A Critical Review of the Inputs to Long Range Mine Planning of Open Pit Porphyry Type Copper Deposits

Abstract

Long term planning is the process used by a mining organization to develop a strategic business plan. The plan describes how the ore is going to be extracted over the mine life. As such, it is routinely updated in order to declare annual reserves, evaluate options and react to changes in the initial assumptions. Inputs into this planning process are the parameters that drive profitability.

The purpose of this research is to understand and document the open pit long range planning process in current use by mining operations, isolate the input parameters that feed into this process, and conduct a critical review of these parameters in an effort to develop a more robust plan.

The thesis also searches for answers to the following questions: Can the copper metal price be correlated to a factor (or a set of factors)? Can the price be predicted? How useful is the work of O’Hara and Taylor in predicting the mine life and milling rate at the scoping study stage? How can the pit by pit graph be used to better guide the selection of the ultimate pit? Is there a realized benefit from operating at an elevated cutoff grade strategy with low grade copper porphyry deposits?

The research concludes with a proposal (not common in the industry) for the selection of the metal price as an input into the mine planning process. This approach, if implemented, can give a corporation a dominant position in the future. The research also presents a modified approach for the selection of the ultimate pit. Furthermore, the use of Taylor’s rule in predicting the mine life was tested and verified on an open pit copper porphyry deposit and the benefits of operating at an elevated cutoff grade strategy was demonstrated for the deposit.