Removing silver from electrical contacts.

[Bigmarc]

Over the years I have been collecting electrical parts and have accumulated a fair pile. Has anyone separated the silver from the copper easily? Is there a quick easy method? Was thinking of getting one of those mini blowtorches but am unsure if it would get hot enough. Also I don't want to spend much money on this. Any ideas would be appreciated before I just throw the whole box on eBay. Cheers. 

[RacerCool]

I don't think it's that easy, just melting them down.  Look up sreetips on youtube.  He's a jeweler and he has tons of videos on how he melts and separates precious metals from things like electrical contacts, junk metal, etc. It involves various chemicals and multiple processes.

Then again he often tries to separate gold from various alloys so maybe it's the gold that's the difficult metal. But silver seems like it takes a lot to separate from other metals.

[Bigmarc]

I just want to separate the two. I think they are attached with silver solder or some sort of braising. So in theory i was going to try and get the bonding agent to melt not the metal. 

[LawrenceChard]

1 hour ago, Bigmarc said:

Over the years I have been collecting electrical parts and have accumulated a fair pile. Has anyone separated the silver from the copper easily? Is there a quick easy method? Was thinking of getting one of those mini blowtorches but am unsure if it would get hot enough. Also I don't want to spend much money on this. Any ideas would be appreciated before I just throw the whole box on eBay. Cheers. 

It sounds very labour intensive.

I would suggest melting the whole lot, get them assayed or refined in bulk, then either sell or arrange to get the silver back in some form or other.

You probably need quite a quantity to make this worthwhile.

[Uksilverstackers]

I’d probably do something along the lines Lawrence mentioned.

Cut off just the 100% copper only part and keep separate, then melt the whole remaining bonded silver/copper actual contact and then send that melted product off for assay, rather than melt the whole thing which would result in a higher copper content.

 

[Skyfiller]

Don’t know if I’m allowed to link to another forum but there are forums set up for this very thing. Google is your friend 😁

[Pete]

I would not be able to tell if an electrical contact was silver, tin or some other alloy.
Even if silver, it would be a microscopically thin layer so in terms of value - I doubt it would cover the cost of raw chemicals or energy to melt.
There are numerous Youtube videos of people risking their life, fire, explosion and serious life-changing burns using boiling nitric and sulphuric acids etc.
Ask yourself if it is really worth it vs selling it as scrap metal.

[Bigmarc]

1 hour ago, Pete said:

I would not be able to tell if an electrical contact was silver, tin or some other alloy.
Even if silver, it would be a microscopically thin layer so in terms of value - I doubt it would cover the cost of raw chemicals or energy to melt.
There are numerous Youtube videos of people risking their life, fire, explosion and serious life-changing burns using boiling nitric and sulphuric acids etc.
Ask yourself if it is really worth it vs selling it as scrap metal.

Depends on the current going through that particular contact. Yes 99% is copper but at the point where the two contacts touch it's obvious silver tab. If it's not silver then it has to have a higher performance than copper to prevent arcing and cope with the current. So far the best way I see is to heat up the back and tap it of. I may try a few or just eBay them at some point. I am a service engineer so I just rip them out at the time and bin the rest. You are all right, it's probably not worth my while but it's more of a fact finding mission rather than a money making exercise. Cheers for your input.

[Pete]

5 minutes ago, Bigmarc said:

Depends on the current going through that particular contact. Yes 99% is copper but at the point where the two contacts touch it's obvious silver tab. If it's not silver then it has to have a higher performance than copper to prevent arcing and cope with the current. So far the best way I see is to heat up the back and tap it of. I may try a few or just eBay them at some point. I am a service engineer so I just rip them out at the time and bin the rest. You are all right, it's probably not worth my while but it's more of a fact finding mission rather than a money making exercise. Cheers for your input.

You are correct that silver plating on copper would make sense but cheaper connectors may just be lead / tin / silver dip - I don't know.
I have some audio and video connectors that are gold plated but the value of the gold, if it could be extracted, is next to nothing.
I read somewhere that you could coat the roof of the Albert Hall in gold using only 2 sovereigns.

Back of the envelope calculation ( I am very rusty in maths these days so forgive any error ) I worked out that an ounce of silver essentially worth £17 these days would coat electrical conductors with a 20 micron plate thickness an area approximately 40 x 40 cm. If a connection measured say 5 x 5 mm that is approximately  6,400 connectors !!
You need to do the maths but is seems an awful lot of expense, not including labour to get an ounce of silver from a big bag of bits.
Good luck and keep us posted.

[danmc82]

Silver melts at 961 degrees Celsius. If you can keep the temperature below Coppers melting point of 1085 degrees Celsius you'll have molten Silver 😁

[Bimetallic]

3 hours ago, Pete said:

Back of the envelope calculation ( I am very rusty in maths these days so forgive any error ) I worked out that an ounce of silver essentially worth £17 these days would coat electrical conductors with a 20 micron plate thickness an area approximately 40 x 40 cm. If a connection measured say 5 x 5 mm that is approximately  6,400 connectors !!
You need to do the maths but is seems an awful lot of expense, not including labour to get an ounce of silver from a big bag of bits.
Good luck and keep us posted.

I thought your numbers were way off, but they weren't – you're pretty close.

Silver density: 10.49 grams/cm³

A troy ounce is exactly 31.1034768 grams due to the International Yard and Pound Agreement of 1959.

So one troy ounce is 31.1034768 / 10.49 = 2.965 cm³ volume.

A cm³ is a trillion cubic microns, so 2.965 trillion / 20 microns = 148.25 billion square microns of plating area.

We divide 148.25 billion by 100 million to get the microns back to cm, and it comes to 1,482.5 cm².

I thought it was going to cover a lot more area than that, but you were right there with your estimate of 1,600 cm² (your 40 × 40 cm square).

I've seen a lot of conflicting estimates of silver plating thickness for electrical contacts. Some sources give single-digit microns, e.g. 7 microns. Other sources, like these crazy Canadians, seem to imply that there are contacts that are more or less solid silver. See how they melted a bunch of contacts into a silver bar. I'm not sure what sort of products have the solid silver contacts they feature in their article.

Note that silver plated contacts are usually an alloy, not pure silver. There's silver cadmium alloy, which tends to be 75-90% silver, tungsten silver at 25-50% silver, silver nickel at maybe 90% silver, etc.

Arch Enterprises pays only $10-15 per pound of silver contacts (or they did in Oct 2010 when silver was about $23 an ounce, almost identical to today). I'm confused by what they're talking about. They're treating "silver contacts" as some sort of known, discrete object with predictable amounts of silver and whatever else. But at $10-15 a pound, they can't possibly mean stuff that's mostly silver. If that's the case, I'm not sure what the cutoff for a "contact" is, since there could be any arbitrary length of copper wire attached, or maybe they're talking about something detachable.

[Bigmarc]

I'm at work now and have taken a couple of pics of the actual parts. I will attempt to heat the copper up from behind to hopefully melt the bonding agent. 

 

 

 

 

[SidS]

I guess most ways of separating them would be to use chemicals, something to dissolve the copper, using the reactivity scale. As stated above though, compared to gold, silver is more tricky as it is more reactive and will get itself involved in the chemical reactions, like the copper does.

[greendragon]

they do look kinda chunky

i would be very temped to put one in a vise , and give it a few cracks with a very sharp chisel

a bit of random violence can work wonders you know