Open-Pit Mine Production Scheduling and Crusher Location-Relocation Plan under Semi-Mobile IPCC Systems

  • Author / Creator
    Liu, Dingbang
  • In most open-pit mines, material haulage costs can comprise over 50% of the total mining costs. This portion can even increase as the future mining conditions will become more challenging. Although the conventional truck-and-shovel system is adopted by over 95% of existing surface mines, in-pit crushing and conveying (IPCC) systems receive more attention to the modern mining industry due to their lower operating costs and carbon footprint than conventional truck-and-shovel systems. However, the IPCC system’s implementation can introduce substantial upfront investment and reduce mining flexibility; thus, careful mine planning and design are required before the systems' application.

    This study considers a situation that the conveyor is fixed in one pit side throughout the mine life, and it can be extended to deeper levels when the mining operation goes deeper. This configuration introduces additional mining direction requirements: mining starts from the conveyor side. It then expands to the other side of the level, and the mining activities below the conveyor line should be avoided. A set of candidate high angle conveyor layouts is generated along the final pit wall, and the situation for a conventional low-angle conveyor with ramp slots is also considered. Each conveyor scheme is considered a scenario for later calculation.

    The study aims to develop, implement, and verify a theoretical optimization framework to maximize the economic return measured by NPV while considering the total transportation costs under the application of semi-mobile IPCC systems. In this sense, three mathematical models are proposed to solve the problem from different perspectives. The first model is a two-step linear programming (LP) model for the conventional conveyor installed in the ramp slot. Its first step is a MILP formulation that aims to maximize the NPV; the generated scheduling results are fed to the second step, a facility location problem, to minimize the total transportation costs. The second model is a two-step model similar to the first one in which instead of the conventional conveyor and ramp slot, a high angle conveyor (HAC) is considered. The third model is a binary-integer linear programming (BILP) formulation for the HAC case, which can make the production scheduling and crusher location-relocation decisions simultaneously. All the presented mathematical models are run at a cluster level to reduce the computation time. A hierarchical clustering approach is applied to aggregate blocks into larger mining units, and their precedence relationships are determined.

    The main scientific contributions of this research on the body of knowledge are: (i) introducing a new production scheduling optimization strategy under semi-mobile IPCC systems by incorporating the mining direction requirements from the conveyor's perspective, (ii) developing a conveyor location optimization framework by generating various conveyor lines along the final pit wall and comparing the NPV under each location scenario, (iii) proposing mathematical models for making the production scheduling and crusher location-relocation decision to maximize the NPV while considering the transportation costs, with respect to operational and technical constraints.

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.