Estimation of Gold Resources from Exploration Drilling using Conditional Simulation - A Case Study

Estimation of gold resources from exploration drilling has passed through various phases and methods at the AngloGold Ashanti, Iduapriem Mine Limited, Tarkwa in Ghana. From the use of Inverse Distance Weighting (IDW) to the use of Ordinary Kriging (OK) and currently the use of Uniform Conditioning (UC). This is all with a view of improving the estimations before the grade control drilling is undertaken for mine planning and subsequent mining. This paper compares the estimates obtained from exploration drilling using conditional simulation with the results from ordinary kriging and actual production figures on a block by block basis for areas that have already been mined in the deposit. The results show that estimates using conditional simulation and ordinary kriging are similar; and, both appear to underestimate the resources.