Anyone know exactly what these are? Silver Cadmium Oxide? Contacts?
- Thread starter Jkessans
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Silver 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
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
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. Thanks
stella polaris
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Be aware that the points is probably from a lot of diffrent brands and types. If one is none cadmium it does not mean the rest of them is it. 50 punds? Thats is a very high cadmium chance.
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If these were just given to you, congratulations
Contacts from breakers and switches for high powers can be made of numerous, mainly high silver alloys.
Most common are AgCd and AgCdO points. These are metallic in properties, if you try to cut them with pliers, it goes as expected (relatively soft and malleable metal) and they show clear cut and metallic luster.
Good indication of cadmium is yellowish/reddish/brownish oxidation on them - as when they were de-soldered, heat transform surface Cd into CdO.
Then there are AgC contacts - sintered silver carbon powders. If you try to break these, they will start to crack/crumble, showing matt inside. If you then re-heat them with torch, metallic luster will re-appear. As matter of feel - these are significantly lighter (lower density), then AgCd types.
Big category are magnetic ones - another time, sintered powders of mainly Ag/Ni/C and W. Also, there are AgW types, non magnetic, but also crumbles when attempted to cut. Easily separated from the bulk by stronger magnet.
Then, there are solid tungsten contacts. Very heavy for the size (you can recognize them by feel in the "trained" hand), nitric won´t dissolve them - they only oxidize on the surface.
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If you intend to sell them, there is high chance refinery will give you significant penalty charge for cadmium content. Be aware of that.
Refining these is straightforward in terms of chemistry, but very cumbersome when you will deal with waste - if you will go wet route (dissolve in nitric and then whatever you do next). Cadmium is hard to scavenge from the spent liquors, as it does not cement on iron, and reacts with water if attempted to cement on aluminium. Hydrolytic tratment of waste also leave traces of Cd in the liquor. Only chance to scavenge those is drop them as sulfide or H2S (very nasty procedure on it´s own).
Cadmium is very toxic for aquatic life, and be sure they will notice it if you decide to deliberately pour it down the drain - when you kill all microbes in waste treatment facility, and everything downstream from it.
Only sane way how to process this quantity is to oxidatively smelt those - while carefully scrubbing evolved CdO vapors/fumes into bag scrubber. This is delicate operation and if you don´t have appropriate equipment, you can easily poison your whole neighborhood with cadmium forever.
Nice about this is all cadmium is contained and non-diluted and require no further treatment, only proper disposal as very hazardous waste to certified company (which would be pricey, but at least, you won´t have gallons of it
).Be safe and don´t melt them until you will have strong fumehood and reliably working, and efficient bag scrubber. Think more than twice before you process or dissolve them in quantity, as you can create big big headaches for yourself in the future. When you will be sitting above 5 gallon bucket with few kilos of Cd in it, wondering what to do next, after given the price tag from waste disposal company
Looks like to me I am going to sort all the pieces. I think there are 5 different types. I'll send them for testing, if they have Cd I just won't refine those. I do all my refining outside, but it sounds pretty risky. I've never tried or viewed --oxidatively smelt and scrubbing evolved CdO vapors/fumes into bag scrubber. Thank you for the info, might have save me from lung cancer.
stella polaris
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How is the AgCd to electro refine?
Solid Silver
Member
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..!
(Edit: the equation above is correct, but written in the reverse order, making the query moot.)
If all of the Cadmium and associated alloys were dissolved in nitric to saturation, then fine silver were added, purified Cd would cement 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!
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..!
(Edit: the equation above is correct, but written in the reverse order, making the query moot.)
If all of the Cadmium and associated alloys were dissolved in nitric to saturation, then fine silver were added, purified Cd would cement 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!
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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 have been running lots of contacts lately.
Been having issues but appears as Ygg states, Salt or HCL then deal with the waste seems to work well.
EDIT ADD: I dropped waste with zinc maybe a waste but have many pounds on hand.
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
Solid Silver
Member
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!
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!
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.
It is free here on the forum: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/
Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/
Forum rules is here.
https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/
Solid Silver
Member
Yggdrasil,
Thank you for the links and references! I've read through the community rules, and downloaded all the readings.
I've been following the community for a couple years now, so its nice to finally meet you all.
Solid Silver
Member
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.
Thanks for calling it out Dave. Like I said, it was a late-night thought. Apparently it was too late for chemistry. Haha!
Solid Silver
Member
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!
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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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.
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.
Solid Silver
Member
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.
Edit: Wait, does CdCl2 have a double reaction, due to the water in the dilute HNO3?
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We try not to dissolve Silver in Ammonia as it can form explosive compounds.
It is very important to re acidify as quick as possible after in that case.
