Design of the Opencast Coal Mine Drmno Dewatering System

Abstract

Development of mining in the opencast mine Drmno from Kostolac basin in Serbia is carried out in the increasingly complex geological and hydro-geological conditions with the decline of the coal seams to the alluvial part of Europe’s largest river Danube. Greater depth and inflow of groundwater significantly increase costs for dewatering facilities construction with the requirement for optimizing of this more and more important surface mining process. Making decision on screen construction in the opencast mine with redesign of line wells parameters for the defence against groundwater, in addition to geology and hydrogeology exploration activities, analyzing the elements of the opencast mining systems and a number of working environment parameters with the development of the hydrodynamic model requires necessary review of economic and environmental effects. A detailed techno-economic analysis has been done in order to demonstrate technological justification and economy of screen construction as the system for protection against groundwater in the opencast mine. The defence of the opencast mine against the groundwater without the construction of screen causes construction of several dewatering wells and lines with increased pumping capacities by the end of deposit mining. On the other hand, screen construction means big initial investments but with a smaller number of dewatering wells with reduced capacities, lower cost of electricity and larger reliability of the system operation in the long period until the closure of the opencast mine. Estimates of environmental impact and efficiency comparison between these systems options for protection against of groundwater have been done. DCF analysis has shown that the long-term averaged costs for opencast mine Drmno dewatering against groundwater per ton of coal are approximate for the both system options. Final decision on the approval of the combined dewatering system with a reduced number of dewatering wells and screen construction has been caused by the system reliability and environmental effects related to the impact on the groundwater level outside of the opencast mine boundaries and safer operation of the hydro power plant Djerdap system on the Danube River.