Global Optimization with no stepwise process!
It’s a great question!
What we recommend in this case is building a graph like this:
In the X axis, you place the indicator “Period to remove the infrastructure.
In the Y axis, you place the NPV or any other important indicator of your choice (productions, grades, etc.).
Each point in this graph will be the result of one Run of MiningMath.
1) You can build a new Decision Tree here:
2) Setup a Base Case scenario, without considering this constraint. This is infeasible, but tends to give you an NPV upper bound to your project.
3) Copy this Base Case scenario and add your constraint as loose as possible. In your specific case, you need to use the Period Intervals and the concept of Restrict Mining, as depicted below and better explained here.
For example, you could add this Restrict Mining Surface until year 1, and leave from 2 to <end> free. Meaning, you can access this area from year 2 on.
4) Repeat this process to create new scenarios that tighten your constraint slowly. For example, changing the interval from 1-1 to 1-2, 1-3, 1-4, 1-5, 1-7, 1-10… .
5) Dependeding on your computer RAM and processing power, you can open multiple instances of MiningMath and run scenarios in parallel. Caution not to overload your computer so that Windows start to shut down the processes.
6) If you need even more efficiency in a less precise evaluation, consider these tips: Timeframes and/or Time limit.
7) Each run will provide one dot in your graph, which could be placed on your final reports, facilitating the decision making process.
8) Note that this procedure could also be used to all the ohter constraints of your project, to better understand the impact of each one. 😍
How could we best assist you in this process?