Comparison of methods to define the final pit-a case study

Abstract

Elaborating a proper mine-planning is a crucial stage to define the success of a mining project. In the long-term it is desired to define the final pit and the mine sequencing, and this is the objective of the present paper, in which different methods were compared to get to the best viable economic result. Out of a database from a known copper deposit, two main methods were used to describe the behaviour of the mineral grade. The methods used were the Geostatistical model, using Ordinary Kriging, and the Inverse Distance Squared (IDS). Each one of them defined three pits using, respectively, Floating Cones algorithm, Lerchs-Grossmann (LG) algorithm and Direct Block Scheduling (DBS). The tests and their analysis showed that there are great variations on the results provided from each methodology. For IDS methodology, the economic difference between Floating Cone and the LG algorithm is about 62%, while the Kriging method resulted on a difference of 50%. In both cases, LG algorithm returned higher results. The comparison between scheduling methods shows that for IDS, DBS returned an economic result 17% higher than the Best Case and 23% for the Worst Case. Considering the Kriging method, the difference is about 16% higher for DBS in comparison to the Best Case and 22% for the Worst Case. All the results were obtained using specific software for each case.