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New MIT process may lessen recycling, and rare-earth separation,” says
rare earth metals’ shortage Stinn. “Those are processes that make
materials for sustainability applications,
CAMBRIDGE, Mass. — New processing but the processes themselves are very
methods developed by MIT research- unsustainable.”
ers could help ease looming shortages
of the essential metals that power Growing demand
everything from phones to automotive The findings offer one way to alleviate a
batteries, by making it easier to sepa- growing demand for minor metals like co-
rate these rare metals from mining balt, lithium, and rare earth elements that
ores and recycled materials. are used in “clean” energy products like
electric cars, solar cells, and electricity-
Selective adjustments generating windmills.
Selective adjustments within a chemical
process called sulfidation allowed profes-
sor of metallurgy Antoine Allanore and his
graduate student Caspar Stinn to success-
fully target and separate rare metals, such
as the cobalt in a lithium-ion battery, from
mixed-metal materials.
As they report in Nature, their processing
techniques allow the metals to remain in
solid form and be separated without dis-
solving the material. Pictured are rare earth oxides of neodymium, praseodym-
ium, and dysprosium – all critical components for magnets
– that have been processed with sulfidation technology.
This avoids traditional but costly liquid The violet regions are neodymium-rich sulfide, the green
separation methods that require signifi- regions are praseodymium oxysulfide, and the orange re-
gions are dysprosium rich sulfides and oxysulfides. (MIT)
cant energy. The researchers developed
processing conditions for 56 elements and Unsustainable applications
tested these conditions on 15 elements. “Those are processes that make materi-
als for sustainability applications, but the
Reduced capital costs processes themselves are very unsustain-
Their sulfidation approach, they write in able,” he added.
the paper, could reduce the capital costs of
metal separation between 65 and 95 per- For more than a decade, the Allanore
cent from mixed-metal oxides. group has been studying the use of sulfide
materials in developing new electrochemi-
Their selective processing could also re- cal routes for metal production.
duce greenhouse gas emissions by 60 to
90 percent compared to traditional liquid- Sulfides are common materials, but the
based separation. MIT scientists are experimenting with
them under extreme conditions like very
“We were excited to find replacements high temperatures — from 800 to 3,000
for processes that had really high lev- degrees Fahrenheit — that are used in
els of water usage and greenhouse gas manufacturing plants but not in a typical
emissions, such as lithium-ion battery university lab. next page
