Finding a needle in a haystack
Mathematical optimisation is a powerful technique which can search many thousands of potential solutions to tough mining, metals and commodity value-chain optimisation problems that start from run-of-mine (ROM) material and incorporate ROM reserving, logistics, inventory management, processing decisions and feed-grade control, while satisfying many hundreds or thousands of constraints. In the mining space, mathematically generated solutions to these problems must also satisfy different time-horizon objectives, from day of operations to budget forecasts to life-of-mine considerations. The complexity of finding feasible and optimised solutions to these problems is analogous to finding a needle in a haystack.
There are a variety of techniques that can be employed to reduce the size of the space of possible solutions that needs to be searched, allowing mathematical optimisation to find solutions to such problems. But even with such techniques, generated solutions often appear unacceptable or strange to the planners and schedulers who might make use of them, despite being “optimised”. This is perfectly understandable, because mathematical optimisation techniques suffer from the limitation of not capturing the nuanced insight of human decision makers, so while appearing optimal these solutions are limited in their practical application. This is not just an issue of the mathematical model not capturing sufficient detail, but relates to the significant experience and knowledge human decision makers bring to a scheduling or planning solution, which cannot be captured by any model.