Boss: Bob, I need another mine plan for the iron ore complex.
Bob: No problem. That’s what I do, Boss.

Boss: This just came down from above. They want a bunch of scenarios run on different crushing rates. They also want scenarios on the timing of commencement of those satellite pits.
Bob: I thought I just…
Boss: Different this time. New parameters. Crushing to vary between 26 and 35mtpa on 1mtpa increments with specific costing for each. We also want to evaluate the satellite pits commencing on each of the years in the schedule for contribution to the blend.
Bob: So if I understand what you’re saying, Boss, that’s 10 possible crushing rates with further evaluation of the 3 satellite pits in each possible period over a 10 year mine plan?
Boss: You got it.

Bob: Ah, Boss, that’s 300 scenarios. Using our excel-based mine scheduling tool that will take me, hmm, let’s see, with an hour per scenario…about a month. Bear in mind, I’m a guru at this thing. A ninja. The best. Of course, that’s a month if I sleep. However, if I only sleep 4 hours per night I could get it done in about two weeks. You’ll have to feed me at my desk.

Boss: There has to be a better way. Well, Boss, there is. And it’s called Alternative Process Optimization.

What is Alternative Process Optimization?

In basic terms, Alternative Process Optimization is a technique that solves for the best possible ‘arrangement’ given simultaneous consideration of all other available ‘arrangements’. In mine scheduling, this best arrangement means finding an optimal schedule which goes beyond the problem of the simple block extraction sequence. It encompasses modelling alternative paths for downstream components, and uses all this to represent the spectrum of operating options.

What can it do for us?

We can employ Alternative Process Optimization in a number of ways to assist us in mine scheduling, from determining cut-off grades and material destination policies to choosing the best possible mill configuration from a range of choices. It can also provide a framework for our equipment selection.

How can it reduce our workload?

This technique can significantly reduce our planning workload as it effectively decomposes the traditional approach of scenario evaluation into a single optimization problem. For Bob’s classic example above, taking the traditional route would involve creating a large scenario matrix by hard-coding specific parameters, one permutation per scenario, to represent a solution for each possible option. It only takes a few parameter variations and a few scheduling periods before the matrix becomes enormous. It would take a major effort to individually solve and compare each scenario. If we use alternative process optimization, we will need to invest an incrementally larger set-up time in the beginning. However, this will be more than offset by the fact that we only have to run a single optimization to get the answer. And, as it employs a mathematical model to optimize our unique problem, we can be guaranteed there is no better solution.

How can we access this technology?

Alternative Process Optimization is embedded in Minemax Scheduler and has been successfully used to solve these types of problems for many years. The technique uses a split decision link framework to define alternatives for our real operating options. We can then map input information to these definitions called alternative processes. During optimization, this will provide logic for making optimal decisions regarding which blocks contribute to which alternative processes. Contact Minemax to learn more about alternative process optimization and how it can change your approach to scenario analysis.