Researchers Use Ultrasound to Recover Gold from Electronic Scrap

The last few months have been ripe with reports on new research related to material recovery from electronic scrap (commonly referred to as “e-scrap” or “e-waste”), as highlighted in a previous post. I’ve learned of yet another exciting innovation in this field, thanks to a feature written by Jared Paben in the latest edition (4/19/18) of E-Scrap News.

As Paben reports, researchers from Sandia National Laboratories have developed a method to use ultrasonic waves, coupled with surfactants, to cheaply and efficiently recover gold from scrap electronics. Their experiments involved application of two different surfactants to the surface of a cell phone SIM card, which was then submerged in water. Ultrasonic waves were applied, which imploded micro-bubbles on the SIM card’s surface. Upon collapse of these micro-bubbles, micro-jets ejected gold nanoparticles from the card’s surface, and the nanoparticles were captured and stabilized by the surfactants.

According to the research group’s paper, published in the journal Small on 3/24/18), this mechanical method may not only present an effective way of reclaiming gold and other metals from electronic scrap, but could potentially be used to manufacture gold nanoparticles from native gold metal directly upon recovery from mining, which they say “may represent the greenest possible approach to nanoparticle synthesis.” (Citation: J. Watt, M. J. Austin, C. K. Simocko, D. V. Pete, J. Chavez, L. M. Ammerman, D. L. Huber, Small 2018, 1703615. https://doi.org/10.1002/smll.201703615)

You can read more about this research in a 4/3/18 article from New Scientist.

To learn about cavitation and cavitation bubbles, the phenomena which allow this mechanical process to work, see https://www.nsf.gov/news/special_reports/science_nation/cavitationbubbles.jsp and https://en.wikipedia.org/wiki/Cavitation.

For more information on gold in electronics, see How Much Gold is in Smartphones and Computers? and Uses of Gold in Industry, Medicine, Computers, Electronics, Jewelry.

To learn about the properties and applications of gold nanoparticles, see https://www.sigmaaldrich.com/technical-documents/articles/materials-science/nanomaterials/gold-nanoparticles.html.

Further Developments in E-Waste Recycling

In a previous post, we discussed how researchers at the Illinois Sustainable Technology Center (ISTC), on the campus of the University of Illinois at Urbana-Champaign have developed an energy-efficient, non-toxic, nondestructive chemical process to recover polymers from the complex plastic blends found in items like cellphone cases.

But that’s not the only exciting news this Earth Month related to innovations in reclaiming materials from electronic scrap (commonly referred to as “e-waste”). In a GreenBiz article dated 4/18/18, Heather Clancy highlights an electrochemical process developed by Canadian venture EnviroLeach Technologies, which is similar to the conventional method of leaching gold and other metals out of ores, concentrates and tailings. The difference is that “instead of using cyanide, the patent-pending formula uses five non-toxic, FDA-approved ingredients that are combined with water at ambient temperatures.’The process does not require pressure, elevated temperatures, complex process circuits, intensive gas monitoring or costly detoxification systems,’ explained EnviroLeach on its website.” Read the full story on the GreenBiz web site. You can also check out the EnviroLeach web site for further information. This development is particularly encouraging considering a recent article from Environmental Leader reporting that n a study by researchers from Tsinghua University in Beijing and Macquarie University in Australia, which suggests extracting metals from e-waste costs 13 times less than mining ore. Perhaps the new process will make the economic benefit even more striking, while minimizing environmental impacts.

Elsewhere in Canada, researchers at the University of British Columbia “have perfected a process to efficiently separate fibreglass and resin – two of the most commonly discarded parts of a cellphone – bringing them closer to their goal of a zero-waste cellphone.” As UBC News reports, “Most e-waste recycling firms focus on recovering useful metals like gold, silver, copper and palladium, which can be used to manufacture other products. But nonmetal parts like fibreglass and resins, which make up the bulk of cellphones’ printed circuit boards, are generally discarded because they’re less valuable and more difficult to process. They’re either fed to incinerators or become landfill, where they can leach hazardous chemicals into groundwater, soil and air.” But UBC mining engineering professor Maria Holuszko, along with PhD student Amit Kumar, has developed a process using gravity separation “and other simple phycial techniques to process cellphone fibreglass and resins in an environmentally neutral fashion.” The next step in pursuing this innovation is developing a large-scale commercial model of the process with their industrial partner and recycling company Ronin8. Read the full UBC article on the UBC News web site.

Read more at https://ifixit.org/recycling on why electronics recycling, though of course important, should not be considered the answer to the problem of ever-growing amounts of e-waste, due to the difficulty in reclaiming materials (eased slowly by new innovations like the ones described above) and energy use. While these developments in electronic scrap recycling are heartening, it’s important to remember to keep your electronics in service as long as possible through repair and upgrades, and when you no longer want or need a functioning device, sell or donate it so someone else can use it. Recycling should only come at the ultimate end of a device’s useful life.

Amnesty International Reports on Child Labor in Cobalt Battery Supply Chain

On November 15, 2017, Sustainable Brands reported that Amnesty International had released a new report revealing that tech industry giants such as Microsoft, Lenovo, Renault and Vodafone aren’t doing enough to keep child labor out of cobalt battery supply chains in Democratic Republic of Congo (DRC) and China. “The findings come almost two years after Amnesty exposed a link between batteries used in their products and child labor. Time to Recharge ranks industry leaders, including Apple, Samsung SDI, Dell, Microsoft, BMW, Renault, Vodafone and Tesla according to improvements to their cobalt-sourcing practices since January 2016. The 108-page report revealed that only a handful of companies made progress, with many failing to take even basic steps, such as investigating supply links in the DRC. The report’s publication is timely, arriving just months after the UK government announced plans to ban new petrol and diesel cars and vans from 2040, which would ultimately lead to higher demand for cobalt batteries. This last point is particularly problematic as recent reports have revealed that cobalt resources are on the decline, despite demand growth predicted at 500 percent.”

See http://www.sustainablebrands.com/news_and_views/walking_talk/sustainable_brands/amnesty_international_reveals_tech_industry_giants_fa for the complete article on the Sustainable Brands web site.

To download the report itself, Democratic Republic of the Congo: Time to recharge: Corporate action and inaction to tackle abuses in the cobalt supply chain (15 November 2017, Index number: AFR 62/7395/2017), see https://www.amnesty.org/en/documents/afr62/7395/2017/en/.

Amnesty International logo, with the wordmark on a yellow background beside a stylized image of a lit candle entwined with barbed wire

Green Chemistry and Biomimicry: A More Sustainable Process for Metal Extraction

A team of chemists from McGill University in Montreal, Quebec, Canada, and Western University in London, Ontario, Canada, have developed a way to process metals without toxic solvents and reagents. Their innovation could help reduce negative environmental impacts of metal extraction from raw materials and electronic scrap.

As reported by McGill, “The system, which also consumes far less energy than conventional techniques, could greatly shrink the environmental impact of producing metals from raw materials or from post-consumer electronics…In an article published recently in Science Advances, the researchers outline an approach that uses organic molecules, instead of chlorine and hydrochloric acid, to help purify germanium, a metal used widely in electronic devices. Laboratory experiments by the researchers have shown that the same technique can be used with other metals, including zinc, copper, manganese and cobalt.”

The development is an interesting example of biomimicry. Germanium is a semiconductor not found in substantial quantities in any one type of ore, so a series of processes are used to reduce mined materials with small quantities of the metal to a mixture of germanium and zinc. Isolation of germanium from the zinc in this resulting mixture involves what one of the researchers called “nasty processes.” For an alternative less dependent upon toxic materials and energy use, the researchers found inspiration in melanin, the pigment molecule present in skin, hair, and irises of humans and other animals. Besides contribution to coloration, melanin can bind to metals. The researchers synthesized a molecule that mimics some of melanin’s metal-binding qualities. Using it they were able to isolate germanium from zinc at room temperature, without solvents.

Image of a shiny, silver-grey metallic rock
Image of germanium by W. Oelen, CC BY 3.0

As the McGill article states, “The next step in developing the technology will be to show that it can be deployed economically on industrial scales, for a range of metals.”

Read the full story, published June 7, 2017 by the McGill Newsroom at https://www.mcgill.ca/newsroom/channels/news/more-sustainable-way-refine-metals-268517.

See also “A chlorine-free protocol for processing germanium,” Martin Glavinović et al., Science Advances, 5 May 2017. DOI: 10.1126/sciadv.1700149 http://advances.sciencemag.org/content/3/5/e1700149

To learn more about germanium and its applications (including fiber-optics, infrared optics, solar electric applications, and LEDs), see the Wikipedia article on germanium at https://en.wikipedia.org/wiki/Germanium.