Coal Mining - Study Mode

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[#321] Vertical shaft does not extend upto the surface called

(A) Staple pit

(B) Blind pit

(C) Long head

(D) All of these

Correct Answer

(A) Staple pit

[#322] The hydraulic sand stowing the goaf is adopted and the face is along the strike it should be slightly oriented at to provide drainage of water.

(A) 1 in 200

(B) 1 in 150

(C) 1 in 125

(D) 1 in 100

Correct Answer

(D) 1 in 100

[#323] During extraction of coal the minimum thickness of rib left against the goaf is

(A) 4 m

(B) 3 m

(C) 2 m

(D) 1 m

Correct Answer

(D) 1 m

[#324] The value of threshold convergence in longwall mining is mm/m.

(A) 30

(B) 40

(C) 50

(D) 60

Correct Answer

(B) 40

[#325] With a good sand stone roof the area explored may not be more than . . . . . . . . m 2 at one stook extraction.

(A) 20

(B) 30

(C) 50

(D) 40

Correct Answer

(D) 40