Hi Ross, At a mine in Nevada after the leach tank the solution was pumped through carbon ion exchange columns. After this stage they wanted to install an expensive smelting device. Our boss took the torch and an old oxygen cylinder. For about $50 he made a contraption that drew the ridicule of the geologist until they saw it in action. He had a bellows type device hooked to an air compressor and a hose ran into a bucket of water. The carbon was put into the cylinder. Next a stainless steel screen was put in and then, one or two charcoal lumps. Light the charcoal with fluid or a torch and turn the cylinder upside down. Eventually, the charcoal would ignite the carbon turning the cylinder red from the heat. When it cooled all that was left was about a 1/4 pan of blacken gold which was sent in the lab to be cleaned. So, unless you have some really high BTU coal consider charcoal which you can obtain at any supermarket. rhodium