Non-Chemical Removing silver from contacts

[rusty]

The contacts come from washing machine and dryer timers, some electric hot water tanks, electric ranges and circuit breakers, the larger silver contacts from motor start and mag switches are removed with the torch.

Once I have removed the larger contacts I toss the copper buss into the ball mill along with the smaller contacts to remove any silver solder that stayed behind.

These in the picture below have spent time in the ball mill, the fine silver comes out mixed with a bit of iron, copper and brass powder, I leach this with dilute sulfuric acid to remove the zinc from the brass and any iron.

You can see the copper pads which were once silver plated, some of the older contacts were solid buttons with the largest weighing 1.3 gr.

 

[Geo]

for contact points that are too small to sweat off, i just throw them in a little AP and it leaves the silver points clean as a whistle.

 

[DarkspARCS]

for contact points that are too small to sweat off, i just throw them in a little AP and it leaves the silver points clean as a whistle.

thanks for the addendum Geo!

Are you using a 3:1 AP mix for your solution, and when you mean "contact points too small..." are you referring to points such as those found included on television pcbs that are enclosed in black or blue plastic casings and are attached to a copper coil? I've saved up a jar of these small contact points and have been waiting to find a way to salvage the silver/ palladium attached to them. Some of these points are attached to what appears to be brass, as well as an aluminum or silver armerature... will AP work with brass as well? If the armeratures are indeed aluminum... what recourse is there with working with that? I suppose close cutting the contact point and filing off the remaining aluminum is probably the only way to get the pm from off of its aluminum host heh...

 

[Geo]

AP works as well on brass as it does copper. and yes, what you are referring to is a relay (i think).if its aluminum, well, it shouldnt be any problem as it will dissolve in less than a minute. hcl attacks aluminum very aggressively. heres some examples.

and heres the points up close.

when i say TOO small to sweat off, this is what i mean.

 

[DarkspARCS]

yep, relays was what I was reffering to. I decided to go the AP route with the three pounds of contacts I'd salvaged and they all came back looking just like you showed them as lol.. little round buttons and squares. some of the silver colored armeratures I thought were aluminum didn't go into solution... guess that means they were silver as well lol. Won't know for sure though until I clean them up durring refining.

So.. do I run these in a sulphuric cell now? what kind of metal should I use as the cementing agent (anode?) lol. guess it's back to doing some more research!

 

[Geo]

treat them as you would any contact point. either dissolve in nitric and cement with copper for high purity silver or melt into an anode bar for a silver cell for 99.99+ silver.

 

[Oz]

Treat them as you would any contact point. Either dissolve in nitric and cement with copper for high purity silver or melt into an anode bar for a silver cell for 99.99+ silver.

Never melt silver contacts due to the great potential of cadmium being present.

 

[Geo]

thank you OZ, i should have noted the safety issue with melting contact points. its been discussed before and i forget that everyone doesnt read every post.

of coarse due to possible Cadmium contamination, any melting of contact points should be done inside a fume hood or outside with a strong breeze blowing. always wear PPE's including a respirator and gloves.never eat or smoke or pick your nose while melting contact points.clean tools and PPE's after working and wash cloths separate from household laundry. bath or shower directly after melting is finished.

 

[Smack]

Just finishing up a batch of contacts, about 750g. Lost about half the weight after nitric, heading out to finish it up. I'll post some pic's.

 

[DarkspARCS]

Ugg... cadmium. Looks like I'll dissolve in nitric, and use a silver coated copper wire to cement with. would 13% nitric work in a high temp cell? and.. what do I use to rid the solution of any cadmium? Just neutralize and discard? or? lol?.?¿

oops... my question mark fell!

 

[Geo]

cadmium will stay in solution. from what i understand about cadmium is, it its toxic to inhale or ingest.so dont breath the smoke and dont drink your solutions.

 

[MysticColby]

dont drink your solutions.

I always love these warnings

 

[MMFJ]

dont drink your solutions.

I just prefer to drink TO my solutions (whether they work out or not!

 

[Smack]

749g. circuit breaker contacts
400g. of contacts left after nitric acid
224g. of once refined silver
This was a mixed lot of plated and non plated contacts.

 

[Smack]

I did get another 10g. of silver after further treatment with nitric acid.