Mine roof bolting - GIF

[nova_robotics]

Rock anchors into a coal seam? Why is there no coal dust coming out when they're drilling?

[ductape]

Rock anchors into a coal seam? Why is there no coal dust coming out when they're drilling?

A very small amount of some kind of liquid appears to splash around. Doesn't seem to be near enough to catch all the dust expected from this operation, but who knows.
I have a few of these type of bolts used to hold up the roof of coal mines, and they are nowhere near as soft as the one showed here. Almost but not quite tool steel. They weld together good enough, but no fun to machine. Kind of like sucker rods from an oil well.