Geomechanical aspects in Alimak stoping at Barrick's Bulyanhulu Mine

Abstract

Alimak stoping is a modified version of the longhole mining method applied to steep and narrow deposits with competent hanging and footwalls. As it adopts an Alimak raise along the hangingwall for access to perform drilling and blasting, personnel are required to work inside the confined space and this poses unique geomechanical challenges. Barrick's Bulyanhulu Mine (Bulyanhulu) located in northwestern Tanzania extracts selected areas using Alimak stoping. More than 12 Alimak stopes have been mined in four separate mining blocks down to 1000 m below surface. A large deep mining zone is currently planned for extraction using this method. A geomechanical assessment has been conducted to evaluate the proposed application. In this paper, practices of Alimak stoping at Bulyanhulu are presented. Based on the geomechanical assessment of a deep mining block, guidelines are developed for Alimak stoping in multiple lifts using a primary and secondary sequence. Learnings from Alimak stoping and findings from the geomechanical assessment will help future mining at Bulyanhulu and also mines under similar conditions.