Ore reserve valuation of mined-out areas and remnants at East Rand Proprietary Mines (ERPM)

ERPM was formed in 1893 and as a result of its age, a large volume of data exists in a paper-based format and it was decided to electronically capture data in one of two critical mining areas-namely at Far East Vertical (FEV) Shaft Area (Lower Areas) and Hercules Shaft Area (Upper Areas). The life of mine is dependent on tonnage and grade from these areas. Geostatistical evaluation of the gold reserves has been applied on an ad hoc basis in the Hercules Shaft Area and on a continuous basis in the FEV area. This is the first evaluation using geostatistics that was performed on the Upper Areas. This paper is based on the premise that regardless of cut-off grades, geostatistical estimation (kriging) estimates and locates reserves better than traditional, methods e.g. polygonal method, inverse squared distance method and it endeavours to estimate and locate the high grade reserves in the Main Reef Leader of Upper Areas.