The geomechanics of Panasqueira mine, Portugal

Abstract

At Panasqueira mine the mining method for the subhorizontal quartz veins has changed from longwall stopes with partial filling to room and pillar stopes. To obtain with the last referred, under safe conditions, the maximum ore recovery, it became necessary to design different stope patterns based on the knowledge of the geomechanical implications of mining. The paper describes the fundamental part of this knowledge which data collection began more than 25 years ago. The geological and geomechanical characteristics of the rock mass, where low deformable schists are dominant, are referred. The behaviours showed by both the longwall and the room and pillar stopes, as well as its interpretations, are described. The subsidence and also the whole mine stability are analysed on the basis of the actual knowledge and considering the modifications to be implemented on the stoping method.