Hi Simon.
I am surprised that you think that there should be more ‘traditional ‘ mines rather than quarries or open pit mines!
In my opinion the only thing that prevents open pit mines in the U,K. Is NImbyism., Way back in the late 1960”s I can remember the late Ivor Brown insisting that the only future for mining in the U.K., was open pit methods.
He told me at that time an overburden of around 200 -250 ft could easily be taken out and unlike deep mining all the mineral can be extracted. Since leaving it in the roof was a complete waste, and also, opencasting was a lot safer!