The Extraction of Gold from E-waste by Hydrometallurgy ...
Wong, et al used hydrometallurgy to extract valuable metals like gold, silver, selenium, tellurium from copper anode sludge. In this method, anode sludge without copper is used to extract silver, selenium, and gold. First, anode sludge without copper is leached into a roughly 4-9 molar nitric acid at 40-115 degrees Celsius.