chemical engineering mechanical operations Mcqs
401. Which of the following is not a non-metalliferous mineral ?
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A. Fluorspar

B. Quartz

C. Calcite

D. Cassiterite
402. Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them ?
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A. Jaw crusher, Ball mill, Fluid energy mill

B. Fluid energy mill, Ball mill, Jaw crusher

C. Fluid energy mill, Jaw crusher, Ball mill

D. Ball mill, Jaw crusher, Fluid energy mill

403. Trommels employ _____________ for screening of materials?
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A. Punched plate

B. None of these

C. Fibrous cloth

D. Woven wire screen

404. Which of the following is the softest material ?
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A. Calcite

B. Talc

C. Feldspar

D. Corundum

405. Pick out the wrong statement ?
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A. Cake resistance is independent of the pressure drop

B. Gyratory crusher is a coarse crusher

C. Crushing of explosive materials are done by employing dry-grinding

D. stant

E. For the compressible cake, voidage & the specific resistance of the cake can be assumed to be

406. In the cyclone separator used for separation of dust from dust laden gas, the gas ?
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A. Enters the cyclone from the top

B. Is admitted tangentially at high velocity

C. Develops a helical motion inside the chamber

D. Both B. and C.
407. The material is crushed in a gyratory crusher by the action of__________________?
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A. Cutting

B. Compression

C. Impact

D. Attrition

408. Fluid medium used in the classification technique of mineral beneficiation is_________________?
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A. Air

B. Neither A. nor B.

C. Water

D. Either A. or B.
409. Grindability of a material does not depend upon its_____________________?
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A. Size

B. Hardness

C. Elasticity

D. Toughness

410. _____________ are mixed using ribbon blenders ?
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A. Lumpy solids and low viscosity liquids

B. Thick pastes

C. High viscosity liquids

D. Dry powders
411. Which of the following represents the plot of filtrate volume versus time for constant pressure filtration ?
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A. Exponential curve

B. Hyperbola

C. Parabola

D. Straight line

412. Filter medium resistance is important during the ______________ of filtration?
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A. Early stages

B. Final stages

C. Entire process

D. None of these

413. Fibrous material is broken by a__________________?
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A. Roll-crusher

B. Ball mill

C. Tube mill

D. Squirrel-cage disintegrator
414. The maximum slope of a belt conveyor can be_____________________?
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A. 15

B. 45

C. 60

D. 30
415. Xanthates are used in the froth floatation process as a/an _______________________?
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A. Frother

B. Collector

C. Activator

D. Conditioner

416. The work index in Bonds law for crushing of solids has the following dimensions__________________?
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A. kW/ton

B. kWh/ton

C. No units (dimensionless)

D. kWh.m1/2/ton

417. Pick out the wrong statement ?
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A. Magnetic separation method can be employed to treat both dry & wet ores

B. Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the

C. imum product size</strong>

D. Gyratory crusher is used for coarse crushing

E. Screens are of stationary, moving and vibratory types

418. Crushing of mineral particles is accomplished in a cage mill, when one or more alloy steel bars are revolved in opposite directions. It is a type of ______________ mill?
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A. Vibratory

B. Impact

C. None of these

D. Roll

419. According to Taggarts rule for selecting between a gyratory crusher and a jaw crusher; the later should be used, if the hourly tonnage to be crushed divided by the square of the gape expressed in cm is less than_______________?
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A. 0.184

B. 1.84

C. 0.0184

D. 0.00184

420. The energy required per unit mass to grind limestone particles of very large size to 100 ?m is 12.7 kWh/ton. An estimate (using Bonds law) of the energy to grind the particles from a very large size to 50 ?m is________________?
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A. 6.35 kWh/ton

B. 25.4 kWh/ton

C. 18 kWh/ton

D. 9.0 kWh/ton

421. Filter aid is used to____________________?
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A. Decrease the pressure drop

B. Increase the rate of filtration

C. Act as a support base for the septum

D. Increase the porosity of the cake
422. Vibrating screens have capacity in the range of ______________ tons/ft2 .mm mesh size?
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A. 5 to 25

B. 0.2 to 0.8

C. 50 to 100

D. 100 to 250

423. Helical screw agitator is used for________________?
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A. Mixing liquids at very high temperature (> 250 C)

B. None of these

C. Blending immiscible liquids

D. Mixing highly viscous pastes
424. Horsepower required for a roll crusher is directly proportional to its__________________?
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A. Reduction ratio

B. Capacity

C. Both A. & B.

D. Neither A. nor B.

425. Size reduction mechanism used in Jaw crushers is__________________?
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A. Impact

B. Attrition

C. Compression

D. Cutting

426. Pick out the correct statement ?
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A. een, is called Work index

B. Plastic chips are called non-cohesive solids

C. Energy required in kwh per ton of product, such that 80% of it passes through a 200 mesh

D. Kicks crushing law is, P/m = K . ln (D? sa/D? sb)

E. Communition is a generic term for size enlargement operation

427. ______________________ balls capable of grinding the feed in a ball mill gives the maximum efficiency ?
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A. Cast iron

B. Maximum size

C. Minimum size

D. Elliptical

428. Screen efficiency is______________________?
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A. None of these

B. Recovery/rejection

C. Rejection

D. Recovery

429. Wet sieving is employed, when the product contains ________________ materials?
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A. Coarse

B. Large quantity of very fine

C. Non-sticky

D. Abrasive

430. _______________ mill is not used for grinding wheat into flour and for milling of cereals & other ?
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A. Pebble

B. etable products.

C. Buhrstone

D. Attrition

E. Roller

431. Shape factor for a cylinder whose length equals its diameter is_________________?
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A. 0.5

B. 2

C. 1

D. 1.5
432. In case of a plate and frame filter press, filtrate flow through the cake follows _______________ flow?
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A. Laminar

B. Plug

C. None of these

D. Turbulent

433. Handling of ashes and similar materials can be done best by a ______________ conveyor?
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A. Belt

B. Ribbon

C. Flight

D. Drag or slat
434. If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is ?s is defined by________________?
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A. ?s = Vp/dpsp

B. ?s = 6 Vp/dpsp

C. ?s = 6 dpSp/Vp

D. ?s = dpSp/Vp

435. _____________________ baffles are provided in ball mills ?
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A. Only two

B. Horizontal

C. None of these

D. No

436. Sedimentation on commercial scale occurs in____________________?
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A. Cyclones

B. Rotary drum filters

C. Thickeners

D. Classifiers

437. The capacity of a classifier in tons of solid/hr is given by (where, A = cross-sectional area in m2, V = rising velocity of fluid in m/sec, S = percentage of solids in the suspension by volume, ? = density of solids in kg/m3)_________________?
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A. 3.6 A.S. ?

B. wer: Option

C. 3.6 A.V.?

D. 3.6 AVS/?

E. 3.6 AVS.?
438. Reduction ratio of crushers is the___________________?
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A. Determining factor for minimum dia of the feed and the product

B. Ratio of discharge opening to feed opening

C. Ratio of feed opening to discharge opening

D. None of these

439. To remove very small amount of tiny solid impurities from liquid, we use a_____________________?
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A. Pressure filter

B. Coagulant

C. Centrifugal filter

D. Vacuum filter

440. Temperature of the product during ultrafine grinding_____________________?
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A. Remain constant

B. Increases

C. Decreases

D. May increase or decrease; depends on the material being ground

441. The basic filtration equation is given as dt/dV = (?/A ?P). [(? .CV/A) + Rm], where, V is volume of the filtrate; A is the filtration area, a is specific cake resistance, ? is viscosity of the filtrate, and C is the concentration of the solids in the feed slurry. In a 20 minutes constant rate filtration, 5 m3 of filtrate was obtained. If this is followed by a constant pressure filtration, how much more time in minutes, it will take for another 5 m3 of filtrate to be produced? Neglect filter medium resistance, Rm; assume incompressible cake ?
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A. 20

B. 30

C. 25

D. 10

442. Pick out the wrong statement?
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A. A dust catcher is simply an enlargement in a pipeline which permits the solids to settle down

B. Wear and tear in wet crushing is more than that in dry crushing of materials

C. to reduction in velocity of the dust laden gas

D. Size enlargement (opposite of size reduction) is not a mechanical operation

E. Recycled coarse material to the grinder by a classifier is termed as circulating load

443. For benefication of iron ore, the most commonly used method is______________?
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A. Froth floatation

B. None of these

C. Jigging & tabling

D. Flocculation

444. ______________ is used for producing a thick suspension from a thin slurry?
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A. Rotary drum vacuum filter

B. Plate and frame filter press

C. Pressure filter thickener

D. Cartridge filter

445. _____________ is the most commonly used filter aid?
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A. Semi-plastic clay

B. Fullers earth

C. Vermiculite

D. Diatomaceous earth