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Conference Proceedings

The Australasian Ground Control Conference An ISRM Regional Symposium (AusRock Conference) 2022

Conference Proceedings

The Australasian Ground Control Conference An ISRM Regional Symposium (AusRock Conference) 2022

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Ore recovery on a room and pillar zinc mine

Morro Agudo is an underground zinc and lead mine owned by Nexa Resources. The mine uses room and pillar as the main mining method. The recovery of pillars as well as the opening of new excavations using sublevel stoping as mining method has been studied. On some occasions, the need to recover pillars and open a stope by using the sublevel method happens in a region that is already excavated or in deeper areas than those mined so far. These changes represent a major geotechnical challenge due to the complex openings of the mine and interaction between two different mining methods. Historically, geotechnical mapping, kinematic analysis and a 2D numerical model were used to evaluate the new mine openings, and in 2021, 3D numerical model was introduced, which enabled global and local assessment of new excavations impact and the stability of openings after recoveries. The 3D model, made with MAP3D, is used to evaluate each pillar to be recovered, considering the spans of the resulting openings, the ideal sequencing of removal to maintain stability, in addition to the impact and geometry of the pillars left in the chambers. Pillar recoveries done in 2021 and the impact of it on the pillars left were the sources of the back analysis to calibrate parameters inputted on numerical model to assess recovery on new chambers and Phyllite has been considered into the model and it has been a source of instability due to its parallel position to roof of room and pillars and stope hanging walls
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  • Ore recovery on a room and pillar zinc mine
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  • Published: 2022
  • Pages: 1
  • PDF Size: 0.092 Mb.
  • Unique ID: P-02426-V0F3K6

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