To remove muck such as pebbles conveyed together with coal on a conveying line for conveying coal from a coal silo to a boiler.

A belt 6 of a removing belt conveyor 5 is disposed between a positive electrode plate 2 and a negative electrode plate 3 and moved in contact with the plate surface of the positive electrode plate 2 and the plate surface of the negative electrode plate 3. When a stored material M is supplied between the positive electrode plate 2 and the negative electrode plate 3 from a supply port 4, positively charged coal M1 is attracted to the negative electrode plate 3, and negatively charged muck M2 is attracted to the positive electrode plate 2. These coal M1 and muck M2 are discharged from a coal discharge port 8b and a muck discharge port 8a respectively through the belt 6.