Risk mitigation through the use of geophysics

Abstract

There are three principal sources of risk in mining and exploration: the external market, process and mining risk and geological risk. Only the external risk is truly beyond the control of the owner / operator. Underlying all other risk is the quality of the understanding of the geological risk that underpins mining and processing decisions. A number of case studies are discussed which highlight areas where Anglo and affiliated companies have employed geophysics to reduce the geological risk in exploration, delineation and production. Geological risk is intrinsically 3-dimensional in nature. Despite the fact that the parameters that describe a geological entity can generally be measured with some precision, e.g. density, grade, chemical composition and hardness, lack of access in the third dimension (depth) combined with cost, means that we invariably deal with incomplete data sets. Yet it is precisely the geological model that informs the type and size of mine and processing options. The chances are that the resulting mine / process options will be sub-optimal and in the worst cases completely wrong. Acquiring the necessary information costs money. Not having the information inculcates risk. There must be an optimum position where the overall cost of the information and the reduced risk is at a minimum. Traditional methods of exploration / delineation no longer suffice. A judicious mixture of traditional and geophysical methods offers an opportunity to gain an adequate understanding of the critical geological parameters and thereby make better decisions on mine / process design.