cheminée collectrice

OBS: Méthodes d'exploitation par chambres foudroyées (...) a) Les travaux préparatoires (...) comprennent les creusements successifs suivants: (...) des cheminées collectrices issues de cette voie de roulage (...)

OBS: This is a short raise driven from a haulage level, which is belled out at the top to direct broken ore to the chute or drawpoint established at the level. A series of boxholes may be connected together at their tops to form a continuous undercut of an area to be mixed and allow intimate control of broken ore removed from the stope.