A review of the current and future conditions of combined open-pit and underground mining around the world

Many mineral deposits start from the surface or near the surface and have a significant depth extension that has the potential to be mined by a combination of open-pit and underground methods in a sequential (non - simultaneous) and simultaneous manner. The most critical issue related to this type of deposits is determining the optimum transition depth (OTD) from open-pit to underground mining. The main goal of this research is to investigate the trend of using combined mining options, the advancements of the methods of determining the optimum transition depth, and overview of the mines with the potential of combined mining. In this research, the basics related to the approaches and methods of determining the optimum transition depth have been discussed. Different modes of combining open-pit and underground mining have been investigated. In addition, to review the current and future conditions of combined mining around the world, some of the most critical cases of using combined mining have been evaluated. Finally, based on the genuine interest in using methods in different approaches to determine the optimum depth and the willingness of mining companies to use simultaneous and, or non-simultaneous mining methods, the conclusion was made.

Keywords:

Mining/metals industries , transition problem , combined simultaneous and non-simultaneous mining , combined mining methods