Destress Blasting Experiments at the Pyhaesalmi Mine, Finland

摘要

At the Pyhasalmi Mine, problems associated with high horizontal stress were previously alleviated by excavating a parallel, narrow ore body in the vicinity of the main ore deposit. Destress blasting has later been considered as a potential technique to replace the aforementioned method, not any longer feasible under the prevailing circumstances. Blasting experiments have been carried out at unmined stopes at depths of 645 and 615 meters in order to evaluate the performed blasting rounds in terms of destressing. In the experiments, single rows of bore holes were fired to fracture the ore enclosing the blasted bore holes such that a destressed 'inclusion' would be produced in the remaining stiff ore body. The investigations provided useful information on limiting blast parameters and on the nature and the extent of the blast-induced damage.