McNally-Norton jig

McNally-Norton jig [mik′nal·ē ′nȯrt·ən ′jig]

(mining engineering)

A device used to clean raw coal by carrying it to a wash box and using water whose level rises and falls as a result of air pulsations; the incoming coal is suspended by the pulsating water while the heavier refuse sinks to the bottom; the coal then spills over into the next wash box where the process is repeated, and the clean coal is discharged by the dewatering screens.