Quantification of logistics performance in ultra deep mining - a South Deep Gold Mine case study

Abstract

Ultra-deep mining internationally is constrained by various factors that are directly proportional to the operating depth below surface. One of these factors is the logistics related to personnel, material, and ore, specifically the function of transportation. This is primarily due to excessive vertical depths below surface and horizontal travelling distances to workplaces. A direct impact on production is subsequently caused by the inefficient utilisation of personnel to conduct core production activities. This inefficiency can be seen when comparing actual times spent by employees conducting core production activities, total time spent travelling, and overall shift duration. It is demonstrated throughout this research that, as mines become deeper, more time is spent on travelling and less on core production, as a result of increased travelling distances and logistical function ineffectiveness. In terms of conventional Lean Six Sigma theory, the transportation function in a production mine could be considered a non-value-adding process or even waste (muda). In order to maximise time for primary production activities (maximise face time), waste must be minimised or waste processes optimised. This can be done using the set sequence methodology of the Lean Six Sigma DMAIC (Define, Measure, Analyse, Improve, and Control) Model, whereby the personnel logistics performance of any mine can, first, be quantified and thereafter optimised. South Deep Gold Mine is an ultra-deep mine; it is currently the seventh deepest in the world and is notoriously constrained by logistics challenges. This mine was therefore used as a known case study to quantify and optimise personnel logistics performance using conventional Lean Six Sigma theory, although this theory is not conventionally applied in ultra-deep mines. Results of this research indicate that, through the correct implementation of Lean Six Sigma theory, personnel logistics performance can be quantified accurately and thereafter greatly improved. The face time efficiency factor developed for the purposes of this research and used as the primary metric for the quantification of personnel logistics performance is deemed a success, and could be applied to any underground mine to determine the efficiency of the transportation of persons to and from workplaces. The research, in the opinion of the researcher and subject matter experts in the ultra-deep mining environment, especially at South Deep Gold Mine, adds value to the international ultra-deep mining network, especially with regard to optimising time spent on core production activities (face time efficiency factor) and benchmarking/comparing ultra-deep mines on personnel logistics performance.