What is the most dangerous type of mining

What the author of it is, date of publication, what state it came from,the publisher, and the sorce title



  1. 0 Votes

    You might try something called “retreat mining”, which is where they hollow out a huge area on the floor, only supported by a few pillars. Then they pull the pillars out. Guess what happens?


Please signup or login to answer this question.

Sorry,At this time user registration is disabled. We will open registration soon!