daveerf,
On what parts have you seen Pd used on circuit board traces? On the link you gave, maybe there is someone interested in this scrap. Wonder what the minimum is for them to pick up? When they say unpopulated boards and trim, are they talking only about PWB manufacturing scrap?
Rag and Bone,
I am comparing this with two standard methods. The first is the old standard incineration, grind, screen, melt, etc. The second is to process everything mechanically - grind it and separate it into its various fractions using some hand sorting and lots of equipment - magnetic separators, eddy current separators, etc. There are a few patents on this second method.
Dissolving requires:
(1) - More labor and lots of equipment.
(2) - Much more fume control - hoods, scrubber, etc.
(3) - Much more waste to deal with - acid wastes mainly. For every ton of base metal dissolved, I would guess that you would generate at least 40 drums of acid waste.
(4) - Lower efficiency
(5) - Much higher chemical costs
(6) - Much slower process
Most anyone of you that has puttered around with these things know the above list is true.
Given a little time, I could surely think of more disadvantages. I was a very successful refiner, on a large professional level, for 40 years. The only other person here, that I know could make a similar claim is Harold. I may be wrong, but I think Harold would back up my contention that dissolving base metals on electronic materials is not the way to go in order to make money. Neither of us seem to get into many of the discussions involving these alternative dissolving methods for that very reason. Harold, if I'm wrong, please correct me.
I would love to be wrong about these things. If anyone could prove to me, with complete numbers, that one could profit from dissolving the base metals, I would gladly eat crow. BTW, in these numbers, labor must have a dollar value.