Questions and answers for exam Preparation

MCQs

Total Questions : 2215 | Page 221 of 222 pages

Question 2201. Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed ?

Wet grinding in low viscous suspension
Wet grinding in high viscous suspension
Dry grinding of large particles (upto 1.25 cms)
Dry grinding of large particles in un-baffed mills

Discuss Question

Answer: Option D. -> Dry grinding of large particles in un-baffed mills
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2202. Use of baffles in agitators help in minimising the ______________ tendency?

Swirling
Vortexing
Both A. & B.
Neither A. nor B.

Discuss Question

Answer: Option C. -> Both A. & B.
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2203. Pick out the wrong statement?

Recycled coarse material to the grinder by a classifier is termed as circulating load
Wear and tear in wet crushing is more than that in dry crushing of materials
Size enlargement (opposite of size reduction) is not a mechanical operation
A ‘dust catcher’ is simply an enlargement in a pipeline which permits the solids to settle down due to reduction in velocity of the dust laden gas

Discuss Question

Answer: Option C. -> Size enlargement (opposite of size reduction) is not a mechanical operation
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2204. Pick out the wrong statement ?

Hammer crushers operate by impact action
Standard screens have circular opening
With increase in mesh number of screens, their diameter in microns decreases
200 mesh screen has 200 openings per linear cm

Discuss Question

Answer: Option D. -> 200 mesh screen has 200 openings per linear cm
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2205. Ore concentration by jigging is based on the difference in the ______________ of the particles?

Specific gravities
Wettability
Shape
None of these

Discuss Question

Answer: Option A. -> Specific gravities
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2206. Pick out the correct statement ?

Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products
The operating cost of shaking screen is more than that of a vibrating screen
Screen capacity does not depend upon the specific gravity of the minerals
Asphalt is best crushed using toothed roll crusher

Discuss Question

Answer: Option A. -> Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2207. Pick out the correct statement?

The capacity and the effectiveness of a screen are the same
The capacity and the effectiveness of screen are opposing factors
The screening surface of a ‘reel’ (a revolving screen used in flour mills) is made of silk bolting cloth supported by wire mesh
Both B. and C.

Discuss Question

Answer: Option D. -> Both B. and C.
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2208. Pick out the wrong statement pertaining to the roll crushers?

Maximum feed size determines the required roll diameter
For hard material’s crushing, the reduction ratio should not exceed 4
Both the rolls run necessarily at the same speed
Reduction ratio and differential roll speed affect production rate & energy consumed per unit of surface produced

Discuss Question

Answer: Option C. -> Both the rolls run necessarily at the same speed
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2209. Pick out the wrong statement?

Close circuit grinding is more economical than open circuit grinding
Cod oil, beef tallow or aluminium stearates are used as grinding aids in cement ‘industries’
The equipment used for the removal of traces of solids from a liquid is called a classifier
Size enlargement is a mechanical operation exemplified by medicinal tablet making

Discuss Question

Answer: Option C. -> The equipment used for the removal of traces of solids from a liquid is called a classifier
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 2210. Pick out the correct statement ?

Plastic chips are called non-cohesive solids
Kick’s crushing law is, P/m = K . ln (D̅ sa/D̅ sb)
Communition is a generic term for size enlargement operation
Energy required in kwh per ton of product, such that 80% of it passes through a 200 mesh screen, is called ‘Work index’

Discuss Question

Answer: Option B. -> Kick’s crushing law is, P/m = K . ln (D̅ sa/D̅ sb)
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!