Core recovery and quality: important factors in mineral resource estimation / Извлечение и качество керна: важные факторы при оценке минеральных ресурсов

The estimation of mineral resources is critical to all mining operations irrespective of size or commodity.1,12 The risks associated with mining are varied and complex, where the dominant source of risk is the orebody itself. Reverse circulation (RC) and diamond core drilling methods are used extensively for the collection of samples from depth. These data generally form the critical base for both geological and grade modelling, leading to the mineral resource estimate and ultimately the ore reserve estimate. It is well known that diamond drilling generally provides a higher quality sample, better suited to resource estimation than RC drilling, especially for gold deposits.1,6,7,11 RC methods are sometimes applicable to the resource evaluation of alluvial/unconsolidated deposits, though can be highly problematic when applied to gold deposits.7 Current methods of resource classification relate to the geological, economic and technical confidence in the resource.14–16 Geological confidence is largely related to the level of drilling and sampling in the orebody, to the geologist’s perceived level of confidence in his or her work, and to the continuity of the mineralisation. This contribution reviews the geological and technical factors that affect core recovery, how core recovery is measured, the impact of poor recovery on the resource estimate, and how to deal with lost core during estimation <...>