Gary, If you are ever a little shy of a full crucible of pure copper just before a big pour, you can always use a little high school chemistry to make up four or five pounds of pure Cu to melt. It’s called a ‘single replacement reaction’ and basically involves the immersion of iron (Steel) bits, filings, and cut offs with a solution of Copper Sulfate which you can get in paper bags like fertilizer. A couple of plastic buckets, 10 of 15 pounds of Free iron filings and bits from your pals in Broomfield, some solution and one little, nylon fish tank skimmer net to gather the pure copper precipitate and you’re all set! Just takes about 5 or 6 days, that’s all.
Fe + CuSO4 to FeSO4 + Cu
The iron dissolves, leaving a grayish sludge, (iron sulfate) and pure copper.
FYI,
Mike and Tracy