver.
As a side note, I've been wondering about something. Is it effective to cement PGM on refined silver before cementing silver on copper?


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## butcher (Jan 11, 2012)

PGM is highly likely, try cementing on copper (it will take time).


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## nickvc (Jan 11, 2012)

As Butcher stated it is likely it's PGM contamination, poor you! The best way to recover them would be cementation and then use of a silver cell to part them but if you don't have a cell then convert your silver to chloride using HCl and filter and wash well and then cement the PGM with copper to recover your values.


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## Harold_V (Jan 11, 2012)

MysticColby said:


> I'm guessing there is a high PGM content in the silver, due to graphite color. In the near future, I plan to experiment with electricity to isolate the silver.
> As a side note, I've been wondering about something. Is it effective to cement PGM on refined silver before cementing silver on copper?


My money says it's not PGM's---for what you described is common for large silver contacts. 

No, I don't know what it is, but I suspect it's tungsten. Notice that you can wash the cemented silver with HCl and get a deep inky blue solution. 

When you do happen to have PGM's in solution with silver (platinum or palladium, each of which will turn the solution color towards green), it will cement, along with the silver, albeit last. Use copper, and allow it to remain in the solution until the color shifts to blue. Test with stannous chloride to ensure you have recovered all of the values. Also, stir the cemented silver well, to liberate solution that was trapped early on by cemented silver. Allow the copper to remain until the solution tests negative for silver and PGM's, after stirring well. 

Harold


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## butcher (Jan 11, 2012)

MysticColby,
This is one case I hope Harold is wrong, (problem is he is almost always right). 
And I hope you find it to be of value in this solution.

Do you know if these were high current contacts, which are more likely to have tungsten, where they are usually real hard to get dissolved?

Contact points can have many other metals besides silver, some of them in the PGM family, they can also have gold, gold is more likely found in small contacts that may have to carry very low currents with high accuracy, like in electronic switches.

Some of the metals you can find in contacts, points, or switches: 
Au, Pt, Pd, Ag, Rh, Ir, Os, Cu, Fe, Co, A, Cd, Mo, Sn, Pb, Hg, W, Mg, Ni, and oxides of these metals, possibly even some I do not know of.

Springs can contain beryllium, bronze, kovar.
The arms are usually copper or even brass, or steels.

Sometimes the contact point can be a valuable metal flashed on top of base metals, or silver, or an amalgam mix of two metals or of several metals.

Silver is probably the most abundant metal you will find. 

Tungsten (W) is usually used in high current types, its high melting point 3380 degrees C. makes it great for circuit breakers carrying high currents.
These can be difficult to dissolve, (some have a waffle back).
Some people use nitric acid to dissolve.
I like to use a little HCL with a strong hydrogen peroxide (in higher content than the HCl)

The metals used or combination of metals are chosen based on the purpose of the contact or switch (relay, breaker, switch), the voltage, current, working environment, inductance and capacitance of circuit, Arcing, welding oxidation pitting, inrush current, contact bouncing, whether AC or DC operation and so on.


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## MysticColby (Jan 11, 2012)

There were definitely some tungsten ones (could see waffle pattern), but not very many. I processed them anyways because I remember reading on here that they usually contain silver and it can be recovered from the tungsten using nitric and heat.

I could only hope it's valuable! There's quite a bit of it... But I let it cement for a long time, I wouldn't expect anything of value would of already been removed (as evident by no silver chloride appearing).

I think I'll just rinse it plenty of times with boiling water, then continue processing as if it were silver chloride (rinse to beaker, add sodium hydroxide, stir, filter, mix with sodium carbonate and borax, melt, rinse with water).
I'll then dissolve that in nitric and cement any silver, as I doubt I'll be able to rinse away all of the yellow stuff.
I expect that adding sodium hydroxide will turn whatever metal it is into a hydroxide, which should decompose to it's metal at high temperature. Most of them seem to do that... If it doesn't, it won't dissolve in nitric, and be removed then ^_^


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## kurt (Jan 12, 2012)

In order to get “all” of the silver out of the tungsten/silver alloy points you will need to “boil” them in the nitric in order to effectively “leach” out the silver. Due to boiling you will get a greater rate of water evaporation so you should dilute the nitric a little more then 50/50 &/or add a little water from time to time while boiling. 

You can tell when you have leached all the silver out of the tungsten by fishing out one of the largest points & braking it in half. They become very brittle after the silver is leached out & they will be an even color of a darker gray all the way to the center. If the center has a lighter gray to it then there is still silver that hasn’t leached out yet.

They will run around 25 -30% silver & about 70 – 75% tungsten

Kurt


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## kurt (Jan 12, 2012)

I have some of this same type stuff sitting on the shelf from a batch of points I processed about 8 months ago. I asked the same question back then & know one seemed to have a clear answer on it then ether. So I kept it with the intent to come back to it & run some tests on it to see if I could figure out what it was. Guess its time to run those test.

Will keep you posted.

Kurt


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## MysticColby (Jan 12, 2012)

hehe, it's encouraging to know I'm not the only one stumped by this.

This is what I have thought so far:
It didn't react with copper, so it's above copper in reactivity series (Metal-NO3 + Cu didn't form Metal + Cu(NO3)2)
It did react with sodium, so it's below sodium in reactivity series (Metal-NO3 + NaCl did form Metal-Cl + NaNO3)
That leaves these possibilities:
Li - Lithium (chloride is white and soluble)
Ba - Barium (chloride is white and soluble)
Sr - Strontium (chloride is white and soluble)
Ca - Calcium (chloride is white and soluble)
Mg - Magnesium (chloride is white and soluble)
Al - Aluminum (chloride is white and soluble or yellow and soluble) "samples are often contaminated with iron trichloride, giving it a yellow colour"
Mn - Manganese (chloride is pink and soluble)
Zn - Zinc (chloride is white and soluble)
Cr - Chromium (chloride is purple or green and soluble)
Fe - Iron (chloride is tan or pale green and soluble or yellow solid and soluble or brown solution and soluble)
Cd - Cadmium (chloride is white and soluble)
Co - Cobalt (chloride is red and soluble)
Ni - Nickel (chloride is yellow-green and soluble)
Sn - Tin (chloride is white and soluble)
Pb - Lead (chloride is white and slightly soluble)
Sb - Antimony (chloride is white and soluble)
Bi - Bismuth (chloride is white to yellow and decomposes in water)

So, nothing on this list is very valuable. That's why I'm not going to fret over it. But, it's a puzzle!
could see if it reacts with something like Iron hydroixde. That would narrow down the list. (But it's not very soluble - would work better if something that was was used)
I didn't even take inorganic chemistry (though I now feel confident I'd do well in it, after working with silver ), so I don't know without looking up everything what might work.

Going off colors alone, we have some likely candidates:
Al - Aluminum (chloride is white and soluble or yellow and soluble) "samples are often contaminated with iron trichloride, giving it a yellow colour"
Fe - Iron (chloride is tan or pale green and soluble or yellow solid and soluble or brown solution and soluble)
Ni - Nickel (chloride is yellow-green and soluble)
trouble is, they are all soluble in water.... (at least 450 g/L)
I believe I've rinsed this enough that all acid and other nitrates are gone
I'm not so sure it's nickel - the second batch solution was pale green, indicating nickel, but that didn't form any yellow precipitate when I added sodium chloride. And if nickel was in batch 2, something more reactive would of had to of come out sooner (but there was silver in batch 1, which didn't react with the nickel that came out in batch 2... so not conclusive)


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## MysticColby (Jan 16, 2012)

latest update:
it doe react with sodium hydroxide. the hydroxide form seems to dissolve better, and settles faster. Similar color, but more green.
current plan is to dry, incinerate, dissolve in nitric, cement onto copper, neutralize with lime, discard.


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## metatp (Jan 18, 2012)

I found similar stuff when dissolving the contacts in the following picture. They were a pain to process and I got very little silver. I actually redissolve all the cemented silver again to clean up a lot of drag drown material. Never found and value in the yellow of mauve stuff.

Tom


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## MysticColby (Feb 14, 2012)

latest info:
I melted this with lots of borax and sodium carbonate.
I then poured the whole thing into a bucket of water to make corn flakes.
There was quite a bit of silver (or silver-looking metal)
there was also a medium-strength sulfur smell (not while melting or pouring, but while picking through the flux in the bucket to get out the silver pieces)
there's quite a bit of flux stuck to the silver, so I'll remelt it with my next incineration then dissolve in nitric.

After this, I've decided not to produce silver chloride again


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