Free Fluid Flow Operations MCQs with Answers

• A. Solid-liquid mixing
• B. Liquid-liquid mixing
• C. Suspension of solid in liquid
• D. Dispersion of liquid in liquid

Explanation: The Weber number compares inertial forces with surface-tension forces, so it is especially important when droplets are formed or broken…

• A. Parabola
• B. Straight line
• C. Hyperbola
• D. Exponential curve

Explanation: At constant pressure, cake resistance increases as filtrate accumulates, giving the conventional parabolic filtration curve rather than a…

• A. Enters the cyclone from the top
• B. Both B. and C.
• C. Develops a helical motion inside the chamber
• D. Is admitted tangentially at high velocity

Explanation: Dust-laden gas enters a cyclone tangentially at high velocity, creating a helical vortex that drives particles toward the wall by…

• A. Cartridge filter
• B. Rotary drum vacuum filter
• C. Pressure filter thickener
• D. Plate and frame filter press

Explanation: A thickener separates solids by gravity settling and produces a concentrated underflow from a dilute slurry.

• A. 1
• B. 50
• C. 100
• D. 500

Explanation: Rotary drum vacuum filters rotate slowly so that cake formation, washing, dewatering, and discharge can occur during each revolution.

• A. Bulk density of materials
• B. All A., B. and C.
• C. Diameter of the conveying line
• D. Pressure of the conveying air

Explanation: Pneumatic conveying capacity is affected by the solids' bulk density, the pressure and available air flow, and the conveying-line…

• A. Tubular bowl
• B. Disc-bowl
• C. Suspended batch basket
• D. Perforated horizontal basket continuous

Explanation: Sugar crystals are commonly separated from mother liquor in suspended batch-basket centrifuges, which allow the basket to be charged…

• A. Can't be operated under pressure/vacuum
• B. Employ bowl of larger diameter
• C. Operate at higher speed
• D. Can't be used for separation of fine suspended solids from a liquid

Explanation: Tubular-bowl centrifuges use a small-diameter bowl and therefore operate at higher rotational speeds than disc-bowl centrifuges.

• A. 0.01 to 0.1
• B. 0.1 to 0.3
• C. 0.2 to 0.4
• D. 0.2 to 0.8

Explanation: The compressibility coefficient of commercial filter cakes commonly lies around 0.2 to 0.8.

• A. Linear speed of the basket is doubled
• B. Centrifugal force is doubled
• C. Linear speed of the basket is halved
• D. Capacity of centrifuge is increased

Explanation: Centrifugal force varies as N²r. Doubling the rotational speed multiplies it by four, while halving the radius multiplies it by one-half…

• A. Cutting
• B. Compression
• C. Attrition
• D. Impact

Explanation: Ultrafine grinding requires particles to rub against one another or the grinding surface, so attrition is the dominant mechanism.

• A. Dispersion
• B. Mastication
• C. None of these
• D. Kneading

Explanation: Kneading repeatedly deforms and folds highly viscous plastic material, distributing one solid throughout another.

• A. Increases
• B. Increases linearly
• C. Decreases
• D. Is not affected

Explanation: Increasing drum speed gives more filtering cycles per unit time, so the filter capacity or filtration rate generally increases, within the…

• A. Classifier
• B. Hydrocyclone
• C. Dorr-thickener
• D. Sedimentation tank

Explanation: A hydrocyclone separates particles mainly by centrifugal action produced by the swirling fluid, not by gravity settling.

• A. Asbestos
• B. Rubber
• C. Non-metallic ores
• D. Limestone

Explanation: Flint or porcelain balls are hard, wear-resistant grinding media used to reduce non-metallic ores while minimising metallic contamination.

• A. Abrasion index
• B. Angle of repose
• C. Shatter index
• D. HGI

Explanation: The Hardgrove Grindability Index (HGI) indicates how readily a material can be pulverised, so it characterises grinding behaviour.

• A. 5
• B. 50
• C. 500
• D. 5000

Explanation: Using the stated approximation, mesh 50 corresponds to 50 decamicrons: 50 × 0.01 mm = 0.50 mm, or about 500 microns.

• A. 0.007
• B. 0.30
• C. 50
• D. 0.014

Explanation: A 50-mesh opening is approximately 0.30 mm, whereas a 200-mesh opening is about 0.074 mm.

• A. Ball and pebble
• B. Rod and tube
• C. Compartment
• D. All A., B. & C.

Explanation: Tumbling mills reduce size by lifting and dropping or cascading the grinding charge as the shell rotates.

• A. Belt
• B. Bucket
• C. Screw
• D. Apron

Explanation: A belt conveyor is suited to long-distance movement of cold, nonabrasive solids, including granular, irregular and fine materials.