S3 Flashcards
Out of the following size reduction equipments, the maximum feed size can be accepted by the
jaw crusher
Bucket elevators are not suitable for the vertical lifting of __________ materials.
sticky (e.g. clay paste)
The most common filter aid is
diatomaceous earth
For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the __________ filter.
sand
For separation of sugar solution from settled out mud, we use a __________ filter.
centrifugal
The sphericity of a cylinder of 1 mm diameter and length 3 mm is
0.9
Pulverised coal passing through 200 mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 mesh screen will have a dia of __________ mm.
0.30
What is the selectivity index, if the grade of tailings & concentrate is the same?
1
The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a
boundary mixer.
Traces of solids are removed from, liquid in a
clarifier
__________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.
Minimum size
The speed of a rotary drum vacuum filter may be about __________ rpm.
1
Colloid mills achieve size reduction mainly by
attrition
Mesh indicates the number of holes per
linear inch
For achieving maximum capacity of the ball mill, the ball charge should be equal to about __________ percent of the ball mill volume.
50
According to Bond crushing law, the work required to form particle of size ‘D’ from very large feed is (where (S/V)pand (S/V)fare surface to volume ratio of the product and feed respectively).
sqrt (S/V)p
Which of the following gives the work required for size reduction of coal to -200 mesh in a ball mill most accurately?
Rittinger’s law
Electrical energy consumed by a jaw crusher is not a function of the
none of these
Size reduction mechanism used in Jaw crushers is
compression
Trommels employ __________ for screening of materials.
punched plate
A widely used size reduction equipment for __________ is Bradford breaker.
Coal
Ultra centrifuges are used for the separation of __________ solid particles.
colloidal
A. __________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end.
compartment
Size reduction does not occur due to compression in case of
rod mills
According to Taggart’s rule for selecting between a gyratory crusher and a jaw crusher; the later should be used, if the hourly tonnage to be crushed divided by the square of the gape expressed in cm is less than
0.0184
Which of the following represents the plot of filtrate volume versus time for constant pressure filtration?
Parabola
Driving force in case of filtration by a centrifuge is the
centrifugal pressure exerted by the liquid.
Rod mills employed for grinding
all ‘a’, ‘b’ & ‘c’.
Production rate __________ with increased fineness, with a given energy input to the size reduction machine.
decreases
Mixing of light fine powder such as insecticides is done by
impact wheels
Gold ore concentration is mostly done using
Tabling
Run of mine (ROM) coal is crushed by a __________ for use in domestic ovens.
hammer crusher
Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity?
Sphere
The unit of specific cake resistance is
gm/cm2
Size reduction of asbestos and mica is done by
hammer mills
The study on washability of coal is done by using the __________ technique.
heavy media separation
A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is
0.6
__________ conveyor is the most suitable for long distance transportation of cold, non-abrasive granular/irregular shape/fine materials.
Belt
The specific cake resistance for compressible sludges is a function of the pressure drop
over cake
Moisture can be removed from lubricating oil using
tubular centrifuge
Tabling process used for separating two materials of different densities by passing the dilute pulp over a table/deck, which is inclined from the horizontal surface at an angle of about
2 to 5°
Pick out the wrong statement.
Crushing efficiency is the ratio of the energy absorbed by the solid to the surfaces energy created by crushing.
Addition of filter aid to the slurry before filtration is done to …… of the cake.
increase the porosity
Which of the following terminology is not used for size reduction of materials to fine sizes or powders?
Compression
A tube mill as compared to a ball mill
all (a), (b) and (c).
Kick’s law assumes that the energy required for size reduction is proportional to the logarithm of the ratio between the initial and the final diameters. The unit of Kick’s constant is
kW. sec/kg
