Seams at shall depths, which are activity gassy liable spontanious heating, with bad roof are prefarably extracted by
A. Quarrying
B. Long wall
C. Bord and Pillar
D. Room and Pillar
Answer: Option A
A. Quarrying
B. Long wall
C. Bord and Pillar
D. Room and Pillar
Answer: Option A
Which test determines the sensitivity of explosive to shock and impact.
A. Rifle bullet test
B. Gap test
C. Ageing test
D. Water resistance test
The mining method which does not distroy the land for agriculture and residential purposes.
A. Striping
B. Open cast
C. Placer
D. Long wall
The output capacity of a drag line with 23 to 30m3 is million cu.m per year is
A. 0.25 to 0.75
B. 3 to 4.5
C. 1.5 to 1.7
D. None
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