An investigation into the impact of mine closure and its associated cost on life of mine planning and resource recovery

Best practise environmental and social processes for mine closure at the time of decommissioning are well documented; however mine closure is often not given the recognition that it warrants during early mine planning phases. While it is recognised that mine closure and its associated costs need to be fully incorporated into the life of mine planning process, it is often not to the extent that it should be. This paper seeks to quantify the value that may be lost if closure planning is not adequately considered in life of mine planning and the difference in the mine plan between scenarios that adequately consider closure costs and those that do not. To demonstrate this, a case study is introduced for the purpose of investigating the effect of mine closure on various aspects of the mine design of a two dimensional copper deposit. Results indicate that mining operations may benefit from an altered mine plan whereby mine life is extended due to the time value of money aspect associated with closure. In addition to increasing the Net Present Value (NPV), the other significant finding is that this may also significantly improve resource recovery for minimal additional environmental disruption. It is demonstrated that mine closure needs to be incorporated as part of the optimal mine planning process from the very outset. It is also suggested that orebody characteristics such as size, shape, grade and dip are key variables in the closure cost/mine plan relationship. Mine closure and its associated costs need to be incorporated into the mine planning process to thus play a significant role in determining the ultimate pit limit, pushback design, production schedule, mine life, resource recovery and ultimately the profitability and NPV of an operation.