Vertical Rate

The vertical rate of advance (VR) or sinking rate is also considered within the objective function on MiningMath, which means that it will be used to deliver the best result considering constraints hierarchy, even though it has a low priority. This parameter is defined as the vertical distance mined on each period, which depends on the pit depth and equipment available.

It is important to understand that this is also a 3-dimensional non-linear model, which means that it is a complex parameter within the optimization. The VR works as an upper bound to avoid operationally unfeasible solutions. Therefore, testing different values is a great strategy to identify opportunities that could bring the best mining sequence and NPV.

The Mining Width (MW) is an important parameter when defining the Vertical Rate. The MW and VR, together, define volumes of material for each mining period. A reduced MW might create additional challenges for the algorithm to comply with the VR. Therefore, it is important to play with different values, especially when VR is not being fully respected. Figure 1 illustrates a McLaughlin profile where the vertical rate of advance can be observed. Sub-vertical advances are also contemplated by this constraint.