Estimating iron ore grade on the fly as recently blasted ore beds are dumped through a load out into train carriages for transport to ocean side processing (further crushing, screening, fine grading and blending) and loading onto shipping.
It's an 800 million tonne per year operation in W.Australia (somewhat larger than the US ~ 48 million tonne iron ore mining figures (IIRC)).
The alternatives are to find something else that can be "shone" like a flashlight through raw iron ore, and | or for the world to consume less steel.