One way to reduce waste and the environmental impact of open cast and underground mining might be to process the raw material on site, at the mine, and quickly return the waste back to where it was mined from.
So the footprint for an open cast mine would only correspond to the area actually being mined at that point in time; former areas having been covered in and replanted.
Underground mines would have a minimal footprint above ground as all mining and processing (extraction/refining) would take place underground in the mine. Only the extracted/refined product would emerge from the mine. There would be no old (collapsing tunnels) as they are filled in when no longer in use, and this would prevent subsidence caused by mining.
There are potential opportunities to do this via the use of innovative technologies, machines and robots. The benefits mean less environmental impact, no subsidence, and no transporting of waste materials. It’s also likely to offer an efficient and profitable enterprise.