This how I process my cons..
Cleaning your cons
I pan and remove all the gold you can see and bring everything else home. I screen every thing with 25, 50, 100 200 mesh keeping them in separate buckets. I save the plus 25 mesh for later if my rods show that there is gold in it. I then soak the cons with vinegar ( it's cheap at Sam's Club.) for three days stirring it when ever I think of it.
I run it thought the blue bowl starting with the 25 mesh lowering the water level for each size collecting the gold as I go. I now have all the cons back in one bucket. I now take my hot plate outside ( the heat range dial goes from 1-7 and I have it at 3 1/2 ) and using a pyrex bowl dry it and dump each batch into a tub of cold water ( cracks the cons )
The next step I used a cement mixer when I was getting large amounts of cons from my big Dredges but now I use a rock tumbler. I put each batch in the tumbler with 4 half inch stainless steel ball bearings and turn it for two days ( more or less ) then add Mercury for another day. When I have all the cons back in a bucket I go back to the Blue Bowl.
I run it at a high water level and then at the lowest water level collecting the gold-mercury in snuffer bottles saving all the black sand. I pour all the gold-mercury into a newer pan ( the least amount of scratches ) working it with a small amount of water to bring all the mercury together taking the black sand out as I go. Using PLASTIC GLOVES I put a piece of fine silk over a pan and pour the gold-mercury into it. Grabbing the silk by the sides you can squish the excess mercury out of the silk saving the mercury for next year. You now dump the stuff in the silk into your pyrex bowl.
I then load my PU. I take a potable generator, hot plate, jugs of water, Soda, gold-mercury, saftey mask, Nitric acid and the remaining black sand and go to a friends 20 acres of isolated land. I set everything up, start the generator, put on my mask, pour the nitric acid into the bowl and walk away for a 1/2 hour. When I return I fill the bowl with water and soda and let it cool. I pour the water into a safe container and collect my gold. I then dry all the black sand to burn off any mercury that may be on it.
This is a long process but when it's raining and cold I set in the garage with a heater and drink a few beers while I run the blue bowl. My rods show me that there is still some gold in the black sand so I will crush it and start over.