me op 4 Flashcards
_____ mills fall in the category of tumbling mills,
A. Ball and pebble
B. Rod and tube
C. Compartment
D. All
D
Which of the following is not a cutting machine?
A. Dicers
B. Knife cutters
C. Slitters
D. Tube mills
D
Weber number is significant and is concerned with the
A. solid-liquid mixing
B. liquid-liquid mixing
C. dispersion of liquid in liquid
D. suspension of solid in liquid
C
Power consumption during turbulent flow in agitation tank is
proportional to the _______ of the liquid.
A. viscosity
B. thermal conductivity
C. surface tension
D. density
D
Screen efficiency is
A. recovery/rejection
B. recovery
C. rejection
D. none of these
D
Handling of ashes and similar materials can be done best by a
______ conveyor.
A. flight
B. drag or slat
C. belt
D. ribbon
B
200 mesh sieve size corresponds to ____ microns.
A. 24
B. 74
C. 154
D. 200
B
Which of the following must be stored in silos and not in open
yard?
A. Coke breeze
B. High V.M. bituminous coal
C. Sand
D. None of these
B
Apron conveyors are used for
A. heavy loads & short runs
B. small loads & long runs
C. heavy loads & long runs
D. none of these
A
Sedimentation on commercial scale occurs in
A. classifiers
B. thickeners
C. rotary drum filters
D. cyclones
C
With increase in drum speed, in a rotary drum filter, the filtration
rate
A. increases
B. increases linearly
C. decreases
D. is not affected
A
Arrange the following size reduction equipment in the
decreasing order of the average particle size produced by each
of them.
A. Jaw crusher, ball mill, fluid energy mill
B. Ball mill, jaw crusher, fluid energy mill
C. Fluid energy mill, jaw crusher, ball mill
D. Fluid energy mill, ball mill, jaw crusher
A
Capacity of flight conveyor in tons/hr is given by (where, W & D
= width and depth of flight respectively in metre V = speed of the
conveyor, meter/second 𝜌 = bulk density of material, kg/m3)
A. 3.6 W.D.V. ρ
B. 3.6 W.D.V.
C. 3.6 W.V. ρ
D. 3.6 D.V. 𝜌
A
What is the usual value of angle of nip for crushing of ordinary
rock in smooth steel crushing rolls?
A. 16°
B. 32°
C. 40°
D. 46°
B
For grinding of cereals, grains, spices, pigments, saw dust, cork,
etc., the most extensively used size reduction equipment is a
A. Buhrstone mill
B. ball mill
C. crushing rolls
D. hammer mill
A
For a turbine agitated and baffled tank, operating at low
Reynold’s number (based on impeller diameter), the power
number (𝑁) varies with 𝑁 as
A. 𝑁p ∝𝑁re
B. 𝑁p ∝ sqrt(𝑁re)
C. 𝑁p→𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
D. Np ∝1/Nre
D
Which of the following is not accomplished by agitation of liquids
in agitators?
A. Dispersing gas in liquid.
B. Blending of immiscible liquids.
C. Dispersing immiscible liquids in form of emulsion.
D. Suspending solid particles.
B
Which of the following parts of a jaw crusher is subjected to
maximum wear and tear during its operation?
A. Check plates
B. Jaw plates
C. Toggles
D. Crush shaft
B
A 30% (by volume) suspension of spherical sand particles in a
viscous oil has a hindered settling velocity of 4.44 um/s. if the
Richardson Zaki hindered settling index is 4.5, then the terminal
velocity of a sand grain is
A. 0.90 um/s
B. 1 um/s
C. 22.1 um/s
D. 0.02 um/s
B
The specific surface of spherical particles is given by (where D
and ρ are diameter and density of particle).
A. 6/D p
B. 2/D p
C. 4/D p
D. 12/D p
A
Velocity of a small particle of diameter ‘DP’ at a distance ‘r’ from
the rotational axis of a cyclone rotating at an angular speed ‘𝜔’
is given by (the other symbols are as per standard notation)
A. (Dp/18 - ps-p/u) 𝜔^2𝑟
B. (Dp^2/18 - ps-p/u)𝜔𝑟^2
C. (Dp/18 - ps-p/u) 𝜔^2𝑟^2
D. (Dp^2/18 - ps-p/u)𝜔^2𝑟
D
In froth flotation, chemical agent added to cause air adherence
is called
A. collector
B. frother
C. modifier
D. activator
A
The sphericity of a solid particle of cubical shape is
A. 𝜋
B. (𝜋/6)^1/3
C. (𝜋/6)^1/2
D. 𝜋/3
B
Vertical transportation of materials can be done by a/an
A. apron conveyor
B. pneumatic conveyor
C. bucket elevator
D. both b & c
D
In a roll crusher, the specific power consumption and the
production rate is affected by the
A. reduction ratio
B. differential roll speed
C. both a and b
D. neither a nor b
C
For Indian standard (IS) screens, the mesh number is equal to
its aperture size expressed to the nearest deca-micron (0.01
mm). aperture width of IS screen of mesh number 50 will be
approximately ______ microns.
A. 5
B. 50
C. 500
D. 5000
C
A Cottrell precipitator makes use of the __ for dusty air cleaning.
A. electric spark
B. corona discharge
C. alternating current
D. none of these
B
Pick out the correct statement.
A. Plastic chips are called non-cohesive solids.
B. Kick’s crushing law is, 𝑃/𝑚=𝐾∙ln(Dsa/Dsb)
C. Comminution is a generic term for size enlargement
operation.
D. Energy required in kWh per ton of product, such that
80% of it passes through a 200 mesh screen, is called
‘Work index’.
B
If radius of a batch basket centrifuge is halved & the rpm is
doubled, then the
A. linear speed of the basket is doubled.
B. linear speed of the basket is halved.
C. centrifugal force is doubled.
D. capacity of centrifuge is increased.
C
The ratio of the area of openings in one screen (Taylor series) to
that of the openings in the next smaller screen is
A. 1.5
B. 1
C. √2
D. None of these
D
Compressibility coeff. for an absolutely compressible cake is
A. 0
B. 1
C. 0 to 1
D. ∞
B
Mixing of plastic solids is generally facilitated by
A. dispersion
B. mastication
C. kneading
D. none of these
C
The mechanism of size reduction by a hammer mill is by impact
and attrition between the
A. grinding element &the housing
B. feed particles
C. both a and b
D. neither a nor b
C
Which of the following is not an industrial screening equipment?
A. Sharpies centrifuge
B. Vibrating screen
C. Grizzly
D. Trommel
A
Which of the following is not a wet classifier?
A. Sharpies supercentrifuge
B. Hydrocyclones
C. Dorr Oliver rake classifier
D. None of these
D
Helical screw agitator is used for
A. mixing highly viscous pastes
B. blending immiscible liquids
C. mixing liquids at very high temperature (> 250°c).
D. none of these
A
For Raschig rings, the sphericity is
A. 0.5
B. 1
C. <1
D. √3
C
_______ mills are termed as disintegrators.
A. Cage
B. Compartment
C. Pebble
D. All tumbling
A
Supporting legs of a plate and frame filter is normally made of
A. stainless steel
B. cast iron
C. high speed steel
D. wooden plank
B
The cumulative mass fraction of particles smaller than size dj for
a collection of Ni particles of diameter di and mass mi (i = 1, 2, 3,
….. ∞) is given by
A. ∑ 𝑁𝑑^3 /∑ 𝑁𝑑^3
B. ∑ 𝑁𝑚𝑑^3 /∑ 𝑁𝑚𝑑^3
C. ∑ 𝑁𝑚𝑑^2 /∑ 𝑁𝑚𝑑^2
D. ∑ 𝑁𝑚𝑑/∑ 𝑁𝑚𝑑
B
Wet grinding in a revolving mill _______ as compared to dry
grinding.
A. gives less wear on chamber walls
B. requires more energy
C. increases capacity
D. complicates handling of the product
C
The grinding in a hammer crusher takes place due to the
A. attrition
B. impact
C. both a & b
D. neither a nor b
C
A compressible cake has the
A. maximum porosity at the upstream side.
B. maximum porosity at the filter medium.
C. same porosity through the cake thickness.
D. none of these
A
Which of the following is not used as a filter medium in case of
corrosive liquids?
A. Nylon
B. Glass cloth
C. Metal cloth of Monel or stainless steel
D. Cotton fabric
D