The diameter of holes in mm commonly used for ring drilling by drifters in sublevel stoping is between
A. 25 and 32
B. 33 and 44
C. 45 and 64
D. 65 and 100
Answer: Option D
Related Questions on Introduction to Mining Engineering
A. Normal distribution
B. Skewed distribution
C. Lognormal distribution
D. Poisson distribution
A. 3 level heading district
B. 4 level heading district
C. 5 level heading district
D. 6 level heading district
It is very difficult to control shaley roof if coal is not left with the shale why?
A. It is weak in nature
B. It has weathering effect
C. It has great affinity to absorb moisture and get departed from immediate roof
D. It reacts with coaly surface
Join The Discussion