Abstract

MADOWE, A.. The mine planning process for an open-pit diamond mining operation - a case study on Letseng diamond mine in Lesotho. J. S. Afr. Inst. Min. Metall. [online]. 2013, vol.113, n.7, pp.547-554. ISSN 2411-9717.

This paper discusses the mine planning process for Letseng diamond mine in the Kingdom of Lesotho, in conjunction with the various software packages used during the process. The major pillars of the long-term mine planning process at Letseng are pit optimization followed by pit design and scheduling. Letseng uses Gemcom Whittle and GEMS for pit optimization and design and Runge XPAC for scheduling. The output of the mine planning process results in the generation of published mineral reserves and provides input into the Letseng overall business plan. The process of defining the key inputs for the entire mine planning process is discussed, which covers: ► Slope design as an input ► Diamond price inputs ► Operating and capital cost inputs ► Generation of pit shells ► Selection of an optimum pit shell and interim cutbacks using operational scenarios ► Sensitivity analysis on the selected optimum pit shell. ► Slope design criteria in the detailed design ► Split shell vs concentric pit design ► Practical mining widths to determine cutback design ► Pit design process in the GEMS software package. ► Development of scheduling scenarios in the XPAC software package ► Planning through mining production bottlenecks. ► Company-level NPV model ► Comparing scenarios and input of the different schedule scenarios into the company NPV model.

Keywords : pit optimisation; mine planning; pit shell; recovery; dilution; revenue factor; pit design; split shell; sensitivity analysis; scheduling; production bottleneck; NPV; discounted cashflow.

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