# weird W Ag contact



## etack (Apr 8, 2013)

I received some silver contacts to refine and the are waffled on the back. They were 1.5"X1.25" in size.
I ran them like normal SS pot with nitric and water. I set it on a burner and heated it. When the nitric ran it corse I filtered the liquid it was a lime green color to cement. This is the strange part, the filter was full of a dusty rose powder and it was a lot of it. This was different from any other WAg contact I have ran. But this is the really strange part. When I cemented it with Cu it came down as a real dark powder like cemented gold. It also precipitated a white powder that when you add water to it it turns the water navy blue like a dark ink. Has anyone ran into this?
I know they have Ag and W in them. I also know it contains no Pd as I tested it with DMG and it returned (-). I guess I want to know What you think the blue is and why do you think it reacted like this. Orat the least has anyone seen this before?

Eric


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## kurt (Apr 11, 2013)

Eric - the blue/ink color is tungsten that went into solution - though most of the W goes un-affected by the nitric a small amount does go into solution due to its being alloyed with the silver & the high heat used to leach the Ag from the W 

Kurt


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## johnny309 (Apr 11, 2013)

My thoughts:
1) rose powder....cadmium is present
2) green solution...I say Pd is present...giving the fact that your cement silver is black

The fact that they are mixed is the key question
contacts are made from a list of alloys(Ag-Cd...Ag-Pd...Ag-O...Ag-Ni)....

P.S.: the "waffle" mark on the back of the contact points is because the were punched thru the hole on the moving arm of the relay....that is the "mark" that remain from fixing the contact.


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## kurt (Apr 11, 2013)

johnny309 said:


> P.S.: the "waffle" mark on the back of the contact points is because the were punched thru the hole on the moving arm of the relay....that is the "mark" that remain from fixing the contact.



Johnny - Eric is talking about points that are actually made of a tungsten/silver alloy - they run about 60 -70% W & 30 - 40% Ag - they come out of circuit breakers & other hand thrown type contactors - they have an actually waffle pattern on the back of them because tungsten can not be brazed or soldered like copper &/or silver &/or many of the other alloys of copper & silver - so the waffle pattern on the back of the point gives it a rough/irregular surface for the solder/braze to grip when they solder/braze the point to the buss bar (moving arm) - these are different then the points found in relays & magnetic disconnects

Tungtsten is normally not affected by nitric acid - so in order to recover the Ag from this type of point you have to literally boil them in nitric to "leach" the Ag out of the W 

For the most part - the W goes un-affected by the nitric - so much so that the points retain there original shape & look but become very brittle once the AG is "leached" out --- as I said in my first post - due to the conditions of being an alloy & the high heat of the nitric to leach them - "some" W does end up in your solution - & some of the W will drag down with the silver when you recover your Ag from the Ag nitrate solution - however that is not a problem if you run your silver through a silver cell - it will stay in the anode bag with your anode slime

I have processed pounds at a time of this type of points that I pull out of "large" industrial circuit breakers (I don't mess with house hold breakers - there not worth the time & effort)

The only reason I do the industrial breakers is they have large copper bus bars in them that are worth going after - the points are just a bonus

Kurt


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## kurt (Apr 11, 2013)

Opps - Eric - I got so caught up in answering the blue ink thing (tungsten) that I forgot the other stuff - keep in mind when dealing with points (of any kind) that you can end up with a whole hoast of things - especially in the solder/braze - cadmium (very common) but tin, molydbenum, & nickle are also common

Kurt


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## etack (Apr 11, 2013)

Here is a pic of it cementing. It was filtered till clear and it had a green tent but tested (-) with DMG.

I redissolved it after melting it and I'm left with some shiney non dissolving metal. Will test this tonight.


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## jonn (Apr 30, 2013)

Did you ever test that? What was it? I'd be curious to know what produces that silver shine in your last photo.


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