Question

why did miners die in mines every year

Answer 1

miners work without mask
no security provision available for them

Answer 2

hey mate here is your answer

miners die in mines because of the work they do. when they enter into tunnels there are so many problems they face due to them they die some of the reasons are-
when they enter tunnel if the ground water overflows they may die.
the tunnels may fall on them .
there may be no oxygen for them to breath .

and in case of open cast mining if the bomb blasts when the person is there then he may die .

hope this helps you