Profit-Driven to Purpose-Driven Mining: Integrating Carbon Penalties and Sustainability Metrics for Optimizing Transition Depth from Open-Pit to Underground Mining
摘要
The optimal transition depth between open-pit and underground mining is a decision that is vital and balancing in terms of technical viability, economic gain and sustainability goals. Conventional approaches, such as the Maximum Allowable Stripping Ratio (MASR), pay more attention to the geometric and economic parameters but do not take into consideration the environmental and social costs. In this research, the author proposes an approach that would help to integrate sustainability into the transition planning by using Sustainability Adjusted Net Present Value (SNPV) combining the carbon penalties and social issues with the traditional economic indicators. Hypothetical 2D ore deposit in a tabular form is modeled to compare the transition depths of the deposit as determined using the MASR and the SNPV methods. The analysis performed using MASR provides an estimated transition depth of 285 m and a Net Present Value (NPV) of ₹5074.21 million. A carbon penalty of ₹4000 per tonne of CO2 emission and sustainability adjustments cause a transition depth to be 225 m with a lower SNPV of ₹3540.78 million. Sensitivity analysis also indicates that an increase in CO2 emission by 20 percent caused a 7.57 percent reduction in SNPV, and open-pit mining was more vulnerable to such changes than underground mining. The study results also show that integration of the environmental and social cost can change the decision on transition depth substantially and encourage the shift toward underground mining earlier and the adoption of the operational strategies that are consistent with the Environmental, social, and governance (ESG) principles. The framework suggested in this paper will give a realistic solution to sustainable mine planning, which will help in not only profitability, but also environmental accountability in the mining sector.