I deplated my first 4 kilo's of brass contact pins in 96% Sulphuric with electricity.
Downside: slow process, need to monitor it and replace a copper contact rod around in the basket. concentrated H2SO4=danger, need to dilute the acid with the gold after settling and siphoning off. Can leave traces of gold on the base metal.
Upside: amost no basemetals dissolved, less waste.
Second method: dissolve in AP. Lots of waste or AP to reuse.
Third method: (if there is a lot of copper underneath) melt it all together and run it through a copper sulfate cell.
My yield with the sulfuric stripping cell was .3% of the weight. So 3 grams per kilo. Those were small and a lot of surface area per weight. Chains could be thick, bringing the surface / weight ratio further down.
It can be .5 gram per kilo or maybe up to 5 grams per kilo.
After the sufuric stripping cell, i had a lot of little gold plate spots and underneath the clamped parts where the wire insulation is inserted. So i went on to the copper sulfate cell to get the last bits out and get acquianted with the process.
Have not refined the collected anode slimes yet.
Cyanide sounds scary, but with the right safety measures could be the easiest way, never tried it.
And then there is the iodine leach, which still is being fine tuned.
Like the stores these days...too many options to choose from. I hope this helps you and does not confuse you too much. It all depends on the type of base metal and how much time you are willing to spend on it.
Any idea whats the base metal?
Martijn.