A review of microwave coal processing

This paper reviews the application of microwave energy in coal processing and utilisation. It brings together all of the published work on the microwave treatment of coal. The majority of the work was carried out at lab scale, although a few processes have made it to pilot or even industrial scale. The processes with more immediate promise for scale-up are identified, as are those that require further laboratory scale experiments to establish whether microwave processing should be pursued at a larger scale. The importance of dielectric properties of the materials to be processed is emphasized, and the reasons behind the need for a multi-disciplinary approach to the design and operation of electromagnetic experiments are explained. Microwave coal processing is a diverse area, which has the potential to aid in coal upgrading, cleaning and comminution, thus improving efficiency and reducing harmful emissions of coal usage. Other promising research areas include the investigation of microwave processing for coking, liquefaction, enhancing fluid flow in coal beds and coal characterisation. The paper concludes by discussing the barriers to scale-up that these processes face.