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Gold from the trash |

Gold from the trash |

Only a fraction of the gold in e-waste is recovered – an illustration that we are still miles away from a circular economy.

Gold has fascinated humanity for at least 6,000 years, and since then more than 200,000 tons of gold have been mined – that's the equivalent of a cube with a side length of 22 metres. More than half of annual gold production is processed into jewelry, a good third is held by central banks and investors as collateral, and about nine percent (or 300 tons) is needed as essential components of electronic devices (particularly circuit boards and tracks). ).

Depending on the type of deposit, 200 kilos to 1.7 tons of rock must be extracted and processed to produce one gram of gold – using a lot of energy and questionable chemicals. However, we rarely use any other source of gold: more than 50 million tons of electronic waste are currently generated worldwide every year, and this trend is rising rapidly; But only 17 percent of it is recycled. This high-tech waste contains countless valuable materials, in very high concentrations: for example, the gold content in smartphones, which is about 150 milligrams per kilo, is 100 times higher than in natural deposits.

There are many processes for extracting precious metal from waste – such as chemical leaching, membrane processes, thermal processes, photocatalysis, biological processes, etc. – which are constantly being developed. As researchers led by Jinsong2) On the other hand, it is cheaper by a factor of 20 (Total Ecology 916, 170154).

Of course, the question arises as to why all electronic waste has not been treated for a long time. Part of the answer is that electrical devices are an extremely complex mixture of countless materials: a smartphone, for example. B. It consists of more than 1,000 substances, including 53 minerals – and separating them cleanly is technologically very difficult. Even more alarming is that there is a lack of basic requirements for sensible recycling – from functioning collection systems to organized recycling chains.

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This is an example of how difficult it is to say goodbye to our current “linear” approach to materials (production – use – disposal) and build a more sustainable circular system instead.

The author headed the “Press” research department and is now a scientific communicator at the American Institute of Technology.

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