2nd International Workshop in “Geoenvironment and 231 Geotechnics”, September 2008, Milos island, Greece Comparison of lignite reserves estimates in the multilayer deposit of the Amyndeo mine A. Pavlides, D.T. Hristopulos, Z. Agioutantis and K. Kavouridis Department of Mineral Resources Engineering, Technical University of Crete, Hania, Greece Ch. Roumpos Public Power Corporation S.A., Greece ABSTRACT The purpose of this study is to compare estima- tion methods for lignite reserves at the Amyn- deo mine and to provide a map of the estimated thickness of the coal seams. The reserves are first estimated with the method of Voronoi dia- grams, using a group of mirror points to close the polygons around the boundaries of the mine. The second estimation method is based on Or- dinary Kriging using the Spartan variogram model. Finally, the reserves are estimated by the mean lignite thickness value of the drill-hole data Two data sets are investigated. The first one corresponds to an exhausted part of the mine. The derived reserves estimates are com- pared with the actual data obtained by the Pub- lic Power Corporation (PPC) to validate the analysis. The second data set extends over the entire mine, and it is used to derive an approxi- mate estimate of the total lignite reserves. A geostatistical analysis of the total layer thick- ness is performed. An interpolated kriging map of the total thickness variation is produced ac- companied by a map of the kriging uncertainty. 1. INTRODUCTION It is estimated that coal reserves in the world exceed the reserves of oil and natural gas. In Greece, over 60% of the produced electric power is generated by power stations that use lignite as fuel. Three billion tonnes of proven, exploitable lignite reserves are located throughout Greece. Approximately 97 % of the mined lignite is used to supply the lignite power plants with a total installed capacity of 5288 MW. The four operational openpit mines in Western Mace- donia constitute the lignite center of Western Macedonia and produce altogether approxi- mately 52 Mt per year. The open pit mine in the region of Amyndeo (see map in Fig. 1) has been in operation since 1989 and has produced 114 Megatons of lignite until the end of the year 2007 (average produc- tion 8 Mt per year). An extensive system of faults exists in the lignite deposit of Amyndeo. Figure 1: Map of the region around Amyndeo.