Document Type : Original Research Paper

Authors

• Javad Lotfi Godarzi ¹
• Ahmad Reza Sayadi ²
• Amin Mousavi ²
• Micah Nehring ³

¹ PhD Student at Tarbiat Modares University

² Tarbiat Modares University

³ Lecturer, School of mechanical and mining engineering, University of Queensland

Abstract

The production rate and cut-off grade are two critical variables in the design and planning of open-pit mines. Generally, the production rate depends on the reserve amount, which is influenced by the cut-off grade. Additionally, the cut-off grade is affected by the production cost, which is influenced by the production rate and product price. A conventional approach optimizes each variable individually, and neglects the trade-off between production rate and cut-off grade, leading to a sub-optimal solution. This work aimed to address the simultaneous optimization of the production rate and cut-off grade and provided a novel solution for this problem. In this context, a non-linear mathematical model was developed. The Particle Swarm Optimization (PSO) algorithm was used due to the model's non-linear nature and the continuous decision variables. Implementing the model for a typical copper mine showed that the suggested model resulted in a concurrent optimization of production rate and cut-off grade. The maximum NPV of 1.153 billion dollars occurred at a production rate of 15.66 Mt/y, and a cut-off grade of 0.64%. Additionally, a sensitivity analysis was conducted for key factors such as product price, discount rate, and maximum capital cost.

Keywords

• Cut-off Grade
• Production Rate
• Particle Swarm Optimization (PSO)
• Open-pit mining

Main Subjects

• Simulation & Optimization