Coal to graphite using microwave oven, scientists show how

A demonstration conducted by an international team of scientists showed that pulverised coal powder could be converted into high-value nano graphite within 15 minutes.

The team of scientists led by TeYu Chien from the University of Wyoming, Department of Physics and Astronomy, in a study published in the journal Nano-Structures & Nano-Objects, explained how they created an environment in a microwave oven to successfully convert raw coal powder into nano graphite, which is used as a lubricant and in items ranging from fire extinguishers to lithium-ion batteries.

In their view, this “one-step method with metal-assisted microwave treatment” is a new approach that could represent a simple and relatively inexpensive coal-conversion technology to make proper use of Wyoming’s Powder River Basin coal.

According to the scientists, while previous research had shown that microwaves could be used to reduce the moisture content of coal and remove sulphur and other minerals, most of the methods required a specific chemical pretreatment of the coal. However, in their experiment, the only treatment performed was to grind raw Powder River Basin coal into powder.

Then the powder was placed on a copper foil and sealed in glass containers with a gas mixture of hydrogen and argon, before being put in a microwave oven.

By cutting the copper foil into a fork shape, sparks were induced by the microwave radiation, generating extremely high temperatures, crossing 1800 degree Fahrenheit within a few seconds, as reported by sources.

The coal powder was then transformed into polycrystalline graphite by the high temperatures, with the hydrogen gas and copper foil also contributing to the process.

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The group – which also has researchers from China, New York and Nepal reportedly believes that this new coal conversion process could be refined and performed at a greater scale to yield both higher quality and quantity of nano-graphite products.