Non-Chemical Sweating Silver

[Anonymous]

Over the past two years accumulated, eight 20 liter pails of contacts, primarily removed from electric ranges and hot water tanks.

I'm not prepared to sit for hours clipping the contacts off one by one and was wondering why not sweat them off.

My idea is to charge my ball mill which is just a large tumbler, add some heat, just enough to melt the silver and keep the mill rolling during cool down.

All Bakelite and plastic has been removed, my only concern would to keep safe by either working outside or under a fume hood to catch any potential fumes from the beryllium from spring copper and cadmium from the silver contacts.

Has anyone experience with sweating silver in this manor, or opinions on what I might do to improve on my proposed process.

My thoughts on this are that any copper that has a contact silver soldered onto it will oxidize during the initial heat, and that the silver and any silver buttons will find its way to the bottom of the tumbler once cooled down. I'm not worried about getting 100% recovery, 80 would be nice as I do not have any money tied up in this silver.

There are no silver contacts on tungsten wafers, these I sold on ebay and was very pleased with those auction returns.

Regards
G

 

[qst42know]

Will you be able to heat your tumbler to around 1600F and control it well enough to prevent the charge from fusing into a lump?

I haven't worked at the scale you are proposing but you may be better served attacking the base metals with HCL/peroxide or even AR leaving the silver behind for further processing.

Some small scale experiments might be worth exploring.

 

[Irons]

I think you meant Beryllium, not Barium.......

http://en.wikipedia.org/wiki/Beryllium

 

[lunker]

Gustavus,

I have removed contacts similar to this and you do not need to melt them. I used a 1/4' peice of steel pipe with a bicycle sproket welded on it and a small motor with a dimmer switch to control the speed . Use a propane tiger torch to Heat the pipe while it turns until the pipe turns red. about 20 min. You will see and hear the contacts start to fall off. Just keep the heat on for ten to fifteen minutes then cool it off while you allow the pipe to continue to turn. once it's cool empty it out and seperate the contacts. I have found alot of those type of contacts are monel and not silver at all. just something to keep in mind when you are processing them. best of luck!

 

[Barren Realms 007]

Gustavus,

I have removed contacts similar to this and you do not need to melt them. I used a 1/4' peice of steel pipe with a bicycle sproket welded on it and a small motor with a dimmer switch to control the speed . Use a propane tiger torch to Heat the pipe while it turns until the pipe turns red. about 20 min. You will see and hear the contacts start to fall off. Just keep the heat on for ten to fifteen minutes then cool it off while you allow the pipe to continue to turn. once it's cool empty it out and seperate the contacts. I have found alot of those type of contacts are monel and not silver at all. just something to keep in mind when you are processing them. best of luck!

That is an interesting set up. Maybe it could be put on an incline so you could do a continuous feed operation on a small scale.

 

[Anonymous]

Gustavus,

I have removed contacts similar to this and you do not need to melt them. I used a 1/4' peice of steel pipe with a bicycle sproket welded on it and a small motor with a dimmer switch to control the speed . Use a propane tiger torch to Heat the pipe while it turns until the pipe turns red. about 20 min. You will see and hear the contacts start to fall off. Just keep the heat on for ten to fifteen minutes then cool it off while you allow the pipe to continue to turn. once it's cool empty it out and seperate the contacts. I have found alot of those type of contacts are monel and not silver at all. just something to keep in mind when you are processing them. best of luck!

That is an interesting set up. Maybe it could be put on an incline so you could do a continuous feed operation on a small scale.

This might work for silver contacts of which are sweat soldered to the buss, the majority of the ones I deal with are a silver substrate on a copper rivet which are swagged onto the buss.

The contacts from electric ranges, washing machines and dryers are silver buttons which are themselves riveted to the buss forming a double sided contact.

Never yet run across any monel contacts.

 

[nickvc]

Gustavus i like the idea but fear its not going to work on all of the contacts.It might be better to sort the contacts into types roughly, hand strip a few, get them assayed and sell the bulk via e.bay when you know a rough value.This at least should get you close to realising their value,failing this a semi dissolution of the base metals and then time in your ball mill might prove another route to strip the contacts that the sweating wont sort.

 

[Barren Realms 007]

Never yet run across any monel contacts.

I'm not sure about the properties of the different contacts but I will find out with time. My shop is full of contacts, relays and a lot of other good kinds of stuff that as I find time I will tear them apart and find out what properties they contain and post results here if anything shows any promise. I have a combination of 3 companies that all worked in this area since the 50's or 60's. Until I combined 2 of them and the owner died in the 3rd one and I boght out lock stock and barrel. So I have a lot of old stuff.

 

[lunker]

The monel ones are usually magnetic.
I found alot of them were square with a slight bevel on each side and were in dryers and black plastic relays.