Coal has helped power the nation for well over a century, but the US National Energy Technology Laboratory (NETL) researchers are beginning to find another use for this abundant energy source by developing advanced characterisation techniques. Hidden within the black organic rock are tiny quantities of rare earth elements (REEs), and these special elements are widely used in high-tech products, including cell phones, computers, batteries, and lasers. REEs are of significant value to national security, energy independence, economic growth, and the country’s environmental future, but the US currently imports most of its REE supply from off-shore countries.
A promising new way of obtaining REEs domestically begins by analysing and characterising the nation’s supply of coal. REEs are actually not that rare. However, it is unusual to find them in large concentrations (i.e., more than 470 parts per million). That is why developing sophisticated and accurate characterisation techniques is extremely important step in the successful extraction of the valuable elements. NETL has developed techniques for characterising samples both in the field, as well as in the lab, assisting in the demonstration that REE extraction from coal and coal by-products can be technically and economically feasible.
More than 800 field samples have been collected since June 30, 2015 by NETL in-house researchers and personnel from the US Department of Energy’s Office of Fossil Energy. The US Geological Survey and the Electric Power Research Institute have both signed memorandums of agreement with NETL calling for additional collaborative field sampling activity.
REE characterisation efforts by NETL are among the most advanced in the world. Researchers at the Lab employ a variety of techniques, including digestion methods for the accurate determination of trace REE contents by inductively coupled plasma mass spectrometry (ICP-MS). This technique minimises uncertainty in trace REE determination. Recently ICP-MS was also used in an NETL study to determine the concentration of REEs in Alberta, Canada oil sands.
Other NETL characterisation methods include determining cerium (a common REE) distribution in coal combustion byproducts, rock materials, and clays, and using geologic interpretation and elemental characterisation to identify geochemical markers that help in identifying high REE zones. REE-containing minerals were also identified in various coal-related materials using advanced microscopic methods.
NETL’s characterisation efforts are helping to forge a path toward establishing a reliable domestic supply of REEs. The US consumes around 16 – 17 000 t of REEs each year, and this demand could be met by completely extracting REEs from domestic coal and coal byproducts. Evan Granite, NETL engineer, explained: “By tapping into this vast untouched resource of coal and coal byproducts, the United States could benefit from a 1000-year supply of REEs at the current rate of consumption.”
Read the article online at: https://www.worldcoal.com/coal/20072017/netl-researchers-develops-new-way-to-obtain-rees-from-coal/