The Precious Gold Trapped in E-Waste Can Be Filtered by Fungi

April 16, 2014 Posted by admin

Image: Shutterstock

In 100,000 cell phones, it’s estimated that there is 2.4 kilograms of gold, more than 900 kilograms of copper, 25 kilograms of silver, and more. Depending on the market prices, that’s about $250,000 dollars worth of metals, spread in small amounts across 100,000 nigh disposable devices. To more easily recover those rare, expensive, or potentially harmful materials from cell phones and other forms of e-waste, researchers are looking for help from nature’s own decomposition specialists: fungi.

The VTT Technical Research Centre of Finland has developed a biological filter made of mushroom mycelium mats that could recover as much as 80 percent of the gold in electronic scrap. Gold adhered to the biosorbents, such as fungal and algae biomass, far better than when just chemical preparations were used, which typically recover 10 to 20 percent of the gold.

Recycling electronics is a difficult process. Ruediger Kuehr, the executive secretary of the Solving the E-Waste Problem Initiative, told Motherboard’s Stephen Leahy that each mobile phone is “made up of 40 to 60 different elements,” all of which require processing.

And for myriad reasons, you don’t want those elements to reenter the ecosystem. Some of the elements are heavy metals that could be harmful if they seep into the groundwater; some are environmentally taxing to mine and collect. And some, like copper, silver, and gold, are rare and valuable. In addition to the environmental concerns, recycling phones could keep the price of future electronics down.

As part of the Associated European Research and Technology Organizations’ “Value from Waste” project, the team from VTT engineered biological filters that were aimed at recovering gold in a less environmentally hazardous way that the current methods of smashing, separating, and smelting. Much like how one makes an omelet, though, the first step was still to break all the phones.

“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,” Jarno Mäkinen, Research Scientist at VTT Technical Research Centre, told EE Times Europe.

“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,” Mäkinen said. The researchers didn’t want to go into too much detail on biomass engineering, which relied on organic chemistry and ionic liquids to dissolve the gold particulates and form new complexes, but they did explain that they envision one day creating particular layers designed for recovering particular elements.

The VTT team isn’t the only one tapping nature’s own recyclers. A team of Indian and South Korean researchers researched using biomaterials to filter lead out of wastewater from an e-waste recycling facility.

E-waste is a growing problem, increasing at a rate of 3 to 5 percent a year, which is three times faster than any other solid waste stream. Stemming the tide of electronics flowing into dumps is important, but thus far even e-waste recycling processes are energy intensive and ecologically questionable. But fungi have been in the waste disposal game for a long time. It seems only natural that eventually we’d take a cue from them.

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Thousands lost in alleged Gold Coast Health scam where scrap metal was …

April 15, 2014 Posted by admin

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Filter Recover 80 Percent of Gold in Cell Phone Scrap

April 13, 2014 Posted by admin

Cell phone scrap. Image: Antonin HalasCell 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 percent of the gold in electronic scrap. Extraction of copper from circuit board waste, on the other hand, can be enhanced significantly by floating 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 percent of the gold in the solution adhered to the biomass, compared with only 10–20 percent 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 percent 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 methods developed by VTT allow separation of most plastics and ceramics from waste. In VTT experiments, cell phones were crushed and the particles sieved and separated magnetically and by eddy current into circuit board fraction. Treating once more by crushing, sieving and flotation, resulted in a fraction with high concentration of valuable metals for solution extraction experiments. Flotation raised the copper content of circuit board fraction from 25 percent to 45 percent, while gold content increased by a factor of 1.5.

“Value from Waste” project

The growth of cleantech industry, the rise in the world market prices of metals, and concentration of metal production in China have resulted in a situation in which extraction of several metals from waste streams has become advisable even in Finland. Ever stricter recycling and utilization rates for electronic waste are also pushing the development of recycling technologies. The purpose of the EU project “Value from Waste” was to develop recovery processes on a more sustainable basis, to clean materials of impurities that reduce opportunities for further use, and to increase the amount of recovered materials.

The methods developed in the project included mechanical pre-treatment, solution extraction, use of biological methods and optimization of treatment chains. The new treatment methods will enable the metal refining industry to use cleaner electronic waste in larger amounts.

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