Global estimates of ore reserves in a beach sand deposit

Several techniques are available for determining the global estimates of ore reserves. However, among these techniques, only the geostatistical technique provides estimates with the associated estimation variances that allow the determination of meaningful confidence intervals, and, hence, risk-quantified reserve estimates. Such estimates should provide the basis of planning during all the phases of mining projects, including feasibility, mine planning and production scheduling. This paper outlines the geostatistical global estimation technique that is commonly applied to massive and thick sedimentary deposits. This is followed by a step-by-step application of the technique to a beach sand rutile deposit. Based on the data derived from 21 vertical drillholes drilled on a regular grid of 30 m by 30 m, the global estimates and the corresponding estimation variances were determined for the deposit under consideration. A comparison of the resulting estimates with the corresponding values obtained from the combination of kriged block estimates revealed that the two sets of estimates are almost identical, indicating the accuracy of the results.