In phones, most of the gold is in the SIM card, the main board and the smaller components on the back of the LCD screen. Use a magnet to separate all gold-plated steel parts, as you need a different process to extract it. "Older electronics have more gold in them," says Murchison. "The best thing I extracted gold from was industrial video equipment -- a couple of ounces [up to 56g] per machine."
Strip out the boards
Place your circuit boards in a glass vessel. In another container, mix two parts hydrochloric acid and one part weak hydrogen peroxide (a concentration of three per cent). Pour this mixture over the circuit boards so they are completely submerged. Wait for a week, giving the vessel a stir every day with a glass or plastic rod.
Over time, the acid will darken and gold flakes will come off the scraps.
Collect the flakes
Pour the mixture through a coffee filter and into another glass container. The gold flakes will be left behind. Pour the remaining circuit-board bits into a deep plastic tray filled with water. Save any pieces with remaining gold for re-dipping. Pour the water through the filter to collect any gold dust, and flush the flakes with water. Wash them with methanol, then again with water to rinse away any residue.
Melt the gold
Wearing protective, flame-resistant clothing, boots and goggles, heat a clay bowl with a blowtorch. Add some borax (available from chemists); this enables the gold to be melted at a temperature lower than 1,064C. When the borax begins to soften, add the gold flakes. Heat until the flakes melt into a gold bead. Now let it cool before chipping the gold out of the re-solidified borax.
