# Silver Contacts



## Profikiskery (Jul 13, 2016)

My first attempt to expand beyond just sterling scrap. Had a customer give me 12.29 very clean silver contacts about 3/4 inch in size. He claims they are about 90% silver and I trust him. He also gave me the contacts pictured. 

I have been trimming the small buttons off of what you see but with the tools I have it is labor intensive. The light sheers I have do well with sterling scrap, but not so much with trimming these. 

My plan is to just process this alone to see what it yields.


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## johnny309 (Jul 13, 2016)

STOP!!!!
First you have to mechanically remove any screw and spring(a lot of iron).
Then you have to close cut the contact point.....it is a lot a copper(even if is silver plated ) and brass to make you lose much more precious acid in the process.

P.S.: What you have right now is a max 20% Ag for all the weight.... and I see that you have some cadmium in your contacts(the milky ones in color ).


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## Aristo (Jul 13, 2016)

https://www.youtube.com/watch?v=6TeVWYCZql4


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## warranty repair (Aug 21, 2016)

I thought I'd hijack this thread rather than start another to ask a question that I'm sure people will be able to answer and I can't really find a definitive answer on despite using the excellent search facility.

Through my pulling apart of things, I have encountered two types of silver contact. 

1. The type that is clearly a solid block of (alloyed) silver. This type obviously contains a good proportion of silver and is worth saving.

2. The second type is usually mushroom shaped and the stem forms a rivet type fastening through a buss bar. The 'mushroom' is nearly always copper and it has a silver capped top fused to the copper. On initial inspection it looks like the copper has been just plated with silver but by filing a groove in to the material the silver is actually quite thick (I would assume flash plating wouldn't give the desired mechanical resilience). 

Would any wise person suggest that these are worth keeping for the silver recovery?


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## butcher (Aug 21, 2016)

I am not sure without seeing the electrical contacts you speak of, but most of the silver contacts that are riveted I have seen have also been fairly high silver content.
Silver is not the only metals used for contacts, some of the metals can produce dangerous fumes when melted so take caution.

Searching the forum will be helpful use different keywords and authors.
Here are some metals you can expect to find:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=20969&p=215987&hilit=silver+contacts#p215987


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## goldsilverpro (Aug 21, 2016)

Many or most of the big (at least 1/2") square, rectangular, or round points are made from coin silver - 90Ag and 10Cu - assuming they aren't the silver-tungsten type. They are brazed onto the copper buss with a silver braze that usually contains cadmium. When you sweat them off the buss, you also pick up some of the Cu from the buss. Overall, you end up with metal that averages about 83% silver, in my experience


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## warranty repair (Aug 21, 2016)

Thanks for the replies. Rest assured I have no intention of melting anything!







These are the contacts I'm talking about. Hopefully you can see that the silver part is just at the top of the 'mushroom'. At a guess I'd say they would yield about 5% but are they worth bothering with?


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## butcher (Aug 21, 2016)

Those do look like copper with a thin coating of silver or another white metal.
You can try one in nitric, or in used copper II chloride solution with heating, and see what you get in the experiment.
It may be worth testing, I have seen some copper points plated with a thick coating of palladium (tractor magnetos).

Contacts are used in many different applications, High or low current, High current would need to handle Arcing when points open or close. whether it opens or closes under load (like in switching a motor on) or switching with the machine off (like in DC motor reversal operations), in low current applications where Arcing is not as much of a problem they will use a different metal or alloy. 

Many factors come into play in the designs of contacts: AC current or DC current, low or high voltages, how often the contact is expected to operate in a reasonable lifetime.

Very low current and low voltage like in digital electronic signal switching, where getting the signal through the switch is important for reliability, and the contact will not clean itself through arcing or wiping, and any oxidation would be a big problem, for instance in digital low current high-speed switching, as in a computer or other digital electronics you can expect to find gold involved. older telephone equipment used a lot of gold or palladium.

Knowing the application can give clues to the construction of contact ,for instance In high current AC contacts where high arcing are subject to melt the contact or weld them together you can expect silver and tungsten, where the switch or contact is not operated too often it may just be a thick coating of silver alloy onto copper, or where it may be operated often (opened and closed)have a thick large chunk as the silver alloy contact, Battery operated forklifts can have many very large silver alloy contacts over an ounce each...


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## marlyn (Oct 16, 2016)

Hi guys,

I've got about 7kgs of contacts you see on the picture below and about 20kg more is coming. To remove silver parts piece by piece, it would take a lot of time, not talking about being exposed to cadmium fumes during the process. Most of the metal mass is coper, probably zinc and silver, so I was thinking about the following way of process:

- melting it outside using furnace to one piece (let's say 1kg big),
- collecting copper using electrolysis 
- remelt the residue from the bottom of the cell once again and use silver cell to gain 99% pure silver

What do you think about it. Any experience with this type of material?


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## Smack (Oct 16, 2016)

Melt that all together? NOT a good idea. Get the proper chemicals for the type of process you want to follow but first make sure you know the process well.


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## etack (Oct 16, 2016)

If you already plan to put the bar in a Cu cell I wonder if you could just use that as feedstock without melting. This should leave just the silver in the basket??

Eric


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## marlyn (Oct 17, 2016)

etack said:


> If you already plan to put the bar in a Cu cell I wonder if you could just use that as feedstock without melting. This should leave just the silver in the basket??



Does not sound like bad idea. I will try this first.


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## g_axelsson (Oct 17, 2016)

I think that the base metal is brass, not pure copper.
It would foul the electrolyte of a copper cell in no time.

Göran


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## Smack (Oct 17, 2016)

Pretty sure I'm seeing some ferrous material in that mix, not to mention quite a bit of tin. I just can't see that stuff being good in a cell.


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## etack (Oct 18, 2016)

They look pretty good to me. Looks like the screws or springs rusted but I don't see any Fe in the mix. However if there is it's not the end of the world it can be picked out too. 

I also don't see all that much brass either. It's been my experience that Sn coated buss bars are Cu not brass. 

Anyway just a thought. I have 150-200 pounds on buss bars that it seems that might be a good way to remove the Ag with little or no work. 

Eric


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## kurtak (Oct 18, 2016)

Because these points are silver tungsten it will do no good to try to melt them (with the copper bus bars) to make a silver containing "copper" anode to run in a copper cell --- the points will not melt (thereby making the desired copper/silver anode) due to the tungsten --- in other words - only the copper bus bars will melt & when you pour the molten copper off - the silver/tungsten points will be in the bottom of your crucible

Like wise - putting them in a copper cell "as is" (bus bars with points still attached) will only deal with the copper going from anode basket to the cathode - with the silver/tungsten points left in the anode basket as silver/tungsten points

bottom line - ether way all you end up with is separating the "points" from the copper - with the "points" still needing to be processed by boiling them in nitric as I already said - sooo - they need to be de-soldered from the bus bar - then run in the boiling nitric (I am taking about a "low" boil - just enough to put the acid in motion)

Due to having to break them out of the plastic housing - the low silver content (30 - 40% silver) the small size of the points - the de-soldering process & needing to boil them in nitric --- these points IMO are hardly worth processing unless you have a LOT of them

Edit to add; - I have something like 6 - 8 --- 55 gallon drums full of these breakers - at current silver prices I won't even consider trying to process them --- if silver ever goes back up around $40 ozt I "might" consider process them then - which is the only reason I hang on to them & keep throwing them in barrels 

Kurt


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## kurtak (Oct 18, 2016)

Opps - I read etack's last post & somehow confused this thread with a different thread  

:arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=24688&p=261130#p261125 

So disregard my last post here as its a different subject about different material  

melting points & buss bars - of alloy points (rather the silver/tungsten points) to make anodes for a copper cell is certainly one way to go - you would likely need to add more copper to the melt to bring copper content up for better anodes in the copper cell

Kurt


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## marlyn (Oct 24, 2016)

Just to add: 
- there is no Fe in the mix, I went through all with a magnet and it's all clean. Just little traces of rust. Do I have to wash it first with HCl, or is there a risk, that oxide coating on silver contact will appear, blocking access of acids? 

- you're saying to run the batch through *copper cell first*. It's because copper is above silver (more reactive) in reactivity series AND silver is NOT going to react with CuSO4 *OR* just because copper is more reactive?

- you're saying NOT to run batch through *silver cell first*, because copper is above silver (more reactive) in reactivity series -> therefore silver and copper will be plated *OR* because copper will also react with AgNO3 -> therefore silver and copper is plated?

I'm trying to understand the topic at all. 
...I hope, my questions are understandable.


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