Mutual constraints and interdependencies make scheduling in underground mines difficult, making many mathematical optimization methods inefficient. The article discusses an approach to scheduling underground mining operations based on maintaining work-in-progress buffers and iterative adjustment of the plan using a simulation model. The key advantage of the proposed approach is the ability to consider the probabilistic factors inherent in the real world.(more…)
Copper production is a great example of facility with multiple constraints and interdependencies that requires simulation to support decisions. The conventional process-oriented approach implies using multiple local optima rules to simulate manufacturing operations. For example, every time the model needs to decide where to transport a ladle with hot metal, it looks for the closest available converter that can take the metal. Using such rules to model the copper plant leads to deadlocks such as having too much white metal and no available converters to process it.
To address this problem, we developed a scheduler as a separate module that generates a well-balanced schedule of the main production process using an iterative algorithm with stepwise constraints relaxation. The schedule is passed to the model that simulates plant operations trying to adhere to the schedule. The simulation considers cranes logistics, limited number of ladles, fluctuations of processing cycles and multiple other aspects. If the model starts falling behind the schedule, it requests the scheduler to generate a new schedule starting from the current state of the plant. This interaction between the scheduler and simulation model produces a realistic schedule that accounts for most constraints and interdependencies of copper production process.
The operation of offshore drilling platforms requires a lot of logistics: supply of platforms by platform supply vessels (PSVs), backward transportation of waste in containers and transportation of oil by tankers to export ports. The severe weather conditions of the Arctic Ocean increase the number of possible disruptions that influence the logistic system. The operation of PSVs and tankers has multiple constraints and interactions. An agent-based simulation has been developed in AnyLogic to support the strategic planning of logistics by year 2042. The presentation discusses the use of the model to determine the required number of vessels and compare different options of crude oil outbound logistic network design.
Planning of potash mining operations requires consideration of many interacting machines, overlapping maintenance activities, layout of mine field as well as capacity of ore bunkers and conveyors. Integrated low-level simulation with user-friendly interface was developed to support monthly operations planning in Europe’s largest potash producer. In this presentation, an example of using simulation in operations planning is given and created decision support tool is demonstrated. Main challenges that were met and overcome during development of simulation-based decision support tool are also discussed.