The percentage of extraction of coal from a pillar of 30m x 30 m center to center with roadways 4m wide is
?
1) 30
2) 28
3) 22
4) 25
Q2)
While working seams steeper than 1 in 4 except the haulage dip the cross connections between the levels
should be?
1) on mild gradient
2) provided with steps
3) straight aligned
4) staggered
Q3)
Overriding of pillars and stooks and premature collapse in the depillaring area is due to presence of?
1) Weak
strata
2) Water bearing strata
3) Strong thick massive sandstone
4) strong coal
Q4)
The limiting gradient for longwall method is?
1) 0 to 20 deg
2) 10 to 30 deg
3) 20 to 40 deg
4) 30 to 40 deg
Q5)
The first indication of roof weighting for regular fracturing roof in goaf is?
1) Prop when tapped with stick
produce dull and dummy sound
2) lid over the prop bends
3) rumbling sound in goaf
4) penetration of prop into floor
Q6)
In longwall advancing the gate roads extend slightly beyond the face and the extended portion of the gate is
called?
1) Buttok
2) Tail gate
3) Stable
4) Packwall
Q7)
The walls by which the roof over the goaf is partially or completely supported are
called?
1) Stalls
2) Ribs
3) Packwalls
4) None
Q8)
In longwall advancing stables are usually ... ahead of the face?
1) 6 - 8
2) 8 - 10
3) 4 - 6
4) 10 - 12
Q9)
A face is along the strike is preferable for stowing in seams dipping more than ?
10 1 in 10
2) 1 in 8
3) 1 in 6
4) 1 in 5
Q10)
Where sand stowing is adopted for stowing the goaf the maximum distance between the packed goaf edge
adn the face is restricted generally....m for proper roof control?
