Mobile phone scrap can contain precious metals, such as gold and copper. VTT Technical Research Centre of Finland has developed a biological filter made of mushroom mycelium mats enabling recovery of as much as 80% of the gold in electronic scrap. Extraction of copper from circuit board waste, on the other hand, can be enhanced significantly by flotation the crushed and sieved material.
Although research into the biological methods is active, these are still rarely used in metal recovery chains. In a European "Value from Waste" project, VTT developed both biological and mechanical pre-treatment methods for more efficient recovery of precious metals from electronic waste. Other methods developed by researchers included recovery of gold from dissolved materials by biosorption and extraction, using as few harmful chemicals as possible.
Fungi catch gold and filter out impurities
VTT has developed a method that harnesses biosorbents, such as fungal and algae biomass, for the recovery of precious metals converted to a solution. In VTT tests, more than 80% of the gold in the solution adhered to the biomass, compared with only 1020% of the harmful process chemicals.
The uniqueness of the method lies in the structure of the biomass. Different filament structures can be formed, for example, into biological filters, which makes further industrial processing of precious metals easier.
Gold also separates well in liquid-liquid extraction
The project developed a method with high extraction capacity for gold recovery, using the newest environmentally-friendly extraction reagents. In VTT experiments, it was possible to recover more than 90% of the metal solution dissolved from a circuit board with the help of functional ionic liquid. The method facilitates extraction of desired components from impurities.
Recovering copper from circuit boards by flotation
The new pre-treatment method
|Contact: Olli Salmi|
VTT Technical Research Centre of Finland