Effect of microwave heating on the physical and petrographic characteristics of a UK coal

This investigation presents the findings of an initial study into whether the grinding resistance of coal can be reduced with microwave pretreatment without significantly altering the fundamental properties of the coal. A U.K. steam coal was sieved into seven size fractions and then treated with high-electric-field-strength microwave energy for a short duration to investigate how the grinding resistance changed, in comparison to that of untreated coal, and how the chemical and petrographic compositions were altered after exposure. Short exposures to microwave energy (on the order of seconds) gave significant increases in grindability, and these changes were related to particle size. The effects on petrographic and chemical characteristics were considered to be negligible. Conclusions are made regarding the scale-up of this technology and the likely impact of microwave treatment in the electrical power industries.