Unloading scheme of Angooran mine slope by discrete element modeling

•Angooran lead and zinc open-pit mine is one of the most economical lead and zinc mines in the world.•Modeling of the sliding mass in Angooran mine and then unloading it in five stages have been done.•During the unloading, maximum velocity and displacement among the particles are obtained.

Angooran mine is located in the northwest of Iran and has experienced a large scale slope failure in northern wall. Sliding mass volume occurred in Angooran mine was about 12×106 m3, i.e. 25×106 t. The sliding mass moved about 45 m vertically and 100 m horizontally. For managing this sliding and keeping mine alive simultaneously, it was necessary to monitor sliding mass and modeling its behavior. Because of velocity value and volume of sliding mass should not be exceeded a certain limit and also opportunities for mining have to be surveyed, velocity and displacement have been monitored during the unloading stages of sliding mass. Velocities cannot be zero, but with prediction of velocity and displacement of sliding mass, the scheme of unloading can be evaluated. In this paper, modeling of the sliding mass in Angooran mine and then unloading it in five stages have been done. During the five stages of unloading, maximum velocity and maximum displacement among the particles are obtained. The modeling results indicate that the maximum velocity occurred in the second stage of unloading mass in the crushed zone and maximum displacement occurred in the third stage of unloading mass in the sliding zone (0.39 m/day and 40.14 m, respectively).