silver coated copper sheet

[sena]

Hi every one, could we know the weight of silver coating over the copper sheet , a company used to make electrical contacts sells their scrap silver coated sheets , they say it is flash coating and weight of the scrap to be 3500kgs(silver coated copper sheet), the coating thickness is (0.30 micron flash coated),is that we can derive the approximate weight of the silver :?:

Thanks

regards
Sena

 

[goldsilverpro]

Hi every one, could we know the weight of silver coating over the copper sheet , a company used to make electrical contacts sells their scrap silver coated sheets , they say it is flash coating and weight of the scrap to be 3500kgs(silver coated copper sheet), the coating thickness is (0.30 micron flash coated),is that we can derive the approximate weight of the silver :?:

Hi, Sena,

That figures to be about 32 cents worth of silver per square foot of plated area. Not profitable at all in my estimation, considering its low value and what you would have to go through to recover it. To estimate the weight of silver per 3500kg of scrap, I would need to know the copper sheet thickness and whether it's coated on 1 side or 2 sides (probably 2 sides). As a guide, if the copper is 1/8" (3.175mm) thick and coated 2 sides, the silver value would be about 11 cents per pound of copper or about $850 (25 tr.oz.) worth on the entire 3500kg (3.5 metric tons) - about 0.02%. If the copper were twice as thick, there would only be half as much silver. Good luck stripping the silver. Even if you can strip the silver, good luck making a profit from it. Too low grade.

At that thickness, the silver is most probably applied by immersion (cementation) plating using no current. That is a very cheap way to do it - they just clean the copper and then dip it in the solution for 1-4 minutes, usually. The main difference between immersion plating and the cementation you're familiar with, is that the immersion plating bath is formulated so the cemented silver will tightly bond to the super clean copper and won't fall off. As the copper becomes coated with immersion silver, the plating will slow down and eventually stop. It's thickness is self-limiting. The 0.3 micron (12 microinch) thickness sounds about right as approaching the upper limit for good immersion silver plating. The silver plating on silver coated copper bussing, including those shorter pieces on which large contact points have been mounted, is usually applied by an immersion process. That's why I tell people that it's so thin they will lose money trying to recover it.

I think all the math is correct.

Chris

 

[sena]

here is some of its picture , the seller said its .8mm.

 

[goldsilverpro]

That's totally different stuff than what I was thinking of - I was thinking buss bar for some reason. If it's plated on 2 sides, it should be about 4 times (3.175/.8 ) higher than the numbers I gave you - about $0.44/pound = 28 tr.oz./mt. Being for electronics, I would guess the silver is electroplated and that there is nickel plate under the silver. With the copper being .8mm thick, I recalculated it in a different way and came up with about .09% silver, very close to 4 times more.

Were it me, I would still turn it down unless I could profit by just buying and selling it, as is. I certainly wouldn't try to process it.

 

[EDI Refining]

I'm interested in this material.

Is it in your hands or do you still have to purchase them?

Does you customer know the Ag/Cu content?

Is a sample available?

let me know via PM , thanks

 

[sena]

Best idea to process the Ag coated scrap quantity is 3.5 ton?
Thanks
Sena

 

[samuel-a]

sena

Have you bought it yet?
Were it me, i'd pay for No. 2 copper. no more.

There's no profitable way which i can think of to seperate those metals from each other, other then large copper electrolysis bath.
You should turn profit not just on Ag, but also Cu and Ni. In my humble opinion, if you can't do that, pass the deal.

 

[sena]

i have got 10 kg as sample let me work it out , with sulphuric and nitric 3:1 ratio.

 

[goldsilverpro]

i have got 10 kg as sample let me work it out , with sulphuric and nitric 3:1 ratio.

Have you tried 3:1? I would think that it might eat some copper. The standard formula, which has been around 100 years, is a sulfuric/nitric ratio of 19:1, by volume. I would start there and then add a little nitric when the stripping slows down. The idea, of course, is to cram as much silver into the solution that it will dissolve.

 

[Geo]

i tried that process and it worked ok, but i think i had too much water in my solution because it dissolved quite a bit of copper. also i may have had it too hot.

 

[goldsilverpro]

i tried that process and it worked ok, but i think i had too much water in my solution because it dissolved quite a bit of copper. also i may have had it too hot.

I usually didn't heat it, unless the silver was unusually thick. Even then, I never went to the recommended 190F. For average silver thickness, it worked fairly well at room temperature. Agitation or just moving the material back and forth in the solution can speed up the stripping considerably.

This 95/5 solution was designed many years ago by the plating industry for the sole purpose of stripping defective silver plating off of copper parts so that the parts could be re-plated. Their interest was in the much more valuable parts and not the silver they were removing. In the old days, much of this silver solution was simply put down the drain. The solution was heated to speed things up. Probably, 190F was their limit because higher would have been to dangerous. Or, maybe, it starts eating the copper above 190F. Actually, it works at any temperature between about 70F-190F. The higher the temp, the faster it strips.

For your interest, here's a recent post on finishing.com.

http://www.finishing.com/585/76.shtml