trough washer

trough washer

[′trȯf ′wäsh·ər]
(mining engineering)
A sloping wooden trough, 1½ to 2 feet wide, 8 to 12 feet long, and 1 foot deep (about 50 by 300 by 30 centimeters), open at the tail end but closed at the head end; it is used to float adhering clay or fine stuff from the coarser portions of an ore or coal.