The data set includes gravel pits. You can filter them out by selecting "Underground" for "Type".

Wouldn't that also filter out every open cut surface mine that strips overburden and directly extracts near surface coal, copper deposits, iron ore, etc.

Not every mine is a "classic" underground mine with tunnels, etc.

See (for example) the W.Australian SuperPit gold mine which consolidated every shaft mine in a particular region into a single open pit that goes deeper than any pre existing underground mine in that area.