Analyzing the effect of ore grade uncertainty in open pit mine planning; A case study of Rezvan iron mine, Iran

Due to uncertain nature of grade in ore deposits, considering uncertainty is inevitable in geological modelling of resources and mine planning. In other words, uncertainty in grade of mineralized materials, is one of the most significant parameters need attention in mine planning. In this paper, a comparative procedure utilizing Sequential Gaussian Simulation (SGS) and traditional Ordinary Kriging (OK) was applied in an iron ore mine, and the influence of ore grade uncertainty in mine planning was investigated. It was observed that grade distribution, resulted from the SGS is almost identical to that of the real exploration data as compared to the OK method. Also it is emphasized that uncertainties including ore grade of deposit would significantly affect the technical and financial aspects of plans. Comparison shows that the simulation-based ultimate pits exhibits less risk in deviating from quantity and quality targets than traditional approach based on a single orebody model obtained by OK method. Using SGS method, there was an increase in the value of net present value of mine plans.