The application of geophysics to iron ore mining in the Hamersley Basin, Western Australia

Abstract

Hamersley Iron Pty. Limited operates five iron ore mines and has a number of advanced evaluation projects in the Hamersley Basin, Western Australia. These deposits range in style from bedded iron in banded iron formation host, to detrital iron accumulations. Numerous problems are encountered during mining in these varied geological environments. These include pods of high manganese concentration, self-igniting black shales, definition of detrital iron accumulations, fault-exploiting dolerite dykes, and lithology determination, amongst others. Each of these problems requires an unique solution. For example, natural gamma ray logging is used to determine stratigraphic level of intersected lithologies. Together with other parameters, this method is now being extended to identify actual lithologies using artificial intelligence technology. Ground penetrating radar and radio imaging methods are employed to outline ore geometries and assist in assessing ore quality. More classic methods, such as high resolution ground magnetometry and resistivity are used to define dykes, map structures and support ore block modelling. Thus, geophysics is now playing an integral role in mine site planning. As a result, production costs should decline, and product quality should improve through better definition of ore/waste geometry.