Development of a best-practice mineral resource classification system for the De Beers group of companies

摘要

The De Beers Group of Companies has operating diamond mines and exploration projects in numerous countries including South Africa, Namibia, Botswana, and Canada. Diamond deposits are often geologically complex and typically characterized by significant variability in terms of grade and other variables. In addition, diamond revenue also needs to be estimated. These issues make evaluation sampling difficult and accurate Mineral Resource estimation problematic. De Beers identified the need for sound Mineral Resource classification that highlighted areas of uncertainty in the Mineral Resource. As a result De Beers has invested considerable time in developing a best-practice Mineral Resource Classification System (MRCS). In 2004 De Beers developed a prototype that identified the five key Mineral Resource criteria of geology, grade, volume, revenue, and density. A set of key questions and associated answers was developed for each criterion and a scoring system introduced. The MRCS prototype was tested on a wide range of De Beers diamond deposits. Critically, this extensive database of deposits allowed the questions, scoring, and priorities to be adjusted until representative and consistent classifications were produced. The MRCS has evolved through time and, more recently, significant changes have been made that include the ability to take cognisance of new data obtained during mining and production performance. The process involves the project geologist completing the five scorecards, which are reviewed internally prior to an independent review and final ratification by a Competent Person (CP). De Beers is of the opinion that the system is leading practice and provides a repeatable and constant depiction of the confidence in the Company's mineral resources.