You find the rich ice and asteriod mining drills as encrypted schematics in alien loot containers, that you then decrypt, (hopefully to the drills, but other techs as well), and unlock at a UCH research vessel. you may also be able to buy them from the uch research ships(i know you can buy some schematics, not sure if the drills are one of them though. never had to buy it.)

i've never used them myself. but you are supposed to be able to hit "p" and read the description of the drill for the exact settings to use for targeting so they fire on the asteroids(and not other things) when close enough. Then you head to locations with "rich" asteroids.

This is a video of Spanj the youtuber using them. Just the first part of the video.

https://www.youtube.com/watch?v=cVX-1rjtJ1s

he gets some of his information wrong apparently (like the targeting it seems), but it might help.

hope that answers your questions.

Sorry for the thread necro.
Are ice mining drills working for you guys? Mine don't work in singleplayer for some reason. Asking around before I make an official report.
Thanks.