Free Chemical Process Principles MCQs with Answers

• A. Both A. and B.
• B. Differential roll speed
• C. Reduction ratio
• D. Neither A. nor B.

Explanation: Reduction ratio changes the work required per unit of crushed material, while differential roll speed changes the relative sliding and…

• A. 16°
• B. 32°
• C. 52°
• D. 64°

Explanation: For roll crushers, the angle of nip is commonly taken as about 32 degrees, representing the largest angle at which the rolls can grip the…

• A. Remains unchanged
• B. Increases
• C. Decreases
• D. May increase or decrease; depends on the machine

Explanation: For a fixed energy input, producing finer particles requires more energy per unit mass, so the throughput or production rate decreases.

• A. 0
• B. ∞
• C. 0.5
• D. 1

Explanation: The selectivity index compares the grade or enrichment of the concentrate with that of the tailings.

• A. Both A. & B.
• B. Type of crushing machine
• C. Feed material
• D. Neither A. nor B.

Explanation: The constants in Kick's, Rittinger's, and Bond's crushing laws are empirical and depend on the material as well as the operating…

• A. Reduction ratio
• B. Both A. & B.
• C. Capacity
• D. Neither A. nor B.

Explanation: Crusher power increases when more material is processed and when a greater size reduction is required.

• A. Coarse
• B. Intermediate
• C. Ultrafine
• D. Fine

Explanation: A colloid mill uses a very small rotor-stator clearance and high shear to produce extremely fine or colloidal dispersions.

• A. Tabling
• B. Elutriation
• C. None of these
• D. Heavy media separation

Explanation: Coal washability is determined by float-sink testing in liquids of controlled density, commonly represented by heavy-media separation.

• A. 0.2 to 0.8
• B. 5 to 25
• C. 50 to 100
• D. 100 to 250

Explanation: Vibrating screens commonly handle about 0.2 to 0.8 tons per hour per square foot per millimetre of mesh size.

• A. Compartment
• B. Cage
• C. Pebble
• D. All tumbling

Explanation: Cage mills are called disintegrators because rapidly rotating cages apply impact and attrition to break particles into smaller sizes.

• A. Jaw
• B. Gyratory
• C. Roll
• D. None of these

Explanation: The angle of nip is the angle between the two roll faces at the point where particles are gripped and drawn into a roll crusher.

• A. Check plates
• B. Crush shaft
• C. Toggles
• D. Jaw plates

Explanation: Jaw plates directly contact and crush the feed, so they experience the greatest abrasion and require frequent replacement.

• A. Apron conveyor
• B. Both B. & C.
• C. Bucket elevator
• D. Pneumatic conveyor

Explanation: A bucket elevator lifts solids mechanically, while a pneumatic conveyor can transport suspended particles vertically through a pipe.

• A. Resins
• B. Gums
• C. Hard rubber
• D. Waxes

Explanation: Hard rubber is tough and elastic, so it is softened with steam and reduced between heated rollers or in roll crushers.

• A. 16°
• B. 32°
• C. 40°
• D. 46°

Explanation: For smooth steel rolls crushing ordinary rock, the usual angle of nip is about 32°.

• A. Multiple blade paddles
• B. Turbine agitators
• C. Propellers
• D. None of these

Explanation: Highly viscous liquids and pastes need broad-surface, high-torque agitation, supplied by multiple-blade paddles.

• A. Grizzly
• B. Vibrating screen
• C. Sharpies centrifuge
• D. Trommel

Explanation: Vibrating screens, grizzlies, and trommels separate solids by size and are screening devices.

• A. Panning
• B. Spiralling
• C. Tabling
• D. None of these

Explanation: Comminution means reducing the size of solid particles by crushing or grinding.

• A. 24
• B. 74
• C. 154
• D. 200

Explanation: A 200-mesh sieve has an opening of approximately 74 micrometres. Mesh number indicates openings per linear inch, so it does not mean an…

• A. Trough washer
• B. Froth floatation
• C. Spiral separator
• D. Baum jig washer

Explanation: Froth flotation is suitable for very fine coal because hydrophobic coal particles attach to air bubbles and float, while mineral…