Section 1 Flashcards
Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a ________ conveyor.
a. flight
b. slat or drag
c. ribbon
d. screw
d. screw
Equivalent diameter of a particle is the diameter of the sphere having the same
a. ratio of surface to volume as the actual volume.
b. ratio of volume to surface as the particle.
c. volume as the particle.
d. none of these.
a. ratio of surface to volume as the actual volume.
If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its
surface area, then its sphericity is Φs is defined by
a. Φs = 6 Vp/dp sp
b. Φs = Vp/dp sp
c. Φs = 6 dp Sp/Vp
d. Φs = dp Sp/Vp
a. Φs = 6 Vp/dp sp
Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill )
a. D
b. 1/D
c. D^2.5
d. 1/D^2.5
c. D^2.5
Pick out the wrong statement.
a. Recycled coarse material to the grinder by a classifier is termed as circulating
load.
b. Wear and tear in wet crushing is more than that in dry crushing of materials.
c. Size enlargement (opposite of size reduction) is not a mechanical operation.
d. A ‘dust catcher’ is simply an enlargement in a pipeline which permits the solids
to settle down due to reduction in velocity of the dust laden gas.
c. Size enlargement (opposite of size reduction) is not a mechanical operation.
In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as
the
a. square root of the velocity.
b. square of the viscosity.
c. filtration time only.
d. washing time only.
a. square root of the velocity.
For sizing of fine materials, the most suitable equipment is a
a. trommel
b. grizzly
c. shaking screen
d. vibrating screen
d. vibrating screen
Which of the following is not categorised as a “mechanical operation” ?
a. Agitation
b. Filtration
c. Size enlargement
d. Humidification
d. Humidification
Which of the following is a pressure filter ?
a. Leaf filter (Moore filter).
b. Plate and flame filter.
c. Rotary drum filter.
d. Sand filter.
b. Plate and flame filter.
Tabular bowl centrifuges as compared to disk bowl centrifuges
a. operate at higher speed.
b. employ bowl of larger diameter.
c. can not be operated under pressure/vacuum.
d. can’t be used for separation of fine suspended solids from a liquid.
a. operate at higher speed.
Pebble mills are tumbling mills widely used for grinding in the manufacture of paints &
pigments and cosmetic industries, where iron contamination in the product is highly
objectionable. Pebbles used in pebble mill are made of
a. bronze
b. stainless steel
c. flint or porcelain
d. concrete
c. flint or porcelain
Filter aids like asbestos, kieselguhr, diatomaceous earth etc. are used to increase the porosity of the final filter cake & reducing the cake resistance during filtration. Filter aid is
a. added to the feed slurry.
b. precoated on the filter medium prior to filtration.
c. separated from the cake by dissolving solids or by burning it off.
d. all ‘a’, ‘b’&’c’.
d. all ‘a’, ‘b’&’c’.
Which of the following relationships between co-efficinet of friction (μ) between rock &
roll and a (half of the angle of nip) of the particle to be crushed is correct ?
a. μ > tan α
b. μ ≥ tan α
c. μ > tan 2α
d. μ ≤ tan α
b. μ ≥ tan α
Pick out the wrong statement pertaining to the roll crushers.
a. Maximum feed size determines the required roll diameter.
b. For hard material’s crushing, the reduction ratio should not exceed 4.
c. Both the rolls run necessarily at the same speed.
d. Reduction ratio and differential roll speed affect production rate & energy consumed per unit of surface produced.
c. Both the rolls run necessarily at the same speed
Which of the following is not an ultrafine grinder (colloid mill)?
a. Micronizers
b. Agitated mills and fluid energy mills
c. Toothed roll crusher
d. Hammer mills with internal classification
c. Toothed roll crusher
Two particles are called to be equal settling, if they are having the same.
a. size.
b. specific gravity.
c. terminal velocities in the same fluid & in the same field of force.
d. none of these.
c. terminal velocities in the same fluid & in the same field of force.
Which of the following is the most suitable for handling fibrous and dense slurries ?
a. Propeller agitator
b. Cone type agitator
c. Turbine agitator
d. Radial propeller agitator
b. Cone type agitator
________centrifuge is normally used in sugar mills.
a. Tubular bowl
b. Disc-bowl
c. Suspended batch basket
d. Perforated horizontal basket continuous
c. Suspended batch basket
Solid particles separation based on the difference in their flow velocities through fluids is termed as the
a. clarification
b. classification
c. elutriation
d. sedimentation
b. classification
Diatomaceous earth is a/an
a. explosive
b. filter aid
c. filter medium
d. catalyst
b. filter aid
The distribution given by microscopic analysis of powder is
a. number
b. length
c. area
d. volume
a. number
Number of particles in a crushed solid sample is given by (where, m = mass of particles
in a sample, Vp = volume of one particle, ρ= density of particles)
a. m/ρ . Vp
b. m. ρ/Vp
c. m . Vp/ρ
d. Vp/m . ρ
a. m/ρ . Vp
For a non-spherical particle, the sphericity
a. is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle.
b. has the dimension of length.
c. is always less than 1.
d. is the ratio of volume of a sphere having the same surface area as the particle
to the actual volume of the particle.
a. is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle.
In washing type plate and frame filter press, the ratio of washing rate to the final filtrate
rate is
a. 4
b. 1/4
c. 1
d. 1/2
b. 1/4
