I figured I would mention this here since the discussion is about copper, and melting it into dore'
If you do have a large quantity of copper, check with SiPi to do your refining instead of sending it to a scrap yard. Here is the reason why.
Copper used in pipes and wire is of high purity, usually 99.9+ % copper specially for heavy duty electrical applications. However, there is that small percentage that isn't copper. Interesting thing about this is that if you have enough copper, you can start to retrieve the minute amounts of precious metals. It's that .01% that isn't copper, that starts to build up. Then when you send your copper to be refined at SiPi, you tell them you want what's call a "full accountability".
What happens when copper is run in an electrolytic cell, the copper is put in a basket that prevents the other metals from mixing with the copper as it dissolves into solution, makes it's way through the filter bag, and plate out on the cathode. What is left behind is called "anode slimes" and contains precious metals among others. If you don't ask for full accountability the refinery isn't going to talk about anode slims, and retains the values. The money is not in the copper they refine, but in the residual precious metals left as anode slimes.
So if you ship off 4-5 thousand lbs of copper, you might have 1-15 ounces, or possibly more, of gold and other PMs retained as anode slimes.
Scott
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