The following I found for you on:
http://www.finishing.com/191/49.shtml
It was submitted by Richard Alcor, Cushing, OK, USA
There are a number of methods that may be used. Reverse electroplating is generally fairly simple and can be done using an automotive battery charger, a stainless steel plate, a carbon rod (or another stainless steel sheet), a 5 gallon detergent bucket and some commonly available (and inexpensive chemicals). This method works well for certain types of scrap; clipped leads and ends for instance and heavy plated scrap. Whole PCB scrap COULD also be done this way, but you would need to first crush and burn to reduce the volume and get rid of waste materials. You can also use AR (Aqua Regia method), Cyanide Leach (or alternative using a product called Cyanide Leach Substitute or CLS), mercury, etc.
I generally use AR for everything. Processors, memory and clipped leads all provide excellent returns. I also do the rest of the PCB, after crushing and burning. Hard drives, in my experience, take so long to dismantle that they are worth more to me as dirty aluminum scrap than anything. If you spend the time to come up with a better method for retrieving the scrap from the read/write head and platters inside the drive, then they too may be profitable (a lot of people swear by them).
In my experience, whole PCB board of mixed type from mixed sources will provide around 1-3USD/lb profit after expenses using AR.
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