Free Fluid Flow Operations MCQs with Answers

• A. Decreases
• B. Is same as for coarser grinding
• C. Increases
• D. Is 1.5 times that for coarser grinding

Explanation: Finer grinding creates more new surface area, requiring additional energy according to size-reduction relationships such as Rittinger's…

• A. Both B. and C.
• B. Flight conveyor
• C. Screw conveyor
• D. Bucket conveyor

Explanation: Flight conveyors push material with flights attached to an endless chain, while screw conveyors push it with a rotating helical flight…

• A. Ball mill, Jaw crusher, Fluid energy mill
• B. Jaw crusher, Ball mill, Fluid energy mill
• C. Fluid energy mill, Jaw crusher, Ball mill
• D. Fluid energy mill, Ball mill, Jaw crusher

Explanation: A jaw crusher produces the coarsest product, a ball mill produces a finer product, and a fluid-energy mill produces ultrafine particles.

• A. Electrolyte
• B. Surface active agent
• C. Both A. & B.
• D. Neither A. nor B.

Explanation: Electrolytes promote flocculation by compressing the electrical double layer around particles, while suitable surface-active agents can…

• A. Venturi atomiser
• B. Gravity settling chamber
• C. Cyclone separator
• D. Electro-static precipitator

Explanation: An electrostatic precipitator gives particles an electrical charge and collects them on oppositely charged plates, making it highly…

• A. 15°
• B. 30°
• C. 45°
• D. 60°

Explanation: A conventional belt conveyor is generally limited to an inclination of about 30° because steeper slopes cause ordinary bulk solids to…

• A. Cast iron
• B. Minimum size
• C. Maximum size
• D. Elliptical

Explanation: The most efficient charge uses the smallest balls that can still break the feed, because smaller balls provide more contact points and a…

• A. Run upto 1 km
• B. Travel at a speed upto 300 metres/minute
• C. All A., B. and C.
• D. Handle materials upto 5000 tons/hr

Explanation: Belt conveyors can transport material over roughly kilometre-scale distances, operate at speeds near 300 m/min, and handle several…

• A. Cone type agitator
• B. Propeller agitator
• C. Turbine agitator
• D. Radial propeller agitator

Explanation: A cone-type agitator is suitable for dense or fibrous slurries because its sweeping action helps move the bulk material and reduces…

• A. Flight
• B. Screw
• C. Ribbon
• D. Slat or drag

Explanation: Screw conveyors are suited to short-distance movement of bulk solids such as grain, sand, ash and asphalt, while also permitting enclosed…

• A. Np ∝ NRe
• B. Np ∝ √NRe
• C. Np ∝ 1/NRe
• D. Np → constant

Explanation: In the laminar agitation regime, power number follows an inverse relationship with Reynolds number, approximately Np = K/NRe.

• A. 3.6 AVS.ρ
• B. 3.6 A.V.ρ
• C. 3.6 A.S. ρ
• D. 3.6 AVS/ρ
• E. Answer: Option

Explanation: The solid volumetric flow is AVS, and multiplying it by solid density gives kg/s; the factor 3.6 converts this to tonnes per hour.

• A. Jaw crusher
• B. Ball mill
• C. Tube mill
• D. Jet pulveriser

Explanation: A jaw crusher is a primary crusher designed to accept the largest feed among these choices.

• A. Bronze
• B. Flint or porcelain
• C. Stainless steel
• D. Concrete

Explanation: Pebble mills use flint pebbles or porcelain balls instead of iron media, preventing iron contamination of paints, pigments and cosmetics.

• A. Clarification
• B. Sedimentation
• C. Elutriation
• D. Classification

Explanation: Classification separates particles according to their different settling or flow velocities in a fluid.

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

Explanation: Jaw crushers apply compressive force as material is squeezed between the fixed and moving jaws.

• A. ½w2 . δρL (2R + δ)
• B. ½w2 . δ2 . ρL
• C. ½w2 . R2 . ρL
• D. ½w2 . R . ρL(R + 2δ)

Explanation: The centrifugal pressure difference across the film is obtained by integrating ρLω²r from R to R+δ, giving ½ρLω²[(R+δ)²−R²] = ½ω²δρL(2R+δ).

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

Explanation: A colloid mill uses intense shearing and rubbing between closely spaced surfaces, so attrition is the main size-reduction mechanism.

• A. Important in the beginning of filtration
• B. Decreased with the time of filtration
• C. None of these
• D. Independent of pressure drop

Explanation: Cake resistance is initially small because little cake has formed, then increases as solids accumulate on the filter medium.

• A. Pebble
• B. Tube
• C. Rod
• D. Compartment

Explanation: A compartment mill is divided by perforated partitions so that coarse grinding occurs in the first compartment and progressively finer…