S8 Flashcards
Screen efficiency is
none of these
For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a
Buhrstone mill
Handling of ashes and similar materials can be done best by a __________ conveyor.
drag or slat
Which of the following must be stored in silos and not in open yard?
High V.M. bituminous coal
Apron conveyors are used for
heavy loads & short runs.
Sedimentation on commercial scale occurs in
rotary drum filters
With increase in drum speed, in a rotary drum filter, the filtration rate
increases
Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them.
Jaw crusher, Ball mill, Fluid energy mill
200 mesh seive size corresponds to __________ microns.
74
What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls?
32°
For a turbine agitated and baffled tank, operating at low Reynold’s number (based on impeller diameter), the power number (Np) varies withNReas
Np α 1/NRe
Which of the following is not accomplished by agitation of liquids in agitators?
Blending of immiscible liquids.
Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation?
Jaw plates
A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 μm/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is
1 μm/s
The specific surface of spherical particles is given by (whereDand ρ are diameter and density of particle).
6 / D . ρ
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)
(Dp^2 /18 . ρs - ρ / μ) ω^2 r
In froth floatation, chemical agent added to cause air adherence is called
collector
The sphericity of a solid particle of cubical shape is
(π/6)^1/3
A cottrel precipitator makes use of the __________ for dusty air cleaning.
corrona discharge
Pick out the correct statement.
Kick’s crushing law is, P/m = K . ln (Dsa/Dsb)
If radius of a batch basket centrifuge is halved & the r.p.m. is doubled, then the
centrifugal force is doubled.
The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is
none of these
Compressibility co-efficient for an absolutely compressible cake is
1
Mixing of plastic solids is generally facilitated by
kneading
Which of the following is not an industrial screening equipment?
Sharpies centrifuge
Which of the following is not a wet classifier?
None of these
Helical screw agitator is used for
mixing highly viscous pastes.
For raschig rings, the sphericity is
<1
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.
500
__________ mills are termed as disintegrators.
Cage
Supporting legs of a plate and frame filter is normally made of
cast iron
The cummulative mass fraction of particles smaller than size djfor a collection of Ni particles of diameter diand mass mi (i = 1, 2, 3, …… ∞) is given by
∑ i = 1 j Ni mi di^3 / ∑ i = 1 ∞ Ni mi di^3
Wet grinding in a revolving mill __________ as compared to dry grinding.
increases capacity
A compressible cake has the
maximum porosity at the upstream side.
Which of the following is not used as a filter medium in case of corrosive liquids?
Cotton fabric
In ball mill operation, the feed size (Dfin meters) and the ball diameter (Dbin metres) are related as ( where,K= grindability constant (varying from 0.9 to 1.4 in increasing order of hard ness))
Db^2=K.Df
Pine oil and cresylic acid are used as ________ in the froth floatation process.
frother
Grinding characteristic of a material is given by its
HGI
Which of the following is not a non-metalliferous mineral?
Cassiterrite
Filter medium resistance is important during the __________ of filtration.
early stages.
Float and sink test determines the possibility of cleaning of coal by a process based on the
gravity separation
Mixer used for rubber compounding is
banbury internal mixer
__________ baffles are provided in ball mills.
Horizontal
For spheres, the specific surface shape factor is given by
AD/V
__________ mill is not used for grinding wheat into flour and for milling of cereals & other vegetable products.
Pebble
In case of a hammer crusher, the final product size depends on the
all (a), (b) and (c).
