Numerical Modelling Study of Low-rise Mining at the Tara Mine

Sammanfattning: The following report is the results of a master thesis project performed on the behalf of Boliden Tara Mines. The work includes a numerical modelling study with the main purpose to evaluate the room- and pillar stability for the mining method "drift-and-slash" mining currently used in the Tara Mine when mining in thin, low-rise lenses. Also, the potential of applying the "drift-and-fill" mining method was studied during the project. The numerical modelling work was performed both two-dimensionally and three-dimensionally, using the Itasca software FLAC and FLAC3D.  The study resulted in recommendations regarding the room- and pillar dimensions, mining sequence, rock support, mining method and further studies. It was concluded that the currently used room- and pillar dimensions could be altered to increase the extraction ratio and that the mining sequence and rock support should be determined depending on the room- and pillar dimensions. Also, that it could be possible to change from the drift-and-slash method to the drift-and-fill method from a stability perspective. Lastly, it was recommended to further study the rock strength and to monitor the pillar behaviour.