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 10–20% of the harmful process chemicals.
The uniqueness of the method lies in the structure of the biomass. Different filament structures can be formed. So for example, into biological filters. In conclusion that 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. Most importantly using the newest environmentally-friendly extraction reagents. So VTT experiments were possible to recover more than 90% of the metal solution. That’s consequently all dissolved from a circuit board. All as a result with the help of functional ionic liquid. The method facilitates extraction of desired components. Therefore removing them from impurities.
Recovering copper from circuit boards by flotation
The new pre-treatment methods more interestingly developed by VTT. They consequently allow separation of most plastics and ceramics from waste. In VTT experiments, for example and with cell phones crushed. They removed the particles sieved and most noteworthy, separated. They did this magnetically most importantly. Also by eddy current into circuit board fraction.
Treating once more by crushing, sieving and flotation did the trick. It results in a fraction with high concentration of valuable metals. Metals as a result for solution extraction experiments. Flotation raised the copper content of circuit board fraction from 25% to 45. Then all the while gold content increased by a factor of 1.5%!
“Value from Waste” project
The growth of cleantech industry and the rise in the world market prices from the mobile phone scrap. They become consequently metals all from again mobile phone scrap! I mean so much this is a win win win. I mean for concentrated metal production in China.
All most interestingly have resulted in a situation. One in which extraction of several metals from waste streams has become advisable. That’s most interestingly even in Finland. That’s as stricter recycling and utilization rates for electronic waste come due. They are also pushing the development of recycling technologies.
So the purpose of the EU project “Value from Waste” is to develop recovery processes on a more sustainable basis. All consequently to clean materials of impurities. All consequently that reduce opportunities for further use. As well as increase the amount of recovered materials.
The methods developed in the project include mechanical pre-treatment. Also solution extraction, the use of biological methods and optimization of treatment chains. The new treatment methods enable metal refining industry. That’s to use cleaner electronic waste. Most noteworthy and importantly in larger amounts that precious work.
So in the two-year “Value from Waste” project of the research consortium AERTO (Associated European Research and Technology Organizations). Also VTT participated in joint technology R&D. That’s with the following six European research institutes. That’s including Fraunhofer ICT and Umsicht (Germany) and CEA (France). Finally TNO (the Netherlands), SINTEF (Norway), Tecnalia (Spain) and SP (Sweden).
The project was coordinated by SINTEF from Norway.
Flotation
Flotation is also a separation method that separates most noteworthy the hydrophobic particles from hydrophilic particles. Consequently by blowing air into sludge containing both types of particles. So hydrophobic particles are picked up by air bubbles. Finally, then they float to the top of the sludge as froth. Froth as a result that can be skimmed off mechanically.
In conclusion, liquid-liquid extraction is a method that extracts metals at aqueous interface. That’s going selectively into another organic interface immiscible with water. This method, widely used in industrial processes. It enables selective extraction of precious and heavy metals from water. Finally, the metal solution concentrated into an organic interface. It is thus extracted in purer form therefore for further processing.
