S2 Flashcards
Energy consumed for crushing one ton of material ranges from __________ kWh.
0.5 to 1.5
For transporting pasty material, one will use a/an
screw colaveyor
Where the density difference of the two liquid phase to be separated is very small (as in milk cream separator), the most suitable separator is a
disc bowl centrifuge.
A tube mill compared to a ball mill
has a higher length/diameter ratio.
Trommels separate a mixture of particles depending on their
size
Basic slag is not ground in
jaw crushers
Grindability of a material does not depend upon its
size
Shape factor for a cylinder whose length equals its diameter is
1.5
In case of a hammer crusher, the
rotor shaft carrying hammers can be vertical or horizontal.
Dust laden air can be purified using a
cyclone separator
Rittinger’s number designates the new surface created per unit mechanical energy absorbed by the material being crushed. Larger value of Rittinger’s number of a material indicates its
easier grindability
Capacity (in tons/hr) of jaw/gyratory crusher is equal to (where,L= length of the receiving opening, cmS= greater width of the discharge opening, cm)
0.087L.S
Vacuum is applied in __________ zone, in case of a general type continuous rotary drum vacuum filter.
all (a), (b) & (c)
General crushing equation is given by d(rho/m) = - K d Ds / Dns. Bond’s crushing law isobtained by solving this equation for n = __________ and feed of infinite size.
1.5
Which of the follwoing mechanical conveyors does not come under the division ‘scrapers’?
Bucket elevators
__________ mixer is used for devulcanisation of rubber scrap & making water dispersion & rubber solution.
Banbery
Which of the following mechanical conveyors does not come under the division ‘carriers’?
Screw conveyor
Screen capacity is not a function of
atmospheric humidity.
Which of the following is a vacuum filter?
Rotary disc filter
Pine oil used in froth floatation technique acts as a/an
frother
Length/diameter ratio of a ball mill is
< 1
Feed size of ≥ 25 cms can be accepted by
jaw crusher
Which is the most suitable conveyor for transportation of sticky material?
Screw conveyor
The most suitable equipment for removing the fine dust particle (< 1 micron dia.) from air below its dew point will be a/an
electrostatic precipitator
Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is
<10
Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is
1
Filtration of water in a paper mill is done by a/an __________ filter.
open sand
Moore filter is a __________ filter.
leaf
Ball mill is used for
fine grinding
In case of a ball mill,
coarse feed requires a larger ball.
Maximum size reduction in a ball mill is done by the, __________ action.
impact
increasing the capacity of a screen __________ the screen effectiveness.
decreases.
The power number for a stirred tank becomes constant at high Reynolds number. In this limit, the variation of power input with impeller rotational speed (N) is proportional to
N2
Bond crushing law
calls for relatively less energy for the smaller product particles, than does the Rittinger law.
Flow of filtrate through the cake in a plate and frame filter press is best described by the __________ equation.
Kozney-Karman
The controlling resistance in a rotary drum vacuum filter is the __________ resistance.
cake
Which of the following is used for primary crushing of very hard lumpy materials?
Gyratory crusher
Coal is finally pulverised to 200 mesh size for burning in boilers by a
ball mill
Crushing efficiency is the ratio of the
surface energy created by crushing to the energy absorbed by the solid.
The resistance offered by the filter used in a bag filter is proportional to (where,c= dust concentration, ands= particle size)
c/s
Cement clinker is reduced to fine size by a
tube mill
The crushed material received for separation is called feed or
heading
For spheres, volume shape factor is given by
π/6(=V/D3)
Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids ( > 50000 centipoise)?
Helical screw
__________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals.
Selectivity index
The operating speed of a ball mill should be __________ the critical speed.
less than
__________ are used for the separation of coarse particles from a slurry of fine particles.
Classifiers
Fibrous material is broken by a
squirrel-cage disintegrator
__________ is the most suitable for compounding rubber and plastic solids.
Banbery mixer
