Errors of estimation due to mineralization and sampling density in massive copper deposits

Abstract

ABSTRACT This study is aimed to determine the effects of spatial variation of the grade, and sampling density, on the errors of estimations of the geological and recoverable reserve for typical massive copper deposits. A spectrum of copper deposits which have log-normal distributions was numerically modelled on a rectangular grid using the simulation method of turning bands. Spherical variograms with six different random to structured variance ratios were used. The mean block grades were estimated for four different sampling densities by employing the kriging method. The two-dimensional dynamic programming algorithm was utilized for determining the ultimate pit limits. The estimation errors were calculated by deducing the actual values from the estimated values. The magnitude and patterns of errors due to a broad spectrum of sampling density and nugget effect values have thus been determined. It has been found that the percent estimation error for the recoverable net value is much higher than the percent ...