Sodium removal from Wucaiwan coal by microwave treatment

In order to study the effect of microwave treatment on the sodium removal from the Wucaiwan coal,Wucaiwan coal was waterwashed in laboratory microwave oven and high-pressure reactor,and the coal sample prepared by water-washing in high-pressure reactor was dried by microwave drying and traditional air drying method,respectively.The sodium content of the raw and treated coal samples was determined by an inductively coupled plasma atomic emission spectroscopy.The results indicate that the sodium contained in Wucaiwan coal is mainly in the forms of water-soluble sodium.With the increase of temperature,the efficiency of sodium removal from the coal using microwave water-washing followed by traditional air drying increased and reached 51.6% at 200 ℃.Compared with the electric heating water washing method,the microwave treatment has the higher efficiency of sodium removal.The sodium content of the electric heating waterwashed coal sample can be further decreased by the subsequent microwave drying.The best microwave drying time (at 200 ℃) for the sodium removal from the coal treated by the electric washing is 10 min.Compared with the hot air drying,a higher efficiency of sodium removal was obtained by the microwave drying after the electric heating water washing (200 ℃) in a short time.