Engineering Questions with Answers - Multiple Choice Questions
Mechanical Operations MCQ’s – Mixing Equipments
Ore concentration by jigging is based on the difference in the _______ of the particles.
a) Specific gravities
b) Wet ability
Explanation: Jigging is a method of gravitational preparation of natural resources, based on separation of mineral mixture on density in vertically oscillating water stream.
Traces of liquid tar fog present in coke oven gas is separated using _________
a) Electrostatic precipitator
b) Cyclone separator
d) Vibrating screen
Explanation: The traces cannot be separated by a normal means that is why, it is charged with a static charger and then separated in an electrostatic separator.
In case of revolving mill, wet grinding compared to dry grinding ___________
a) Requires more energy
b) Has less capacity
c) Complicates handling and classification of the product
d) Effects the motion of the ball
Explanation: Wet grinding sustainably require less motion of the ball as they are already mixed with a medium.
Froth floatation is the most suitable for treating _________
a) Iron ores
b) Supplied ores
d) Iron ores
Explanation: Supplied ores can easily be separated using difference in the settling velocity, and thus can be easily separated.
For beneficiation of iron ore, the most commonly used method is ________
b) Froth floatation
c) Jigging and tabling
Explanation: Jigging involves the separation due to specific gravity and tabling involves concentration of pulp material thus best for iron ore sepration.
Screen capacity is expressed in terms of ________
Explanation: The capacity of screen is represented by amount of material per unit time and required are, i.e. Tons/hr-ft2.
The energy consumed by ball mill depends on _________
a) Its speed
d) Electrical and magnetic properties
Explanation: Energy depends on the consumption of electrical energy and if magnetic field is involved then magnetic properties also varies with energy.
Ultrafine grinders operate principally by _________
a) Slow compression
d) Cutting action
Explanation: Ultrafine grinders are involved for ultrafine particles which are below the range of 10 micrometer and involves attrition as phenomenon.
Size measurement of ultrafine particles can be best expressed in terms of _______
b) Screen size
d) Surface area per unit mass
Explanation: The measurement of ultrafine particles are usually expressed as in surface area per unit mass and secondarily in microns.
A screen is said to be blinded when the _________
a) Oversized is present in the undersize fraction
b) Undersized is present in the oversize fraction
c) Screen is plugged with solid particles
d) Screen capacity is abruptly increased
Explanation: When the oversized is present in the undersize the screen is said to be inefficient, and can cause defect in separation.