Mechanical Operations Flashcards
1
Q
Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a __________ conveyor.
A
screw
2
Q
Equivalent diameter of a particle is the diameter of the sphere having the same
A
ratio of surface to volume as the actual volume
3
Q
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
4
Q
Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill )
A
D^2.5
5
Q
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.
A
Size enlargement (opposite of size reduction) is not a mechanical operation
6
Q
In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the
A
square root of the velocity
7
Q
For sizing of fine materials, the most suitable equipment is a
A
vibrating screen
8
Q
Which of the following is not categorised as a “mechanical operation” ?
a. Agitation
b. Filtration
c. Size enlargement
d. Humidification
A
Humidification
9
Q
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.
A
Plate and flame filter
10
Q
Tabular bowl centrifuges as compared to disk bowl centrifuges
A
operate at higher speed
11
Q
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
flint or porcelain
12
Q
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’.
A
all ‘a’, ‘b’&’c’
13
Q
Which of the following relationships between co-efficinet 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
A
μ ≥ tan α
14
Q
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.
A
Both the rolls run necessarily at the same speed
15
Q
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
A
Toothed roll crusher
16
Q
Two particles are called to be equal settling, if they are having the same.
A
terminal velocities in the same fluid & in the same field of force
17
Q
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
A
Cone type agitator
18
Q
__________ centrifuge is normally used in sugar mills.
A
Suspended batch basket
19
Q
Solid particles separation based on the difference in their flow velocities through fluids is termed as the
A
classification
20
Q
Diatomaceous earth is a/an
A
filter aid
21
Q
The distribution given by microscopic analysis of powder is
A
number
22
Q
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
23
Q
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
24
Q
In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is
A
1/4
25
Ball mills and tube mills with flint or porcelain balls are used for size reduction of
non-metallic ores
26
Size reduction of __________ is accomplished in steam heated rollers and roll crushers.
hard rubber
27
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.
speed
28
Which of the following is not a part of the Blake jaw crusher?
a. Hanger
b. Check plates
c. Toggles
d. Pitman
Hanger
29
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
centrifugation
30
Filter aid is used to
increase the porosity of the cake.
31
Which of the following mineral dressing operations is termed as 'comminution'?
a. Panning
b. Spiralling
c. Tabling
d. None of these
None of these
32
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).
all (a), (b) and (c)
33
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.
The equipment used for the removal of traces of solids from a liquid is called a classifier
34
Gravity settling process is not involved in the working of a
hydrocyclone
35
Froth floatation is the most suitable for treating
sulphide ores
36
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
18 kWh/to
37
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
Froth floatation
38
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.
The operating cost of shaking screen is more than that of a vibrating screen
39
Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is
0.2 to 0.8
40
Highly viscous liquids & pastes are agitated by
multiple blade paddles
41
The value of 'angle of nip' is generally about
32°
42
Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.
metalliferrous ores
43
Sulphuric acid mist is arrested by using a __________ scrubber.
venturi
44
The main size reduction operation in ultrafine grinders is
attrition
45
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).
all (a), (b) and (c).
46
Jigging is a technique by which different particles can be
separated by particle size.
47
Crushing of mineral particles is accomplished in a 'cage mill', when one or more alloy steel bars are revolved in opposite directions. It is a type of __________ mill.
impact
48
Balls for ball mills are never made of
lead
49
200 mesh screen means 200 openings per
inch
50
__________ is the most commonly used 'filter aid'.
Diatomaceous earth
51
Energy consumed for crushing one ton of material ranges from __________ kWh.
0.5 to 1.5
52
For transporting pasty material, one will use a/an
screw colaveyor
53
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.
54
A tube mill compared to a ball mill
has a higher length/diameter ratio.
55
Trommels separate a mixture of particles depending on their
size
56
Basic slag is not ground in
jaw crushers
57
Grindability of a material does not depend upon its
size
58
Shape factor for a cylinder whose length equals its diameter is
1.5
59
In case of a hammer crusher, the
rotor shaft carrying hammers can be vertical or horizontal.
60
Dust laden air can be purified using a
cyclone separator
61
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
62
Capacity (in tons/hr) of jaw/gyratory crusher is equal to (where, L = length of the receiving opening, cm S = greater width of the discharge opening, cm)
0.087 L.S
63
Vacuum is applied in __________ zone, in case of a general type continuous rotary drum vacuum filter.
a. filtering
b. washing
c. drying
d. all (a), (b) & (c)
all (a), (b) & (c)
64
Which of the follwoing mechanical conveyors does not come under the division 'scrapers' ?
a. Ribbon conveyor
b. Flight conveyor
c. Bucket elevators
d. Drag conveyor.
Bucket elevators
65
__________ mixer is used for devulcanisation of rubber scrap & making water dispersion & rubber solution.
Banbery
66
Which of the following mechanical conveyors does not come under the division 'carriers'?
Screw conveyor
67
Screen capacity is not a function of
atmospheric humidity
68
Which of the following is a vacuum filter?
Rotary disc filter
69
Pine oil used in froth floatation technique acts as a/an
frother
70
Length/diameter ratio of a ball mill is
< 1
71
Feed size of ≥ 25 cms can be accepted by
jaw crusher
72
Which is the most suitable conveyor for transportation of sticky material?
a. Apron conveyor
b. Belt conveyor
c. Screw conveyor
d. Pneumatic conveyor
Screw conveyor
73
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
74
Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is
<10
75
Filtration of water in a paper mill is done by a/an __________ filter.
open sand
76
Moore filter is a __________ filter.
leaf
77
Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is
1
78
Ball mill is used for
fine grinding
79
In case of a ball mill,
coarse feed requires a larger ball
80
Maximum size reduction in a ball mill is done by the, __________ action.
impact
81
Increasing the capacity of a screen __________ the screen effectiveness.
decreases.
82
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^
83
Bond crushing law
calls for relatively less energy for the smaller product particles, than does the Rittinger law.
84
Flow of filtrate through the cake in a plate and frame filter press is best described by the __________ equation.
Kozney-Karman
85
The controlling resistance in a rotary drum vacuum filter is the __________ resistance.
cake
86
Which of the following is used for primary crushing of very hard lumpy materials?
Gyratory crusher
87
Coal is finally pulverised to 200 mesh size for burning in boilers by a
ball mill
88
Crushing efficiency is the ratio of the
surface energy created by crushing to the energy absorbed by the solid.
89
The resistance offered by the filter used in a bag filter is proportional to (where, c = dust concentration, and s = particle size )
c/s
90
Cement clinker is reduced to fine size by a
tube mill
91
The crushed material received for separation is called feed or
heading
92
For spheres, volume shape factor is given by
π/6(=V/D3)
93
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
94
__________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals.
Selectivity index
95
The operating speed of a ball mill should be __________ the critical speed.
less than
96
__________ are used for the separation of coarse particles from a slurry of fine particles.
Classifiers
97
Fibrous material is broken by a
squirrel-cage disintegrator
98
__________ is the most suitable for compounding rubber and plastic solids.
Banbery mixer
99
Out of the following size reduction equipments, the maximum feed size can be accepted by the
jaw crusher
100
Bucket elevators are not suitable for the vertical lifting of __________ materials.
sticky (e.g. clay paste)
101
The most common filter aid is
diatomaceous earth
102
For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the __________ filter.
sand
103
For separation of sugar solution from settled out mud, we use a __________ filter.
centrifugal
104
The sphericity of a cylinder of 1 mm diameter and length 3 mm is
0.9
105
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.
0.3
106
What is the selectivity index, if the grade of tailings & concentrate is the same?
1
107
The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a
boundary mixer.
108
Traces of solids are removed from, liquid in a
clarifier
109
_________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.
Minimum size
110
The speed of a rotary drum vacuum filter may be about __________ rpm.
1
111
Colloid mills achieve size reduction mainly by
attrition
112
Mesh indicates the number of holes per
linear inch
113
For achieving maximum capacity of the ball mill, the ball charge should be equal to about __________ percent of the ball mill volume.
50
114
According to Bond crushing law, the work required to form particle of size 'D' from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively).
sqrt(S/V)p
115
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
116
Electrical energy consumed by a jaw crusher is not a function of the
a. average feed size
b. average product size
c. machine capacity
d. none of these
none of these
117
Size reduction mechanism used in Jaw crushers is
compression
118
Trommels employ __________ for screening of materials.
punched plate
119
A widely used size reduction equipment for __________ is Bradford breaker.
coal
120
Ultra centrifuges are used for the separation of __________ solid particles.
colloidal
121
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
122
Size reduction does not occur due to compression in case of
rod mills
123
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
124
Which of the following represents the plot of filtrate volume versus time for constant pressure filtration?
Parabola
125
Driving force in case of filtration by a centrifuge is the
centrifugal pressure exerted by the liquid.
126
Rod mills employed for grinding
a. employ a steel shell having L/D ratio of 1.5 to 3.0.
b. is useful for handling sticky materials.
c. employ steel rods of 2-12 cms diameter extending over full length of the mill.
d. all 'a', 'b' & 'c'.
all 'a', 'b' & 'c'.
127
Production rate __________ with increased fineness, with a given energy input to the size reduction machine.
decreases
128
Gold ore concentration is mostly done using
tabling
129
Mixing of light fine powder such as insecticides is done by
impact wheels
130
Run of mine (ROM) coal is crushed by a __________ for use in domestic ovens.
hammer crusher
131
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
132
The unit of specific cake resistance is
gm/cm2
133
Size reduction of asbestos and mica is done by
hammer mills
134
The study on washability of coal is done by using the __________ technique.
heavy media separation
135
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
136
__________ conveyor is the most suitable for long distance transportation of cold, non-abrasive granular/irregular shape/fine materials.
Belt
137
The specific cake resistance for compressible sludges is a function of the pressure drop
over cake
138
Moisture can be removed from lubricating oil using
tubular centrifuge
139
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
140
Pick out the wrong statement.
a. Gape is the greatest distance between the crushing surfaces or the jaws.
b. The angle of nip (2α) is the angle between roll faces at the level where they will j ust take hold of a particle and draw it in the crushing zone.
c. Crushing efficiency is the ratio of the energy absorbed by the solid to the surfaces energy created by crushing.
d. Reduction ratio is the ratio of the maximum size of the particles in the feed to that in the product.
Crushing efficiency is the ratio of the energy absorbed by the solid to the surfaces energy created by crushing.
141
Addition of filter aid to the slurry before filtration is done to ...... of the cake.
increase the porosity
142
Which of the following terminology is not used for size reduction of materials to fine sizes or powders?
Compression
143
A tube mill as compared to a ball mill
a. employs smaller balls.
b. gives finer size reduction but consumes more power.
c. has larger length/diameter ratio (>2 as compared to 1 for ball mill).
d. all (a), (b) and (c).
all (a), (b) and (c).
144
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
145
Which of the following gives the crushing energy required to create new surface?
Rittinger's law
146
In filtration, the use of 'filter aid' helps in
deplugging the filter medium.
147
Gizzlies are used for separating __________ solids.
fine
148
Which of the following clay mixing devices is vacuum operated for deairation of clay?
Pug mil
149
Pick out the material having minimum Rittinger's number.
Quartz
150
__________ mills are termed as impactors.
Hammer
151
In case of a revolving mill, wet grinding compared to dry grinding
a. requires more energy.
b. has less capacity.
c. complicates handling & classification of the product.
d. none of these.
none of these.
152
To get a fine talc powder from its granules, the equipment used is
ball mill
153
For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is
230
154
Higher is the mesh number, smaller will be the aperture size of the screen. It means that the aperture size of a 200 mesh screen will be smaller than that of 20 mesh screen. This is valid for
a. British standard screens.
b. German standard screens (DIN 1171) etc.
c. American standard screens (ASTM and Tyler standard screens).
d. all (a), (b) and (c).
all (a), (b) and (c).
155
Pick out the wrong statement.
a. Cummulative analysis for determining surface area is preferred over differential analysis, because of the assumption that "all particles in a simple fraction equal in size" is not needed for cummulative anslysis unlike differential anlaysis.
b. A gate diagram is a plot of cummulative percent by weight undersize vs. the reciprocal of diameter, in which the area beneath the curve represents the surface.
c. Capacity of crusher in choke feeding is increased.
d. Rolling of pebbles/balls from top to bottom of the heap in tumbling mills is called 'cascading and throwing of the balls through the air to the toe of the heap is called 'cataracting'.
Capacity of crusher in choke feeding is increased.
156
Which of the following size reduction equipments employs mainly attrition for ultrafine grinding?
a. Jet mills
b. Fluid energy mill
c. Micronizer
d. all (a), (b) and (c)
all (a), (b) and (c)
157
Tank filter (e.g., Nutsch filter) is
used for small scale filtration work.
158
In bag filters, filter fabrics are never made of
metallic wire woven mesh
159
Use of 'grinding aids' is done in __________ grinding.
dry
160
Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)
D
161
Which of the following is the most suitable filter for separation of abrasive solids suspended in a corrosive liquid?
Vacuum filter
162
All resistances during washing of cake
remain constant
163
A __________ mixer resembles a ball mill without balls.
tumbling
164
__________ conveyor is the most suitable for short distance transportation of non-abrasive loose materials like garbage, grain, food wastes etc.
Flight
165
As the product becomes finer, the energy required for grinding
increases
166
Gyratory crushers compared to the reciprocating jaw crushers
have greater capacity per unit of discharge area.
167
At low Reynold's number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied:
Po = ρ/ρN3 D5 : Power number
Re = ρ N D2/μ: Reynold's number
N is the impeller rotational speed, and D is the impeller diameter.
Po ∝ Re-1.0
168
Which of the following grinding mills has the horizontally arranged rods as the grinding elements thereby delivering more uniform granular products with minimum fines?
Rod mill
169
Rittinger's crushing law states that
work required in crushing is proportional to the new surface created.
170
Sphericity of pulverised coal is
<1
171
The reduction ratio for fine grinders is
as high as 100
172
Which of the following is the hardest material?
a. Calcite
b. Quartz
c. Corundum
d. Gypsum
Corundum
173
General mechanism of size reduction in intermediate and fine grinder is by
impact and attrition.
174
A straight line is obtained on plotting reciprocal of filtration rate vs. the volume of filtrate for __________ flow of filtrate.
incompressible cake and laminar
175
The work index in Bond's law for crushing of solids has the following dimensions
kWh/ton
176
Ore concentration by jigging is based on the difference in the __________ of the particles.
specific gravities
177
Size measurement of ultrafine particles can be best expressed in terms of
surace area per unit mass
178
Reduction ratio of crushers is the
ratio of feed opening to discharge opening.
179
Which is a secondary crusher for a hard & tough stone?
Cone crusher
180
Which of the following equations is Rittinger's crushing law ? (where P = power required by the machine, m = feed rate, k = a constant = volume surface mean diameter of feed & product respectively.)
P/m = K . (1/Dsb - 1/Dsa)
181
Cyclones are used primarily for separating
solids from fluids
182
There is practically no alternative/competitor to __________ in the beneficiation treatment of sulphide ores.
froth floatation
183
Separation of isotopes is generally done using a/an __________ centrifuge.
ultra
184
Temperature of the product during ultrafine grinding
increases
185
Reciprocating screens are normally inclined at an angle of 5° with the horizontal and employ gyratory motion at feed end & reciprocating motion at the discharge end. They are not suitable for the screening of the
heavy tonnages of rocks or gravel.
186
In a ball mill, the volume occupied by the balls (when the mill is stopped) is about __________ percent of the volume of the mill.
50
187
Separation of materials of the same density based on their sizes by using then-different rates of flow is called
sizing
188
Molten ammonium nitrate is mixed with ground limestone in fertilizer plant in a
pug mill
189
Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are
silicates & phosphates
190
For a sphere falling in the constant drag co-efficient regime, its terminal velocity depends on its diameter (d) as
d^2
191
With increase in the capacity of screens, the screen effectiveness
decreases
192
As particle size is reduced
screening becomes progressively more difficult.
193
Rittinger number which designates the new surface prduced per unit of mechanical energy absorbed by the material being crushed, depends on the
a. state or manner of application of the crushing force.
b. ultimate strength of the material.
c. elastic constant of the material.
d. all (a), (b) and (c).
all (a), (b) and (c).
194
Dust collection efficiency of electrostatic precipitator can be as high as 99.9%. Maximum temperature and pressure of dust laden gas that can be cleaned in an electrostatic precipitator is respectively.
1000°C and 10 atm.
195
For efficient grinding, ball mills must be operated
at a speed less than the critical speed.
196
In a size reduction crushing operation, the feed size is 10 to 50 mm, while the product size is 2 to 10 mm. This is a case of __________ crushing.
fine
197
For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter)
π(=A/D2)
198
The reduction ratio for grinders is defined as(where, Df and Dp are average diameters of feed and product respectively).
Df/Dp
199
Pick out the wrong statement pertaining to the turbine agitator.
a. Recommended peripheral speed for the turbine agitator is 200-250 metres/minute.
b. Pitched blade turbine agitator gives only radial flow with complete absence of the axial flow.
c. Generally, the diameter of the agitator is kept between l/3rd to l/6th of the tank diameter while the blade length is l/4th of agitator diameter (with central disc, it is l/8th of the agitator diameter).
d. Turbine agitator should be located at a height not less than one agitator diameter length from the bottom. If the depth of liquid in the tank is more than twice the agitator diameter, two agitators should be used.
Pitched blade turbine agitator gives only radial flow with complete absence of the axial flow.
200
A fluid energy mill is used for
ultra grinding
201
Which of the following is the softest material ?
a. Talc
b. Feldspar
c. Corundum
d. Calcite
Talc
202
Dry powdery solid materials are transported by a __________ conveyor.
screw
203
Fluid energy mill comes in the category of
ultrafine grinder
204
For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid
Kozney-Karman equation
205
Which of the following is a continuous filter?
a. Plate and frame filter
b. Cartridge filter
c. Shell and leaf filter
d. None of these
None of these
206
During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration
at the end of filtration.
207
In screen analysis, the notation +5 mm/-10 mm means particles passing through
10 mm screen and retained on 5 mm screen.
208
Optimum ratio of operating speed to critical speed of a trommel is
0.33-0.45
209
The process opposite to 'dispersion' is termed as the
flocculation
210
Grinding efficiency of a ball mill is of the order of __________ percent
1 - 5
211
Solid particles of different densities are separated by
sorting classifier
212
During agitation of liquids, power consumption during laminar flow is not proportional to the
density of the liquid
213
Trommels are revolving screens which normally operate in the range of __________ rpm
15 - 20
214
The value of work index does not change materially from one equipment to another. If the value of work index determined for close circuit grinding is Wi, then the same for open circuit grinding will be
1.34 Wi
215
Maximum size reduction in a fluid energy mill is achieved by
interparticle attritio
216
Filtration rate through a filter cake is proportional to (where, S = filtering surface R= specific cake resistance μ = viscosity of the filtrate)
a. S
b. 1/R
c. 1/μ
d. all (a), (b) & (c)
all (a), (b) & (c)
217
A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is
1-2 w^2 . δρL (2R + δ)
218
Which one is a filter aid ?
a. Convas fabric
b. Diatomaceous earth
c. Calcined lime
d. None of these
Diatomaceous earth
219
To remove dirt from the flowing fluid, we use a
strain
220
Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher ?
Gyratory crusher
221
Separation of solid suspended in liquid into a supernatant clear liquid and a denser slurry employs a process termed as the
sedimentation
222
Ultrafine grinders operate principally by
attrition
223
Which of the following comes in the category of primary crusher for hard and tough stone ?
Jaw crusher
224
Crushing efficiency of a machine ranges between __________ percent.
0.1 to 2
225
Screen capacity is expressed in terms of
tons/hr-ft
226
A screen is said to be blinded, when the
screen is plugged with solid particles.
227
What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls
0.66
228
Percentage of drum submerged in the slurry in case of rotary drum filter is
30
229
Filter medium resistance is that offered by the
filter cloth and the embedded particle collectively.
230
In a roll crusher, both the rolls
a. have the same diameter.
b. are rotated towards each other.
c. run either at the same or different speeds.
d. all (a), (b) and (c).
all (a), (b) and (c).
231
Tube mill compared to ball mill
a. produces finer products.
b. is long in comparison with its diameter.
c. uses smaller balls.
d. all (a), (b) & (c).
all (a), (b) & (c).
232
For the preliminary breaking of hard rock, we use a
gyratory crusher
233
Filtration operation carried out by continuous increase of the inlet pressure of slurry, is called the __________ filtration.
constant rate
234
Pick out the wrong statement.
a. For the compressible cake, voidage & the specific resistance of the cake can be assumed to be constant.
b. Cake resistance is independent of the pressure drop.
c. Crushing of explosive materials are done by employing drygrinding.
d. Gyratory crusher is a coarse crusher.
Cake resistance is independent of the pressure drop.
235
Which of the following oxides is not present in hematite iron ore?
a. Titanium oxide
b. Calcium oxide
c. Cobalt oxide
d. Manganese oxide
Cobalt oxide
236
Ribbon blenders are exclusively meant for
non-flowing powder and thin pastes.
237
In closed circuit grinding as compared to open circuit grinding, the
operation is economical.
238
Pick out the correct statement
a. Angle of repose is always greater than the angle of slide.
b. A hopper is a small bin with a sloping bottom.
c. A silo is a short height vessel of very large diameter used for the storage of high volatile matter coal.
d. Pine oil is used as a 'modifying agent' (for activating or depressing the adsorption of filming agents) in froth floatation process.
A hopper is a small bin with a sloping bottom
239
Gelatinous solid (which plug the septum) can be filtered by a __________ filter.
precoat
240
During the washing of cak
all the resistances are constant.
241
The opening of a 200 mesh screen (Taylor series) i
0.0074 cm
242
A gravity decanter is meant for the separation of two __________ density.
immiscible liquids of different
243
The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the __________ filter.
sand
244
Separation of solid particles based on their densities is called
sorting
245
Activators are those chemicals which help buoying up one mineral in preference to the other in the froth floatation process. Which of the following is an activator?
Copper sulphate
246
__________ are mixed using ribbon blenders.
Dry powders
247
During agitation of liquids, the
a. Froude number is independent for the curves between power number and Reynolds number in baffled system.
b. Power number becomes independent of impellers Reynolds number at high Reynolds number, but is dependent on the geometry of the impeller.
c. Froude number is used to account for the effect of surface (e.g., the centre vortex) on the power number.
d. all (a), (b) and (c).
all (a), (b) and (c).
248
For crushing of solids, the Rittinger's law states that the work required for crushing is proportional to
the new surface created.
249
In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing
primary
250
As per Taggart's formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where, L = Length of feed opening, cms S = Maximum width of discharge opening, cms )
93 LS
251
The process by which fine solids is removed from liquids is termed a
sedimentation
252
Which of the following crushing laws is most accurately applicable to the fine grinding of materials ?
Rittinger's law
253
Shell and leaf filter as compared to plate and frame filter
a. entails less labor cost.
b. facilitates filtration under higher pressure.
c. provides more effective washing.
d. all (a), (b) & (c)
all (a), (b) & (c)
254
Metallic wire mesh is used as a filtering medium for the separation of dust from dust laden gas in case of a/an
air filter
255
Which of the following is a coarse crusher?
Gyratory crusher
256
Sorting classifiers employing differential settling methods for separation of particles make use of the differences in their
terminal velocities
257
Separation of particles of various sizes, shapes and densities by allowing them to settle in a fluid is called
classification
258
The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake)
independent of ΔP
259
To produce talcum powder, use
ball mill
260
Angle of nip of the crushing rolls does not depend upon the
speed of the rolls
261
Paddle agitator
is suitable for mixing low viscosity liquids.
262
Pick out the wrong statement.
a. More commonly used jaw crusher between Dodge jaw crusher and Blake jaw crusher is the later one.
b. There are only four methods namely compression, impact, attrition and cutting, which the size reduction equipments employ.
c. Cutting machines mainly employ 'attrition' for size reduction of solids.
d. Operating principles of Dodge and Blake jaw crushers are combined in the working of universal jaw crushers.
Cutting machines mainly employ 'attrition' for size reduction of solids.
263
Gummy & sticky materials like molasses, sugar etc. are best transported/handled by using a __________ conveyor.
ribbon
264
Soft & non-abrasive materials can be made into fines by
attrition
265
The critical speed of a trommel (N) is related to its dia (D) as
N ∝ sqrt D
266
Which of the following minerals is not subjected to magnetic separation method?
Galena
267
Which of the following is not a revolving/tumbling mill used for size reduction?
Cage mill
268
Which of the following achieves the least reduction ratio for a given feed size?
Roll crusher
269
A fluid energy mill is used for
ultragrinding
270
For coarse reduction of hard solids, use
compression
271
In a size reduction crushing operation, feed size is 100 to 300 mm. while the product size is 10 to 50 mm. This is a case of the __________ crushing.
secondary
272
Traces of liquid tar fog present in coke oven gas is separated using
electrostatic precipitator
273
Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with __________ to get the same for dry grinding.
1.34
274
Choke crushing (in case of a Jaw crusher) compared to free crushing
consumes more power.
275
The specific surface of sherical particles is proportional to (where, Dp = diameter of particle).
1/Dp
276
Wheat is ground into flour in a
roller crusher
277
Gravity stamp mill is meant for the __________ crushing.
fine
278
Washability curve based on float and sink test enables an assessment to be made of the possibility of cleaning a coal fraction based on the
density separation.
279
Pick out the wrong statement:
a. Magnetic separation method can be employed to treat both dry & wet ores.
b. Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size.
c. Gyratory crusher is used for coarse crushing.
d. Screens are of stationary, moving and vibratory types.
Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size.
280
To get ultrafine particles, the equipment used is a
fluid energy mill
281
Vacuum filter is most suitable for the
a. removal of fines from liquid.
b. liquids having high vapour pressure.
c. liquids of very high viscosity.
d. none of these.
none of these.
282
The porosity of a compressible cake is
minimum at the filter medium.
283
Which of the following conveyors cannot be recommended for transportation of abrasive materials ?
Flight conveyor
284
Separation of materials into products based on the difference of their sizes is called
sizing
285
For classification of potable (drinking) water, we use a __________ filter.
gravity sand
286
Hot, lumpy & abrasive materials are best transported by using a/an __________ conveyor.
apron
287
In case of grinding in a ball mill
a. wet grinding achieves a finer product size than dry grinding.
b. its capacity decreases with increasing fineness of the products.
c. grinding cost and power requirement increases with increasing fineness of the products.
d. all (a), (b) and (c).
all (a), (b) and (c).
288
The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area, m2 V = rising velocity of fluid, m/sec.S = percentage of solids in the suspension by volume.ρ = density of solids, kg/m3)
3.6 AVS.ρ
289
Kick's law relates to
energy consumption
290
__________ mill is normally used for grinding of talc.
Ring-roll
291
Colloidal mills are used for __________ grinding.
ultrafine
292
The maximum slope of a belt conveyor can be
30°
293
The filter medium resistance is controlled by
both pressure drop and flow rate
294
The unit of filter medium resistance is
cm-1
295
During size reduction by a jaw crusher, the energy consumed decreases with the
increasing size of feed at constant reduction ratio.
296
Which of the following can be most effectively used for clarification of lube oil and printing ink?
Sharpies supercentrifuge
297
Ultracentrifuges running at speeds upto 100000 rpm is normally used for the
separation of isotopes based on their density or molecular weights difference.
298
Sizing of very fine particles of the order of 5 to 10 microns is done by elutriation, which is a __________ operation.
classification
299
Size reduction of fibrous materials like wood, asbestos, mica etc. is done by a disintegrator exemplified by the
cage mill
300
The material is crushed in a gyratory crusher by the action of
compression
301
The equivalent diameter of channel of a constant non-circular cross-section of 3 cm by 6 cm will be __________ cms.
2
302
Which of the following may prove unsuitable for filtering volatile liquids ?
Vacuum filter
303
__________ mean diameter of particles is given by
volume
304
Mass flow of granular solid (M) through a circular opening of dia, D follows
M ∝ D3
305
Sauter mean diameter is the same as the __________ mean diameter.
volume-surface
306
Cake resistance is
a. important in the beginning of filtration.
b. decreased with the time of filtration.
c. independent of pressure drop.
d. none of these.
none of these.
307
In paint industries, blending of light paste is done by using a
charge can mixer
308
A sand mixture was screened through a standard 10-mesh screen. The mass fraction of the oversize material in feed, overflow and underflow were found to be 0.38, 0.79 and 0.22 respectively. The screen effectiveness based on the oversize is
0.5
309
__________ is used for producing a thick suspension from a thin slurry.
Pressure filter thickener
310
Wet seiving is employed, when the product contains __________ materials.
large quantity of very fine
311
Energy requirement (per unit mass of material crushed/ground) is highest for
fluid energy mill
312
The energy consumed by a ball mill depends on
a. its speed.
b. its ball load.
c. the density of the material being ground.
d. all (a), (b) and (c).
all (a), (b) and (c).
313
Energy consumption in a crusher decreases with increase in the
a. size of the product (at constant feed size).
b. capacity of the crushing machine.
c. size of feed (at constant reduction ratio).
d. all (a), (b) & (c).
all (a), (b) & (c).
314
In a mixer, the quantity, (v. L/D) is termed as __________ number(where, v = longitudinal velocity of material, L = length of the mixer, D = diffusivity in axial mixing).
Peclet
315
The term 'angle of nip' is concerned with the operation of the __________ crushers.
roll
316
Cartridge filters are termed as 'edge' filters, because of the fact that the
bulk of the solids are removed at the periphery of the disks.
317
Vibrating screens have capacity in the range of __________ tons/ft2 .mm mesh size.
0.2 to 0.8
318
Cumulative analysis for determining surface is more precise than differential analysis, because of the
assumption that all particles in a single fraction are equal in size, is not needed.
319
To remove very small amount of tiny solid impurities from liquid, we use a
coagulant
320
Screw conveyors are
suitable for sticky materials.
321
__________ mills fall in the category of tumbling mills,
a. Ball and pebble
b. Rod and tube
c. Compartment
d. all (a), (b) & (c)
all (a), (b) & (c)
322
Capacity of flight conveyor in tons/hr is given by (where, W & D = width and depth of flight respectively in metre V = speed of the conveyor, metre/second ρ = bulk density of material, kg/m3)
3.6 W.D.V.ρ
323
Which of the following is not a cutting machine?
a. Dicers
b. Knife cutters
c. Slitters
d. Tube mills
Tube mills
324
Weber number is significant and is concerned with the
dispersion of liquid in liquid.
325
Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid.
density
326
Screen efficiency is
a. recovery/rejection
b. recovery
c. rejection
d. none of these
none of these
327
For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a
Buhrstone mill
328
Handling of ashes and similar materials can be done best by a __________ conveyor.
drag or slat
329
Which of the following must be stored in silos and not in open yard ?
High V.M. bituminous coal
330
Apron conveyors are used for
heavy loads & short runs.
331
Sedimentation on commercial scale occurs in
rotary drum filters
332
With increase in drum speed, in a rotary drum filter, the filtration rate
increases
333
Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them.
a. Jaw crusher, Ball mill, Fluid energy mill
b. Ball mill, Jaw crusher, Fluid energy mill
c. Fluid energy mill, Jaw crusher, Ball mill
d. Fluid energy mill, Ball mill, Jaw crusher
Jaw crusher, Ball mill, Fluid energy mill
334
200 mesh seive size corresponds to __________ microns.
74
335
What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls ?
32°
336
For a turbine agitated and baffled tank, operating at low Reynold's number (based on impeller diameter), the power number (Np) varies with NRe as
Np ∝ 1/NRe
337
Which of the following is not accomplished by agitation of liquids in agitators?
a. Dispersing gas in liquid.
b. Blending of immiscible liquids.
c. Dispersing immiscible liquid in form of emulsion.
d. Suspending solid particles.
Blending of immiscible liquids.
338
Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation ?
a. Check plates
b. Jaw plates
c. Toggles
d. Crush shaft
Jaw plates
339
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
340
In froth floatation, chemical agent added to cause air adherence is called
collector
341
The sphericity of a solid particle of cubical shape is
(π/6)^1/3
342
A cottrel precipitator makes use of the __________ for dusty air cleaning.
corrona discharge
343
If radius of a batch basket centrifuge is halved & the r.p.m. is doubled, then the
centrifugal force is doubled.
344
The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is
a. 1.5
b. 1
c. 2
d. none of these
none of these
345
Compressibility co-efficient for an absolutely compressible cake is
1
346
Mixing of plastic solids is generally facilitated by
kneading
347
Which of the following is not an industrial screening equipment ?
a. Sharpies centrifuge
b. Vibrating screen
c. Grizzly
d. Trommel
Sharpies centrifuge
348
Which of the following is not a wet classifier ?
a. Sharpies supercentrifuge
b. Hydrocyclones
c. Dorr Oliver rake classifier
d. None of these
None of these
349
Helical screw agitator is used for
mixing highly viscous pastes.
350
For raschig rings, the sphericity is
<1
351
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
352
__________ mills are termed as disintegrators.
Cage
353
Supporting legs of a plate and frame filter is normally made of
cast iron
354
Wet grinding in a revolving mill __________ as compared to dry grinding.
increases capacity
355
A compressible cake has the
maximum porosity at the upstream side.
356
Which of the following is not used as a filter medium in case of corrosive liquids ?
a. Nylon
b. Glass cloth
c. Metal cloth of monel or stainless steel
d. Cotton fabric
Cotton fabric
357
In ball mill operation, the feed size (Df in meters) and the ball diameter (Db in 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
358
Pine oil and cresylic acid are used as __________ in the froth floatation process.
frother
359
Grinding characteristic of a material is given by its
HGI
360
Which of the following is not a non-metalliferous mineral?
a. Calcite
b. Fluorspar
c. Quartz
d. Cassiterrite
Cassiterrite
361
Filter medium resistance is important during the __________ of filtration.
early stages.
362
Float and sink test determines the possibility of cleaning of coal by a process based on the
gravity separation
363
__________ baffles are provided in ball mills.
Horizontal
364
Mixer used for rubber compounding is
banbury internal mixer
365
For spheres, the specific surface shape factor is given by
AD/V
366
__________ mill is not used for grinding wheat into flour and for milling of cereals & other vegetable products.
Pebble
367
In case of a hammer crusher, the final product size depends on the
a. feed rate.
b. rotor speed.
c. clearance between hammer & grinding plates.
d. all (a), (b) and (c).
all (a), (b) and (c).
368
Sphericity of raschig ring (whose length and diameter are equal) is
1
369
Mixing mechanism employed in a pan mixer is by
mulling
370
Chance process is used for the
cleaning of coal.
371
Which of the following screens has the maximum capacity ?
a. Grizzlies
b. Trommels
c. Shaking screen
d. Vibrating screen
Vibrating screen
372
Stamp mills are generally used for crushing
gold ores
373
In case of a plate and frame filter press, filtrate flow through the cake follows __________ flow.
laminar
374
Which of the following is a batch sedimentation equipment ?
a. Dust catcher
b. Filter thickener
c. Dry cyclone separator
d. Rotary sprayer scrubber.
Filter thickener
375
The most suitable equipment for the transportation of 200 mesh size particles is a
pneumatic conveyor
376
Which of the following is not used as filter aid?
a. Asbestos
b. Diatomaceous earth
c. Purified wood cellulose
d. Rice husk
Rice husk
377
Raw materials are charged in the iron blast furnace using
skip hoist
378
Carbon black is pulverised in a
ball mill
379
The most efficient equipment for the removal of sub-micronic dust particles from blast furnace gas is the
electro-static precipitator
380
The filtrate flow rate in constant pressure filtration
continuously decreases.
381
Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripherial velocity, m/sec. W = width of rolls, m Dr = distance between rolls ρ = density of material to be crushed, kg/m3 here, V =πN.D where, N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m)
3.6 V.W.Dr.ρ
382
Vibrating screens are used for handling large tonnages of materials. The vibrating motion is imparted to the screening surface by means of
a. electromagnets
b. cams or eccentric shafts
c. unblanced fly wheels
d. either (a), (b) or (c).
d. either (a), (b) or (c).
383
The inlet pressure in a constant rate filtration
increases continuously
384
Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is __________ microns.
< 74
385
__________ centrifuge is the most suitable for separation of non-friable crystals.
Perforated horizontal basket continuous
386
For benefication of iron ore, the most commonly used method is
jigging & tabling.
387
A propeller agitator
produces mainly axial flow.
388
Screen capacity is proportional to (where, S = screen aperture)
S
389
In coal washeries, three products namely the valuable product (i.e. clean/washed coal), discarded product (i.e. mineral matter) and an additional concentrated product called __________ is produced.
middling
390
Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed ?
Dry grindng of large particles in un-baffed mills.
391
A __________ employs a set of screen across a flow channel for the separation of dirt/rust from a flowing liquid stream.
strainer
392
Separation of a suspension or slurry into a supernatant clear liquid (free from particles) and a thick sludge containing a high concentration of solid is called
sedimentation
393
Reciprocal of sphericity is termed as the
shape factor
394
With increase in the pressure drop across the cake, the specific cake resistance for the compressible sludge
increases
395
Pick out the wrong statement.
a. Hammer crushers operate by impact action.
b. Standard screens have circular opening.
c. With increase in mesh number of screens, their diameter in microns decreases.
d. 200 mesh screen has 200 openings per linear cm.
200 mesh screen has 200 openings per linear cm
396
Size reduction of ice and gypsum can be accomplished suitably by a __________ crusher.
toothed roll
397
A filter press is
a batch filter.
398
Xanthates are used in the froth floatation process as a/an
collector
399
The ratio of the actual mesh dimension of Taylor series to that of the next smaller screen is
sqrt(2)
400
Limestone is normally crushed in a
hammer crusher
401
Filtrate flow rate in case of a rotary drum vacuum filter (in which Rm < < Rc) is proportional to __________ and the cycle time (where, μ = filtrate viscosity Rm = filter medium resistance Rc = cake resistance ).
1/sqrt(μ)
402
The main differentiation factor between tube mill and ball mill is the
length to diameter ratio.
403
Introduction of slurry in a plate and frame filter press is done through a plate in each frame. The plate of this filter has a __________ surface.
ribbed
404
A belt conveyor used for the transportation of materials can
a. run upto 1 km.
b. travel at a speed upto 300 metres/minute.
c. handle materials upto 5000 tons/hr.
d. all (a), (b) and (c).
d. all (a), (b) and (c).
405
Which of the following is not used as a surface active agent in a flocculation operation?
a. Sodium silicate
b. Quartz
c. Lime
d. Alumina
Quartz
406
__________ mill is not a revolving mill.
a. Pebble
b. Compartment
c. Cage
d. Tube
Cage
407
For the transportation of ultrafine particles, the equipment used is a........conveyor.
pneumatic
408
During filtration operation, the filtrate encounters the resistance of the
a. filter medium.
b. cake.
c. channel carrying the slurry to the upstream side of the cake and filtrate away from the filter medium.
d. all (a), (b) and (c)
all (a), (b) and (c)
409
Filtration rate does not depend upon the
a. pressure drop & area of filtering surface.
b. resistance of the cake & the septum.
c. properties of the cake & the filtrate.
d. none of these.
none of these.
410
Which of the following is a fine crusher?
a. Blake jaw crusher
b. Gyratory crusher
c. Toothed roll crusher
d.Dodge jaw crusher
Toothed roll crusher
411
__________ is a cohesive solid.
Wet clay
412
The optimum moisture content in solids to be crushed/ground ranges from __________ percent.
3 to 4
413
The capacity of a gyratory crusher is __________ that of a jaw crusher with the same gape, handling the same feed & for the same product size range.
2.5 times
414
Dispersion of a gas through liquid is done by using a
sparger
415
Work index is defined as the
gross energy (kWh/ton of feed) needed to reduce very large feed to such a size that 80% of the product passes through a 100 micron screen.
416
Removal of activated carbon from glycerine is done by
plate and frame filter
