Sample Optimization and Confidence Assessment of Marine Diamond Deposits using Cox Simulations

Conditional simulations are used to develop realistic and quantitative images of spatial variability for analysis. In particular, they are often used to evaluate the impact of uncertainty in applying economic optimization to a natural resource. Algorithms for conditional simulation of geological data and ore grades are well established. However, the majority are not applicable to placer diamond deposits which exhibit a discrete and patchy textural nature. This prompted the development of a new, enhanced suite of algorithms specifically designed for conditional simulations of diamond deposits. The Cox simulation algorithm is fast, incorporates complex mineralization structures, handles large sets of conditioning data and covers several different discrete distributions including those that are highly skewed. In addition, tests are available for model validation of both the distributional and spatial integrity. This enhanced conditional simulation tool is used, firstly, to determine the confidence limits of block estimates and secondly, to quantify and manage the risk of selective mining above an economic cut-off grade.