A feasibility study of waste transportation through existing underground excavations in open pit Angouran mine

Annual increasing depth in Angouran Lead & Zinc open pit mine, along with the technical, topographic and geomechanical limitation causes an increase in transportation costs and a reduction in efficiency. The existence of underground excavations in the high grade sulfurous zone promotes a research on the identification and analysis of applicable technical solutions for reducing the transportation costs in the open pit mining using existing underground excavation. For this purpose, at first, the existing underground excavation network was modeled using Micromine software. Then, the modelling of open pit ultimate pit limit was performed by Datamine & NPV scheduler softwares to determine the depth and the range of expansion of the cavity. By adapting this model with underground network, seven scenarios have been specified to to connect open pit limit and underground network. At the next step, superior scenarios were presented based on excavation tonnage, operating cost and construction duration criteria, in which scenario 6 was offered as the preferred scenario. In this scenario, the connection of pit limit and underground space was performed with 3 excavations. The first excavation is the inclined shaft connecting the upper tunnel to elevation 2840 for open pit waste material handling. At the next step, excavation of a drift from bench 2804 to middle of this shaft was performed. In order to get access to the lower elevations, an underground zigzag ramp ramified from the main ramp will connect to elevation 2768. The operation of this scenario brings aboutan improvement to the supplying of filling materials to the underground operating spaces.