This ‘one-step method of metal-assisted microwave treatment’ is a new approach that they say could be a simple and relatively inexpensive coal conversion technology to make good use of the Powder River Basin coal in Wyoming.
According to the team led by TeYu Chien of the University of Wyoming, while previous research has shown that microwaves can be used to reduce the moisture content of coal and remove sulfur and other minerals, most such methods require a specific chemical pretreatment of the coal. In their experiment, however, the only treatment was to grind raw Powder River Basin coal into powder.
That powder was then placed on copper foil and sealed in glass containers with a gas mixture of argon and hydrogen before being placed in a microwave oven.
“By cutting the copper foil into a fork shape, sparks were caused by the microwave radiation, which within a few seconds generated an extremely high temperature of more than 1800 degrees Fahrenheit,” Chris Masi, lead author of the article, said in a media statement said.
The high temperatures then converted the coal powder into polycrystalline graphite, and the copper foil and hydrogen gas also contributed to the process.
The group – which also includes researchers from New York, Nepal and China – believes that this new method of coal conversion can be refined and carried out on a larger scale to produce a higher quality and quantity of nano-graphite material.