Strategic mine method transformation to enhance marginal gold deposits and extend mine life

¹ Mining Engineering Department, Institut Teknologi Nasional Yogyakarta, Yogyakarta, Indonesia
² Mining Engineering Department, Universitas Pembangunan Nasional “Veteran” Yogyakarta, Yogyakarta, Indonesia
³ PT Studio Mineral Batubara, Yogyakarta, Indonesia

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The economic viability of marginal gold reserves remains a major challenge in the final stages of mining operations, particularly when constrained by underground mining methods. This study investigates a strategic transition from underground to open-pit mining to enhance the economic potential of marginal gold deposits and extend the overall life of mine. Focusing on a gold mine approaching depletion, the research evaluates the technical, economic, and operational implications of converting the mining method to access previously uneconomic ore zones. A comparative analysis was carried out between underground and open-pit scenarios using parameters such as stripping ratio, recovery factor, cut-off grade, and Net Present Value (NPV). A sensitivity analysis was also conducted to assess the influence of gold price, mining cost, and ore grade on project feasibility and risk. The results demonstrate that transitioning to open-pit mining significantly increases recoverable reserves by reclassifying marginal zones as economically viable, leading to improved project NPV and extended life of mine. In addition to economic benefits, the transformation supports operational continuity and improved resource utilization. Nevertheless, geotechnical stability, environmental management, and regulatory compliance remain critical aspects to be addressed in implementing such a transition.