Silver electrical contacts

[razzel8]

Hello all. I have read this forum and am amazed at the info I have found here. I have an electrical degree and work in and around relays, starters, and breakers. I have seen on this web site and through other internet searches that many of these contacts have either a silver alloy or solid silver tip. From what I can gather it is a lot of trouble and maybe dangerous to a persons health to separate these but it seems as thou some of you have had some success. The question I have is what's a good way to know if they are even silver to begin with? Surely not every one is tested? Some relays and starters state right on them the silver percent but the majority do not say anything, yet the tips look the same. These are currently going in the trash when I have determined them to be faulty as my company has no interest in any scrap value. I have also downloaded and read Hokes books and as much info as i can find on silver and gold refining but have never tried anything. At this stage I am just fascinated at what many on here have accomplished and just in an accumulating mode.
Thanks.
Raz

 

[butcher]

razzel8, electrical and electronic use of these metals is a big part of why they are mined.
Silver gold and even platinum group metals are used in the electrical and electronic products.

you do not have to always test for these metals when you know where they are and when they use them, sometimes we may test for them other times we know where they are used, sometimes you can even see the metal, many time's you cannot see the metals your trying to recover.

these metals will give certain properties that are very useful in electronic and electrical equipment, conductivity, low resistance, corrosion resistance, low arching, low welding, changes softness or harness properties, able to make good conductor and cheap to put on plastic films, and for many other reasons.

very seldom do manufactures state on a piece of equipment what or how much of a metal they contain, seldom will you find this on data or specification sheets (but sometimes you can), what or how much metal may or may not be important to the end user or builder.

Read more on the forum we have talked about this for years, there is a lot to learn.
Just keep studying you will soon know where to look and know how to recover and refine.

Welcome to the forum Raz.

Edit: to add our landfill will be our mines someday.

 

[element47]

Your basic proposition is to read and study and research and inquire until you believe you have the information to act (or not) Until then, accumulate, as you appear to be doing. Some folks should probably not mix chemicals...maybe they are clumsy, maybe they think they know better than to follow very strict directions, who knows. Some folks who have kids and pets and small apartments also should probably not mix chemicals. To do this stuff safely, you have to have (meaning, "buy") safety equipment and that's not optional. If you only use it once, it's probably not such a good idea to become engaged in refining. I believe that in the end, there are very, very few people who should be doing this on a regular basis. And I find nothing wrong with that conclusion. It's not like learning a musical instrument. There, you can make the decision, go out & buy an instrument, and if you decide it isn't for you, all you're out is time and money. With refining, you could permanently injure yourself if you're not careful. You're in the right place to learn, that much can be said.

In my own case, I have gathered many hundreds of pounds of sterling flatware, and I have perused this forum for roughly a year trying to figure out whether I should try to refine it myself. I really enjoy reading about the different processes and I've read Hoke a time a or two. I am not going to tell you that I am any kind of expert, but I do think I know what is involved. And for me, I have determined that it is not a good idea. The negatives are a combination of available setup area, my own patience, difficulty of obtaining chemicals, time, disposal, and various other things. But that's just for me. In the case of others, those others may come to a different conclusion. Kadriver has been around here roughly the same amount of time that I have, but he refines and successfully produces absolutely beautiful silver (and some gold) bars. I can tell you that I would have been a lot more interested in this when I was a tad younger and the miscellaneous negatives would not have deterred me in the direction (the direction of not doing this stuff myself) I have chosen.

The values patiently sit in the materials you gather. Over time, you'll probably research and/or figure out a way to test what you have, but you'll also find that you don't have to test each and every bit of metal you have. Maybe you will have 5 different manufacturers' relay contacts and the Siemens ones will be really good and the GE ones will be poor. I think if you just stay interested, you'll eventually run into someone in your area who will do the refining (and maybe the testing) for a piece of the action and you'll make a deal. On the other hand, if all you can gather is a cupful of relay contacts, there isn't enough to bother with (except as a matter of curiosity) and so you probably shouldn't buy the chemware and the safety gear.

 

[razzel8]

That has been a big disappointment to me, having the name, model and even series number of the parts in hand and still not being able to find the data I'm looking for from a manufactures web site. From a manufacturers point of view I would expect they would want to use the least possible pm's and still be able to maintain their quality standard. So I do wonder how much could truly be present. However, most of the equipment I am around is high amp applications so the possibilities are there for high silver content.

Refining is still way out of my reach. Even thou I have read quite a bit, i still feel I am missing something, so no worry that I will hurt myself yet.

Raz

 

[Harold_V]

However, most of the equipment I am around is high amp applications so the possibilities are there for high silver content.

I agree, and silver is one of the easiest of metals to test. Schwerter's solution and a drop of nitric acid can reveal everything you need to know about a contact in almost all cases.
If you can find a source for a fluid ounce of nitric, you can test hundreds of items with little effort.

Once you get familiar with what silver contacts look like, you'll most likely be able to identify them visually. Considering you are discussing high amperage, there's a good possibility that the contacts you'll gather will be high in tungsten. They can still be processed for silver, although they contain less than 50% silver.

If you feel you aren't ready for refining, simply store what you save, but save only values. You'll do that by testing.

Harold

 

[Geo]

silver is used in these types of applications because of its ability to withstand the high temps that are created from the plasma arc when the contacts come together or are pulled apart as well as its ability to resist corrosion after being heated. if you had to assume that the majority of contacts are a silver alloy you would not be mistaken.the one other metal (that i know of) that is widely used in contact breakers is tungsten. there are a couple of different ways of determining whether a contact is silver or tungsten without acid testing. a visual comparison usually will be all thats needed for example : is the contact new or used. if its been used a silver contact will have a white appearance and a tungsten contact will be dark almost black. if the contact has been sweated off the base is the bottom of the contact pad smooth or does it have a waffle pattern, smooth will be silver, waffle will be tungsten. tungsten is primarily used in breaker switches.

 

[Harold_V]

It should also be noted that silver is the best conductor of electricity, so high amperage applications almost demand its use.

Harold

 

[slickdogg]

I thought gold was the best conductor of electricity? Was I lied too?

 

[jimdoc]

http://wiki.answers.com/Q/What_is_the_best_conductor_of_heat_and_electricity

 

[Westerngs]

A word of caution to those working with silver contacts:

Many silver contacts are 90% silver 10% cadmium.

Cadmium is a toxic metal and should only be melted if you have very good ventilation.

you can tell if your contacts have cadmium if when you dissolve some in nitric acid the solution seems oily.

A less safe way is to melt a small amount without a flux cover. The cadmium will oxidize and the melt will evolve stringy brown fumes.

Always wear a respirator when melting material you suspect has cadmium. A good half face respirator with n100 filters is cheap, your health is not.

As a rule, I never melt cadmium bearing material, I just return it to its original owner and let them deal with it.

 

[razzel8]

Geo, if what you are saying is true than i must be working with a majority of tungten tips, because after use they all have a blackened, pitted surface. These pull high amps and when the coil drops out are reluctant to separate because of the current. I have ordered an acid test kit to take the mystery out of it and appease my curiosity.

Westerngs, is there any danger in this cadmium entering the air in the room where these contacts are arching as they are dropping in and out? I am frequently in this room where a large number of these relays are. As i have said these tips, when removed have been pitted (almost melted i guess you could say). So it seems I may already be breathing cadmium fumes as I'm sure it is probably alloyed with tungten also.

Thanks,
Raz

 

[Harold_V]

To my knowledge, the tungsten bearing contacts do not contain cadmium. They also contain less than 50% silver, so expect a limited (but worthwhile) recovery. A prolonged boil in dilute nitric (keep the vessel covered with a watch glass) will penetrate the tungsten and remove all the silver---but it's a slow process.

Harold

 

[Westerngs]

If you have tungsten based contacts there is nothing to worry about.

With silver/cadmium contacts, the only time you need to worry about cadmium fumes is if the contacts have gotten hot enough to melt. IF they melted, and did so in atmosphere (air), they will emit cadmium oxide fumes, which then are likely still in the room. I doubt your contacts have melted, it sounds more like they are just corroded from exposure.

 

[old thompson]

Geo, if what you are saying is true than i must be working with a majority of tungten tips, because after use they all have a blackened, pitted surface. These pull high amps and when the coil drops out are reluctant to separate because of the current. I have ordered an acid test kit to take the mystery out of it and appease my curiosity.

Silver alloy oxidizes when you put a high amperage arch through it and silver oxide is black, think tarnish. It is likely that blackened, pitted contacts would have higher silver content than ones that have seen heavy use but show little wear.

Try to scratch one of your contacts with a knife, the tungsten ones will hardly scratch at all and the blackened ones will scratch to reveal the shiny silver alloy beneath the tarnish.

 

[Geo]

Geo, if what you are saying is true than i must be working with a majority of tungten tips, because after use they all have a blackened, pitted surface. These pull high amps and when the coil drops out are reluctant to separate because of the current. I have ordered an acid test kit to take the mystery out of it and appease my curiosity.

Silver alloy oxidizes when you put a high amperage arch through it and silver oxide is black, think tarnish. It is likely that blackened, pitted contacts would have higher silver content than ones that have seen heavy use but show little wear.

Try to scratch one of your contacts with a knife, the tungsten ones will hardly scratch at all and the blackened ones will scratch to reveal the shiny silver alloy beneath the tarnish.

i agree. silver will tarnish black.silver contacts are much softer than tungsten. i say things without giving enough information sometimes. the tarnish on silver can usually be rubbed off with your finger where the black tungsten would seem to be black metal and will not rub off. the black tarnish on silver is more blotchy in appearance where a tungsten contact will have a more uniform color over the entire contact.

 

[Smack]

Silver contacts will bend, silver/tungsten will break. Silver plated copper and brass will also bend. Just saying it's easy to tell weather you have silver/tungsten contacts.

 

[Goldfinger4]

We could collect some ideas how to process bigger amounts. Heating or cutting every single contact to get rid of most of the cupper can't be the solution.
What about shreddering the contacts and seperating the silver by its density (like gold panning).
Unfortunately I didn't find small metal shredders.

 

[Harold_V]

We could collect some ideas how to process bigger amounts. Heating or cutting every single contact to get rid of most of the cupper can't be the solution.

It can't be? Don't know why not. It works, and very well, and is quite fast, in truth. If you're trying to remove silver contacts with anything less than a large torch, however, you're kidding yourself.

What about shreddering the contacts and seperating the silver by its density (like gold panning).
Unfortunately I didn't find small metal shredders.

Let me see if I understand this. You hope to find a shredder that will reduce these materials to crumbles, then separate them by panning?
While you're spending your time looking for an adequate shredder, I'll simply remove the 30 pounds or so of contacts, recover the silver and be doing something else while you're still fannying about with that idea.

If you use some wisdom, you can preheat contacts while you're removing each one. I did that, so it took but seconds per buss. Place them in a stack, then play your torch on the one being removed while it's over the stack. The heat lost is absorbed by the stack, so they're already preheated, often near the melting point of the solder. You can go through a large number of these things in an hour, likely one hell of a lot more of them than you can hope to accumulate.

Unless you see yourself processing nothing but large contacts, I'm not convinced your idea is sound. Even then, it may not work well because you won't achieve the type of separation you hope for, and the recovered copper won't be useful for cementation, is it would be if you removed contacts by torch.

Harold

 

[MysticColby]

I had the thought to simply use the copper with the silver contact to cement silver. Once the bar is totally dissolved, the silver button would release, and already be part of other silver.
I expect it wouldn't be as pure as otherwise-cemented silver. If you then add a small amount of nitric, some of the remaining solder contaminants would dissolve first (I don't know what it's made of, but it should all be things more reactive than silver)
This would of course require a huge amount of other silver also being processed, which is unlikely if you are dealing with silver contacts.
But I must admit - it doesn't take much fuel to take these things off.

 

[butcher]

If you use a torch of proper size de-soldering contacts is quick, it almost takes half the time just picking one up with the pliers as it does to melt off the contact.

I do sometimes use the large piece of copper bar to cement other solutions, and do recover some of the solder or silver plate, but it would take forever to de-solder a batch of contacts this way, as one bar of copper lasts a long time cementing values from solutions.

Maybe you just need a better torch setup, or a different tip on your torch?