From Longman Business Dictionary
coalfacecoal·face /ˈkəʊlfeɪsˈkoʊl-/ noun [countableC usually singular]1the part of a coal mine where coal is cut from the earth 2at the coalface British EnglishBrE doing work and gaining experience yourself, rather than studying or readinghis experiences in dealing with boards and managers at the coalface in retail banking