Conventionally, engineers will impose stope sequencing rules in order to ensure the stability of excavations as mining progresses. Typical rules include fixed direction, primary-secondary and chevron. Using a mine planning software suite, a mine layout is designed, and a set of stope-to-stope precedence links are created, enforcing the applicable rule. The mine planner produces a schedule that meets these and other constraints, in an effort to achieve a high net present value (NPV) for the operation. This time-consuming process limits the planner's ability to assess alternative mining strategies. Further, the process tends to over-constrain the mine schedule, since it is often the case that an alternative set of precedence constraints can enforce the same rule. By over-constraining the schedule, and by not assessing alternative strategies, significant value may be lost. The GeoSequencing Module is software that facilitates the assessment of stope sequencing strategies, through integration with the Schedule Optimization Tool (SOT). The GeoSequencing Module rapidly generates multiple alternative sets of stope-to-stope precedence links that enforce stope sequencing rules selected by the user. Each set of precedence links is referred to as a geosequencing scenario. For each geosequencing scenario, SOT optimises the life-of-mine schedule, allowing the planner to identify the scenario that supports the highest value for the mining operation. Furthermore, the software has been integrated with a boundary element solver, facilitating assessment of the geotechnical stability of the optimised schedules. A case study for an underground mine has been conducted to validate this methodology. The study demonstrates that multiple mining strategies can be conveniently assessed to determine which scenario yields the most desirable outcome for the mining operation in terms of both geotechnical stability and financial assessment.

The identification of high-value, practical mine plans is a complex and challenging process. Mineral prices are a crucial factor to the value of a project and, due to the inherent volatility of the commodities market, also the most uncertain. Despite this reality, conventional planning processes don't sufficiently account for the financial uncertainty associated with mining assets. As a consequence, life-of-mine schedules must often be extensively revisited as the fiscal climate changes. The inherent financial uncertainty of mining projects presents a substantial risk to stakeholders and without proper mitigation can easily reduce the perceived and real value of a mining asset. The risks associated with uncertainty can be mitigated through the creation of robust mine schedules. In this paper, two distinct approaches to creating robust, optimised long-term underground mine schedules will be presented. The Genetic Optimizer for Stochastic Problems (GOSP) method incorporates price distributions, rather than fixed projections, into the optimisation process. The Horizon method incorporates the concept of 'management flexibility' into the process of schedule optimisation. As will be demonstrated by a case study, these methods, when integrated with the Schedule Optimization Tool (SOT), produce robust, high net present value schedules for underground mining operations.