Coal Mining - Study Mode

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[#461] In extraction of coal pillars by caving, what should be the maximum area of roof exposure at any working place at any time.

(A) 60 m 2

(B) 90 m 2

(C) 150 m 2

(D) 180 m 2

Correct Answer

(A) 60 m 2

[#462] Consider that pillar size is 30 m centre to centre and gallaries are 4 m wide. Find the percentage of extraction.

(A) 20%

(B) 26%

(C) 25%

(D) 30%

Correct Answer

(C) 25%

[#463] The input of water in the mixing cone is measured or calculated by an instrument . . . . . . . .

(A) Lea recorder

(B) Flow meter

(C) V notch

(D) Kent velocity meter

Correct Answer

(C) V notch

[#464] The device used for collect the core

(A) Sludger

(B) Boiler

(C) Sailer

(D) Barrel

Correct Answer

(D) Barrel

[#465] The pillars formed during development are split into small portions called . . . . . . . .

(A) Judd

(B) Stooks

(C) Slices

(D) Split

Correct Answer

(B) Stooks