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WorksheetsChE 3121/L PQ1
Total questions: 30
Worksheet time: 13mins
In screen analysis, notation + 5 mm/ -10 mm means passing through
5 mm screen and retained on 10 mm screen
10 mm screen and retained on 5 mm screen
both 5 mm and 10 mm screens
neither 5 mm nor 10 mm screens
Cumulative Analysis for determining surface is more precise than Differential Analysis because of the
assumption that all particles in single fraction are equal in size
fact that screening is more effective
assumption that all particles in a single fraction are equal in size is not needed
it is easier to express
If we increase the capacity of screen,
its screen effectiveness decreases
its screen effectiveness increases
its screen effectiveness doubles
the screen will be destroyed
What is the mesh number of a screen having 200 mesh per linear inch?
(a)
The ratio of the actual mesh dimension of Taylor series to that of the next smaller screen is
1.414
2
1.189
0.0021
What is this symbol represents, Φs?
(a)
For a spherical particle of diameter Dp, Φs is (a)
The volume surface mean diameter, can be defined as ___
6/ΦsAwPp
6/ΦsAwVp
6/ΦsAwDp
6/ΦsAwSp
A screen is said to be blinded when
oversizes are present in undersize fraction
undersizes are retained in oversize fraction
the screen is plugged with solid particles
its capacity is abruptly increased
Trommels separate a mixture of particles depending on their
size
wet ability
screen size
electrical and magnetic
As particle size is reduced
screening becomes progressively more difficult
screening becomes progressively easier
capacity and effectiveness of the screen is increased
capacity and effectiveness of the screen is decreased
Which of the following screens has the maximum capacity?
grizzlies
trommels
vibrating
oscillating
For sizing of fine materials, the most suitable equipment is a
trommel
vibrating
oscillating
reciprocating
The material passing one screening surface and retained on a subsequent surface is called
plus material
minus material
intermediate material
screens
Odd one out.
Trommels Screens
Consist of cylindrical screen rotating about its axis
revolves at very low speed of 15 to 20 rpm
efficiency is relatively low
used in processing fine separations of materials upto 300 mesh
It represents a particle having the same ratio of surface area to volume as the distribution.
HINT: Also referred as the surface-volume average diameter.
(a)
_ is defined by the ratio of the perimeter if a circle with diameter to the perimeter of the corresponding projection area.
(a)
Traditionally in microscopic methods of size analysis, direct measurements are made on enlarged images of the particles by using a calibrated scale.
TRUE
FALSE
For fine separation, dry sieving is used, but other procedures are necessary for coarser particles.
TRUE
FALSE
Sieves are often referred to their mesh size, which is number of wires per linear unit.
TRUE
FALSE
Screen analysis implies major difficulties, except
with woven-wire screen, the weaving process produces three-dimensional apertures with considerable tolerances, particularly for fine-woven mesh
the mesh is easily damaged in use
the particles must be efficiently presented to the sieve apertures to prevent blinding
high cost on maintenance
_ is the resistance of a material to localized plastic deformation.
(a)
What is the sphericity of a silica sand?
1.0
0.3
0.95
0.65
_ is a frame that transports the vibration from the motor to the screen and holds the motor and screen in place.
(a)
_ have the shape of a truncated cone and are generally mounted with their axes horizontal.
(a)
Differential screen analysis can be presented in _. (as shown)
(a)
Determine its Mesh Number.
46 x 10
48 x 10
50 x 10
52 x 10
Sieve number indicates, the number of meshes in
2.54 mm
25.4 mm
254 mm
0.254 mm
Screening is a method for separating of particles in the basis of
particle size
particle shape
particle density
all of the choices
Elutriation depends upon the movement of a fluid ____ the direction of flow.
in the same
against
perpendicular
none of the choices
