Trade name for a dense-medium washer for treating coal lump size down to about 1/8 in (3.2 mm). It comprises a shallow circular tank with a flat base and a conical inner shell containing the driving mechanism. The clean coal floats and passes over a weir while the shale sinks to the bottom and is conveyed to an outlet chute. Its capacity ranges from 2141 about 50 st/h (45.4 t/h) to over 500 st/h (454 t/h), depending on the size of the vessel.