me op1 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
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
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
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. D2.5
D. 1/D2.5
C
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
For sizing of fine materials, the most suitable equipment is a
A. trommel
B. grizzly
C. shaking screen
D. vibrating screen
D
Which of the following is not categorised as a “mechanical
operation”?
A. Agitation
B. Filtration
C. Size enlargement
D. Humidification
D
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
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
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
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
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
Which of the following relationships between co-efficient 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
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
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
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
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
Pick out the wrong statement.
A. Close circuit grinding is more economical than open
circuit grinding.
B. Cod oil, beef tallow or aluminium stearates are used as
grinding aids in cement ‘industries’.
C. The equipment used for the removal of traces of solids
from a liquid is called a classifier.
D. Size enlargement is a mechanical operation
exemplified by medicinal tablet making.
C
__________ centrifuge is normally used in sugar mills.
A. Tubular bowl
B. Disc-bowl
C. Suspended batch basket
D. Perforated horizontal basket continuous
C
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
Diatomaceous earth is a/an
A. Explosive
B. filter aid
C. filter medium
D. catalyst
B
The distribution given by microscopic analysis of powder is
A. number
B. length
C. area
D. volume
A
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
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
In washing type plate and frame filter press, the ratio of washing
rate to the final filtrate rate is
A. 4
B. ¼
C. 1
D. ½
B
Ball mills and tube mills with flint or porcelain balls are used for
size reduction of
A. Asbestos
B. Rubber
C. non-metallic ores
D. limestone
C
Size reduction of __________ is accomplished in steam heated
rollers and roll crushers.
A. Resins
B. Gums
C. hard rubber
D. waxes
C
The capacity of a belt conveyor depends upon two factors. If one
is the cross-section of the load, the other is the __________ of
the belt.
A. Speed
B. Thickness
C. Length
D. none of these
A
Which of the following is not a part of the Blake jaw crusher?
A. Hanger
B. Check plates
C. Toggles
D. Pitman
A
If a force greater than that of gravity is used to separate solids &
fluids of different densities, the process is termed as the
A. Sedimentation
B. Flocculation
C. Dispersion
D. Centrifugation
D
Filter aid is used to
A. increase the rate of filtration.
B. decrease the pressure drop.
C. increase the porosity of the cake.
D. act as a support base for the septum.
C
Which of the following mineral dressing operations is termed as
‘comminution’?
A. Panning
B. Spiralling
C. Tabling
D. None of these
D
The capacity of a pneumatic conveying system depends upon
the
A. bulk density of materials.
B. pressure of the conveying air.
C. diameter of the conveying line.
D. all (a), (b) and (c).
D
Gravity settling process is not involved in the working of a
A. Hydrocyclone
B. Classifier
C. dorr-thickener
D. sedimentation tank
A
Froth floatation is the most suitable for treating
A. iron ores
B. sulphide ores
C. quartzite
D. none of these
B
The energy required per unit mass to grind limestone particles
of very large size to 100 μm is 12.7 kWh/ton. An estimate (using
Bond’s law) of the energy to grind the particles from a very large
size to 50 μrn is
A. 6.35 kWh/ton
B. 9.0 kWh/ton
C. 18 kWh/ton
D. 25.4 kWh/ton
C
Which of the following is the most suitable for cleaning of fine
coal dust (<0.5 mm)?
A. Trough washer
B. Baum jig washer
C. Spiral separator
D. Froth floatation
D
Pick out the correct statement:
A. Removal of iron from ceramic material is necessitated
(by magnetic separation method) so as to avoid
discolouration of ceramic products.
B. The operating cost of shaking screen is more than that
of a vibrating screen.
C. Screen capacity does not depend upon the specific
gravity of the minerals.
D. Asphalt is best crushed using toothed roll crusher.
A
Range of compressibility co-efficient of the commercial
compressible cake obtained in filtration operation is
A. to 0.1
B. 0.1 to 0.3
C. 0.2 to 0.8
D. 0.2 to 0.4
C
Highly viscous liquids & pastes are agitated by
A. Propellers
B. turbine agitators
C. multiple blade paddles
D. none of these
C
The value of ‘angle of nip’ is generally about
A. 16°
B. 32°
C. 52°
D. 64°
B
Size reduction of the __________ can be suitably done by ball
mills, crushing rolls and rod mills.
A. metalliferrous ores
B. non-metallic ores
C. basic slags
D. asbestos & mica
A
Sulphuric acid mist is arrested by using a __________ scrubber.
A. packed wet
B. hollow wet
C. venturi
D. co-current
C
the main size reduction operation in ultrafine grinders is
A. cutting
B. attrition
C. compression
D. impact
B
In case of a hammer crusher,
A. crushing takes place by impact breaking.
B. maximum acceptable feed size is 30 cms.
C. reduction ratio can be varied by adjusting the distance
from cage to hammers.
D. all (a), (b) and (c).
D
Jigging is a technique by which different particles can be
A. separated by particle size.
B. separated by particle density.
C. separated by particle shape.
D. mixed.
A