Methods to optimise underground mine production

Abstract

The focus of this study was to investigate the current underground conventional mining systems used in the platinum mining industry and to design a mine production planning system to optimise the conventional operations - Anglo Platinum specific. The maximum steady state micro output levels of underground mines were determined from a mining and engineering perspective and the GAP, or output potential compared to the current output levels, was established. All the production facility's requirements with regard to services, equipment and infrastructure to achieve optimum production levels were calculated from first principles and a modelling tool for technical and mining optimisation evaluations was designed for use by the operations. Furthermore, an analysis of the main infrastructure or so-called "ongoing capital development" was done as a means to determine the maximum sustainable shaft capacities. With the main objective being to determine the existing production GAP and thus the requirements to fill this GAP, a picture of the current conditions, equipment capacities and output levels were determined. For this purpose, specific checklists were designed to capture all the relevant information. It was sub-divided in such a way that inputs could be made in a logical sequence to prevent backtracking exercises. The existing infrastructure and equipment were rated on a scale ranging from zero to ten with zero meaning non-existent and ten being brand new. The involvement of the site personnel throughout the entire process is a crucial part of the exercise as buy-in and ownership are probably the most important aspects of any implementation process. This buy-in was achieved through planning workshops and presentations where real examples from the audience where modelled. Members were allowed to change parameters and outcomes were debated. The systematic logical approach and the suite of practical outputs sold the system during every session held. Support came from all functions including mine design specialists and ore resource managers using different systems. The mining industry is the largest source of foreign income for South Africa and it is also the main source of employment with Anglo Platinum employing in the region of forty thousand employees1 and contractors. Reef deposits are not replaceable and it is in the interest of all stakeholders to extract every unit in the most efficient manner. Mines require vast amounts of capital and with risks like fluctuating metal prices, exchange rates, rising costs, labour unrest and geological uncertainties, it is important to have optimum planning and management systems in place. This project focused on how to optimise the output levels of current operations thus minimizing all of the mining-related risks in a direct or indirect manner. It is a simple means to leap closer to mining professionalism in first-world countries. The GAP varied between the different operations and ranged between overproduction and 60% below the optimum potential. On average it was 50% below optimum performance levels2. It has to be noted that these observations are based on half levels outputs and not on shaft capacities. In other words, where shafts are operating at design capacities, the same production can be obtained by manning half the amount of levels implicating cost savings instead of increased production. The current planning practices are thus not adequate to truly optimise the operations.