Geostatistical Modeling of Overburden Lithofacies to Optimize Continuous Mining in the Ptolemais Lignite Mines, Greece

Lignite production in Greece is implemented mainly by the Public Power Corporation (PPC), with the higher production being in the Lignite Center of Western Macedonia. A continuous surface mining method is used in order to satisfy the high production needs combined with the necessity for selective mining; however, the occasional appearance of hard rock formations in the South Field mine overburdens was critical for the adoption of a discontinuous auxiliary method of rock mass removal, at these places, by explosives and large shovels. Furthermore, to minimize the delay of changing the machinery arrangements when a hard rock formation is met, an a priori knowledge of the spatial distribution of these rock masses would be catalytic. In this work, a plurigaussian simulation model of the overburden geological formations is developed in the South Field mine. This model could be used as a guide to schedule and optimize the overburden removal process. Validation of the model was affected in two ways: by direct comparing estimated to real cross-sections as observed on mine slopes or by correlating PPC’s recorded volumetric results to the average simulated hard rock percentages.