Coal mining - Wikipedia, the free encyclopedia In Australia, "colliery" generally refers to an underground coal mine. ...Coal- cutting machines were invented in the 1880s. Before ... Many coals extracted from both surface and underground mines require washing in a coal preparation plant.
A coal preparation plant ... A simple stockpile is formed by machinery dumping coal into a pile, either from dump trucks, ... The procedures for this analysis are detailed in Australian Standard AS 4156.1 – 1994 "Coal preparation — Higher rank coal — Float and sink testing".