More than 1.8bn mobile phones were bought in 2013, but within just a few years, 44% of them could end up “hibernating” in drawers according to research from Hywel Jones, a materials scientist at Sheffield Hallam University. He estimates that the same share will be resold and passed on, 4% will end up in landfills and only 3% will be recycled.

The recycling challenge

Jones unsurprisingly sees major environmental and resource implications in the lack of phone recycling. Each phone contains about 300mg of silver and 30mg of gold. Between now and the end of 2020, 10m tonnes of electronic products will be purchased in the UK. This will include silver, gold and platinum group metals with an estimated total market value of £1.5bn.

Of the 20 different materials in a phone, only a small fraction are ever recuperated, even in the most sophisticated electronics recycling plants such as the huge smelting and electrolysis facility run by metals firm Umicore in Antwerp. In developing countries, where manual disassembly of electronics often takes place, the recovery rate is far lower and comes with the added risk of exposure to hazardous chemicals.

In a bid to head off this growing problem, private technology firms are developing systems to make phone recycling easier, cheaper and less hazardous. Academics meanwhile are hoping that designs for extending the useful life of phones (such as modular phones featuring replaceable components and “skins” that look better with age) can prevent them from being left in drawers in the first place.

Innovations in mobile phone waste

Closed Loop Emotionally Valuable E-waste Recovery (Clever), a UK-based project drawing on experts from several universities, is seeking to develop ground breaking science that could prevent mobile phone waste.

Clever’s prototype phone is based on a “skeleton” to which components such as battery, screen, motherboard, and memory (the “organs”) can be attached and readily replaced if they fail, explains Janet Scott, training director for the Centre for Sustainable Chemical Technologies at Bath University and principal investigator of the Clever project.

The Clever research team is investigating why consumers become attached to their phones. It is also experimenting with materials for the “skin” of the phone that, like leather, look better with age.

Meanwhile for the recycling phase, Scott is developing a plastic material from plant cellulose for the phone’s skeleton, and circuit boards that dissolve into sugars in the presence of engineered bacteria. For the recovery of metals, Scott and her co-workers plan to evaluate the use of ionic liquids, types of salts that may be liquid at ambient temperature, to dissolve specific metals.

The Clever group isn’t the only one developing a modular phone. The search giant Google plans to introduce a prototype modular phone in 2015.

In addition to the move to design a more sustainable phone, there is a flurry of activity to develop more efficient and less environmentally harmful processes for recovering materials from old phones.

The EU’s Associated European Research and Technology Organisations (AERTOs) project, which features six technology firms, has developed a process for recovering materials from old phones that avoids smelting and a nitro-hydrochloric acid solution used in developing countries known as aqua regia.

In the AERTOs process, old phones are dismantled to obtain the printed circuit boards, which are crushed and sieved. Plastics and metals are then separated in water by a process known as flotation, in which bubbles carry plastic particles to the surface to be mechanically skimmed, leaving metals such as copper to be selectively recovered using chemical synthesis.

Gold is dissolved from the residual solids using a chlorine-based process and then filtered in mushroom mats. This so-called biomining approach recovers up to 80% of the gold, says Jarno Mäkinen, research scientist at the Finnish technology institute VTT and a member of the AERTOs team.

Although the approach falls short of the 95% gold recovery rate attained in some smelting plants, the technology works at ambient temperature and avoids smelting facilities’ gaseous emissions. Umicore’s Antwerp facility in contrast runs at more than 1,000C, Mäkinen says.

US-based Entegris, a £400m per year provider of materials to the electronics industry, claims to have developed a closed-loop, acid-based process called eVOLV that can recover 98% of precious metals in electronic waste at ambient temperature and at costs 30–40% lower than smelting. Entegris says the metals it can recover make up more than 99% of the metals in electronics by volume.

“To date, we have agreed to licence our technology to four customers, including two in Asia, which plan to begin operating the first eVOLV plants in 2015,” says Michael Korzenski, the venture’s vice president and general manager.

In the eVOLV process, motherboards from electronic waste are cleaned. Components such as silicon chips are separated, while lead, tin, and silver solder are removed in an acid-based solution.

But whatever potential the emerging technologies might have, traditional smelting firms, such as Umicore, don’t seem too concerned about them. The Belgian company has applied for permission to expand its Antwerp recycling plant by 40% at a cost of £80m to a processing capacity of 500,000 tons per year.

Traditional and emerging recyclers may not see eye to eye on most matters, but they can agree on one thing: there are enough old phones for all comers to recycle – if they can just get them out of the kitchen drawer.

Alex Scott is a journalist covering science and technology topics. This is an article adapted from an original that ran in Chemical & Engineering News

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