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Mining Geologist, Steffen Robertson and Kirsten (UK) Ltd, Mining Consultants, Summit House, 9/10 Windsor Place, Cardiff CF1 3BX, UK
In 1965 Lerch & Grossman produced a paper describing a 3-D algorithm based on graph theory which could be specifically applied to the optimization of open-pit mine designs. At the time, most computers were incapable of performing the large quantities of iterative calculations required by the method. A 2-D algorithm was also described which, though effective on sections, lost its optimized quality when sections were combined. The 3-D algorithm therefore remained the preferred option.
In 1986 the Whittle 3-D open-pit optimization package was launched by Whittle Programming Ltd. This package utilized the Lerch-Grossman algorithm for the first time in a commercial software application. Since then the package has undergone a number of changes and improvements.
The purpose of an optimization package is to produce the most cost effective and most profitable open-pit design from a block model of an orebody. It must be capable of rapidly analysing alternatives accurately; it must be able to carry out sensitivity analyses of different components to assess financial risk; it must allow frequent updates to take into account changes in costs etc. and it must allow the production of interim designs. In today’s mining world, a hastily produced or non-rigorous design is financially unacceptable as the design determines the potential for profit or loss. To develop this further it is essential not just to make a profit but to maximize the return on investment.
This paper appraises the ability of the Whittle 3-D package to satisfy this objective.
