Computers and other electronic devices contain gold and other precious metals in their circuit boards. As consumers upgrade their electronic gadgets, the precious metals remain trapped in piles of waste. There’s about 0.2 grams (0.007 ounces) of gold in a typical mobile phone handset. Recovery of this gold requires knowledge of basic chemistry and considerable care.
Assemble the scrap circuit boards from computers or phones, memory chips from phones and cameras, and the small components behind LCD screens. Gold in these circuits occurs as a layer over a base metal substrate such as nickel or copper. Separate the gold-plated metal parts in the circuit boards using a magnet. Some gold-plated parts may be inside ceramic components.
Put on the goggles and gloves. Place all of the recovered circuit parts in one of the glass containers. Use another glass container to mix hydrochloric acid and hydrogen peroxide in the proportion 2 to 1. Pour the mixture over the circuit board scrap in the glass vessel. Leave for a week, stirring occasionally with the plastic rod. The acid will turn into a dark solution. The gold will slowly flake from the scrap and accumulate at the bottom of the container.
Separate the gold flakes from the solution by pouring it through a coffee filter. Allow the solution to drip through to a third glass beaker. The gold flakes will remain on the filter. Fill the plastic tray with water to half of its depth, place the remaining circuit board scrap in it and rinse. Pour this water through the filter to extract any remaining gold flakes.
Flush water over the gold flakes to wash them. Pour the methanol through the filter to wash the gold flakes. Wash the flakes again by pouring water over them. Leave the gold flakes to dry on the filter paper.
Put on the overalls and boots. Use the blowtorch to heat up the crucible or clay bowl you are using to melt the gold flakes. Place a teaspoon of borax powder into the bowl and continue heating until it begins to place. Add the gold flakes at this point. Continue heating until the gold flakes melt to form a bead. Cool the crucible and its contents. Use the metal prod to chip out the gold from the solid borax.
Things You'll Need
- Scrap circuit boards
- Protective gloves
- Flame-resistant overalls
- Protective boots
- Hydrogen peroxide
- Hydrochloric acid
- Glass container for circuit components
- Glass beaker for mixing
- Glass beaker for filtering
- Filter funnel and coffee filter
- Plastic rod for mixing
- Plastic tray
- Methanol for washing
- Chemist’s crucible or clay bowl
- Borax powder
- Teaspoon for measuring
- Blow torch
- Well-ventilated working space
Avoid trying this procedure in an enclosed space as the reaction of the scrap with the acid solution will generate toxic fumes.
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