Assessing the Impacts of In-pit Crushing and Conveying Technology on Optimum Transition Depth from Open-Pit to Underground Mining

The issue of determining the time or depth of the transition from open-pit and underground (OPUG) mining is raised when the deposit can extract a combination of open-pit and underground methods. Technological progress and alterations in geological conditions, exploration information, recovery rate, production capacity, and especially economic parameters such as price and costs can change the time and depth of transition. In deep mines with combined mining potential, optimizing hauling systems as the technological phase with the largest share in the total operating costs is considered as essential from the aspect of achieving the profitability of the mining project. Using traditional haulage systems with trucks, which does not necessarily reduce the costs, is constantly increasing. In such cases, it is necessary to find appropriate alternatives, among which continuous mining systems such as in-pit crushing and conveying (IPCC) stand out. The impacts of applying IPCC in large-scale and deep open-pit (OP) mines with combined extraction potential were evaluated on optimum transition depth (OTD) utilizing a hybrid semi-quantitative approach. The results indicated that employing IPCC technology in deep OP mines with the possibility of combined mining leads to an increase in the OTD and more ore extraction using the OP mining.