Risk reduction of Grade Uncertainty in production scheduling of vein reserves (case study: Taknar copper mines)

Implementation the appropriate approaches to reducing the risk of uncertainties in Mine production planning process, maximizes net present value of extraction plan with high degree of confidence. In Maximum upstream potential/Minimum downside risk approach, the key economic factors in final plan, should be realized with any grade distribution of reserve. With reduction the risk of project evaluation factors as downstream, the upstream potential such as reserve tonnage must be realized at the same time. For implementation of this approach with some changes, in this study, 10 different grade distribution model of the copper vein reserve were simulated with a Gaussian simulation tool in Datamine software. At next step, after implementation of technical and economic parameters, the construction of nested pits for each simulated model as extraction plans and optimization performed with the Lerch-Grossman algorithm in Whittle software. Each plan were integrated into other designs obtained from simulated models. Then, the key parameter of each plan were calculated and some plans were eliminated. The calculation of upside potential and downside risks in remaining plans performed based on supplying of 95 thousand tons feed with an 80% probability of realization and the ability to return investment of 31 billion Rial that spent on the development of the second phase of the processing plant. Finally the high priority plan was selected. The mineable reserve in selected plan was estimated about 71000 tons with average grade of 0.25% copper, which is much lower compared to the 375000 tons that estimated in the previous studies.