Upto what gradient the bord and pillar mining adopted without special arrangements.
A. 1 in 4
B. 1 in 3
C. 1 in 5
D. 1 in 6
Answer: Option A
A. 1 in 4
B. 1 in 3
C. 1 in 5
D. 1 in 6
Answer: Option A
The required water for 1 ton of sand in hydraulic sand stowing is . . . . . . . .
A. 800 l
B. 600 l
C. 1100 l
D. 1200 l
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