The effect of microwave radiation on coal grindability

Coals of various ranks were exposed to microwave radiation to quantify the effect on grindability. Reductions of up to 50% of the relative grindabilit y of the coals were reported after 5 min microwave exposure. These are beli eved to be a combination of fracture mechanisms, inherent moisture within t he coal structure changing phase under considerable pressure and differenti al expansion by gangue mineral components. The overall effect of microwave radiation on the coal calorific value was minimal and compares equally to c onventional drying techniques. Future work will include scaling up to pilot plant level (50-100 kg/h) to allow an accurate techno-economic assessment of the process. (C) 2000 Elsevier Science Ltd. All rights reserved.