Researchers at Rice University devised a technique that uses rapid heating to recover 90% of a scarce metal from discarded electronics plastics.
Here's what to know
The method, called isothermal-clamped flash joule heating, uses brief electrical heating to separate antimony from flame-retardant plastics, according to Interesting Engineering.
A collection area captures the antimony as it condenses after evaporation. The process reclaims material that would otherwise be discarded.
The plastic remained within the 392-932-degree range for just 9.4 milliseconds, giving hazardous organic bromide compounds little opportunity to form. Unwanted compounds can develop when heating allows more time for the material to change form.
"Conventionally, heating the plastic releases the antimony in a volatile and difficult-to-collect form as well as creating and releasing hazardous organic bromide compounds," Leo Haoxin Ye, the paper's first author, said in a news release.
More background
In electronic devices, plastic casings reduce the risk of electrical fires. Their flame-retardant properties come from antimony.
TCD Picks » Quince Spotlight
💡These best-sellers from Quince deliver affordable, sustainable luxury for all
Nearly 39% of global antimony supplies go toward making flame-retardant plastics, the majority of which eventually reach landfills, according to Interesting Engineering. Worldwide production of flame retardants is expected to total 82 million metric tons by 2030, and electronic waste adds tens of millions of tons annually, per the release.
Recovering antimony could conserve dwindling mineral reserves.
Aside from the troublesome byproducts associated with conventional heating, other recovery methods rely on powerful acids, organic solvents, or multistep treatments, which Ye called risky and less practical.
What's being done?
The Rice team adapted this flash-heating approach to recover antimony and capture bromide.
Researchers held ground-up plastic between two electrically heated carbon-paper sheets and applied several ultrafast heating pulses. The flame-retardant plastic waste used in the experiment came from the researchers' own laboratory.
Outside of reclaiming antimony, the process turned 83% of the waste's bromide into hydrogen bromide, a useful industrial chemical.
Tests on housings for power supplies, circuit boards, and electrical connectors succeeded across several varieties of flame-retardant plastic.
The results did not address commercial-scale deployment or consumer cost savings.
The team concluded that "isothermal-clamped flash joule heating could improve the speed, safety, and practicality of antimony recovery from discarded flame-retardant plastics."
Where can I learn more?
Recovering antimony from electronics is one way to keep valuable materials out of landfills.
• Aging wind turbines and solar panels are creating new e-waste challenges for the renewable-energy sector.
• In England, repair cafés fixed 50% of electronics, while only 2% of recycled electronics were reusable.
• In China, EV battery recyclers are running at full capacity as smelting demand rises.
• In Covington, Georgia, a startup is working to revive a battery-recycling plant amid lithium supply concerns.
• U.S. solar recyclers are recovering aluminum and silver, but low-silver panels are threatening their business model.
Get TCD's free newsletters for easy tips, smart advice, and a chance to earn $5,000 toward home upgrades. To see more stories like this one, change your Google preferences here.
