"Further crushing, sieving, and flotation (a separation method that separates hydrophobic particles from hydrophilic particles by blowing air into the sludge) resulted in a fraction with high concentration of valuable metals for solution extraction experiments. The researchers say their flotation technique raised the copper content of the circuit board fraction from 25% to 45%, while gold content increased by a factor of 1.5.
"Because it is difficult to remove the components from the circuit boards, the first step in most recycling processes is to crush everything into particulates and that's how we start, too," explains Jarno Mäkinen, research scientist at VTT. "But then, using non-toxic water-based solutions, we have managed to engineer mycelium-based biomass that acts as a biosorbent specifically targeted at gold complexes."
Using biosorbents such as fungal and algae biomass, the Finnish lab demonstrated that more than 80% of the gold in the solution adhered to the biomass, compared with only 10% to 20% of gold recovery when using most commonly used harmful chemical preparations."
This like the current methods will require an industrial scale (the average Joe isn't going to crush his old cell phone or RAM and get any gold or silver), but its not a bad deal if you can extract some of these metals in an environmentally friendly way.