Optimization of Main Technological Parameters Afferent for the Mining Methods with Undermined Coal Bank Applied for the Conditions of Thick Coal Seams in Jiu Valley

Utilization of mining methods with undermined coal bank in the case of thick coal seams in Jiu Valley coal basin has lead to the increase of efficiency obtained and to significant decrease of production costs, but the establishment of coal fields has been made without performing an accurate analysis regarding the influence of main technological parameters’ variation of this method (length of face line ,,lab”, length of face field ,,lp”, and the thickness of undermined coal bank ,,hb”) onto the achieved technical and economical indexes.