Extracting gold from copper
Jul 09, 2012· 2006. A. Dissolve all with aqua regia, then ppt out the copper with NaCl, then filter out the copper chloride and then ppt out the gold as pure with sodium metabisulfite mixed with water. Filter the gold fines and smelt. You could try dissolution in Nitric acid and that leaves the residue as gold. With excessive Cu, there is a lot of acid gas, brown and irritating so be careful.