I had 50lbs of these handed to me and they said they were electrical components. Has anyone ran across these. I have been refining gold for a couple of years, and cement out the silver from the cooks. Just wandering what I'm dealing with.
Well I did take a bit and melted it when I got it. I didn't see any fumes. So I guess I was lucky. ThanksSilver cadmium contacts are common. The cadmium helps keep the contacts from burning as fast during the make and break cycle.
Be careful with them. Do not melt them. They will give off red cobweb like fumes that are very hazardous. If you refine them, be sure to treat the waste solution as highly toxic.
Dave
If these were just given to you, congratulationsI had 50lbs of these handed to me and they said they were electrical components. Has anyone ran across these. I have been refining gold for a couple of years, and cement out the silver from the cooks. Just wandering what I'm dealing with.
Welcome.New to the forum:
On the refining of AgCd alloys, as found in industrial grade electronic contacts, I had a thought.. rare, I know, but please hear me out, as it may be lunacy or brilliance, but I will rely on all of your expertise to guide me as to which.
Cd, Ag, Cu and many of the other components alloyed together all dissolve well in HNO3, leaving the more precious Au and platinum family metals in solid states. This is typical of the refining process, so, filter off the solids and save for future processing... now to remove the Cadmium from solution.
Looking at reactivity, Cu would not only cemet out the Silver, but also the Cadmium as a metal along with it... this is based on redox reactivity tables, so is there something I'm not seeing here? Many in the forums and vids state that dripping Ag with Cu, then Cu with Fe results in the Cd remaining in the slurry to be salted out... but that doesn't seem to work in principle. Or does it?
However, Ag would preferentially oxidize over Cd, causing it to drop out of solution as the silver is dissolved. Ag + Cd(HNO3)2 = AgNO3 + Cd (or there abouts)... so..!
If all of the Cadmium and associated alloys were dissolved in nitric to saturation, then fine silver were added, purified Cd would cemet out as a solid (insoluble) metal. After being filtered off, couldn't you just continue with any preferred silver refining method safely?
Again this is just a late-night though and I am open to any sanity checks anyone is willing to offer.
Thank you all!
Welcome.
I do not think you can do this selectively.
But if you add Salt or HCl to it, Silver will precipitate as Silver Chloride.
You will then be left with Cd which can be cemented on either Iron or Copper before waste treatment.
I'm not sure what version of the reactivity series you're looking at, but copper is several steps below cadmium. Copper is known to cement out only precious metals, and perhaps mercury if it is present.Looking at reactivity, Cu would not only cemet out the Silver, but also the Cadmium as a metal along with it... this is based on redox reactivity tables, so is there something I'm not seeing here? Many in the forums and vids state that dripping Ag with Cu, then Cu with Fe results in the Cd remaining in the slurry to be salted out... but that doesn't seem to work in principle. Or does it?
Thanks Dave!I'm not sure what version of the reactivity series you're looking at, but copper is several steps below cadmium. Copper is known to cement out only precious metals, and perhaps mercury if it is present.
Dave
Here are some links for you:Thanks Dave!
Perhaps I'm going about it wrong then in engaging from a purely theoretical perspective.
Playing with the chemical equations, it seemed to open the possibility of a clean way to cement the Cd using silver. It would require a volume of silver on hand... by the math, a stoichiometric amount, but math doesn't always work in practice. Haha!
Either way, metal refining and extraction is terribly interesting.
Thanks again all, for the feedback!
Yggdrasil,Here are some links for you:
Reactivity series: https://en.wikipedia.org/wiki/Reactivity_series
We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
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https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/
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Well, call me a newb, but I just figured out my issue with the whole line of reasoning above. When I balanced the equation I had done it in the reverse order. Basically, cadmium (if introduced) would actually cement out the silver, not the other way around.I'm not sure what version of the reactivity series you're looking at, but copper is several steps below cadmium. Copper is known to cement out only precious metals, and perhaps mercury if it is present.
Dave
I'm honestly not sure. I've been trying to work the math out on paper, and it looks like HCl would drop the Cd, but I'm not near as experienced as others on the forum.Your formula:
Add HCl to convert to chloride
Cd(NO3)2, AgNO3 + HCl -> CdCl2, AgCl
Correct me if I'm wrong at this point the HCL should only drop AgCl.
The cadmium should still be in solution of nitrate.
We try not to dissolve Silver in Ammonia as it can form explosive compounds.Ok... new idea that may allow for removal of Cd as CdCl2, in order to smooth extraction of other metals, and prepare for conversion into an insoluble for of cadmium salt.
Eager to hear your thoughts!
Disolve the potentially cadmium rich silver contacts in nitric.
Cd, Ag, Cu, + HNO3 -> Cd(NO3)2, AgNO3, Cu(NO3)2
Add HCl to convert to chloride
Cd(NO3)2, AgNO3 + HCl -> CdCl2, AgCl
Filter the Copper Nitrate off the chloride precipitate, rinse, and set it aside.
Add NH3 to both chlorides to disolve the silver chloride and leave the cadmium chloride as a solid percipitate.
CdCl2, AgCl + NH3 -> CdCl2, Ag(NH3)2
Filter the silver-bearing ammonium solution off, rinse.
Add Nitric acid to the silver solution to recreate silver nitrate and add sodium sulfide to the cadmium chloride to form an insoluble cadmium salt.
Ag(NH3)2 + HNO3 -> AgNO3
CdCl2 + NaS -> Cds
Edit: Ag(HN3)2 + HNO3 -> AgCl (not AgNO3
After that, you have a stable waste and can continue refining/extraction you silver, copper, etc.
Is this madness, too much effort, a pretty cool idea but not for a home refiner...?
Really eager to hear some feedback!
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