(5) Mechanical Operations Flashcards
1
Q
Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a __________ conveyor.
A
2
Q
Equivalent diameter of a particle is the diameter of the sphere having the same
A
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
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4
Q
Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill )
A
5
Q
Pick out the wrong statement.
A
6
Q
In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the
A
7
Q
For sizing of fine materials, the most suitable equipment is a
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8
Q
Which of the following is not categorised as a “mechanical operation” ?
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9
Q
Which of the following is a pressure filter?
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10
Q
Tabular bowl centrifuges as compared to disk bowl centrifuges
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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
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
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
14
Q
Pick out the wrong statement pertaining to the roll crushers.
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15
Q
Which of the following is not an ultrafine grinder (colloid mill)?
A
16
Q
Two particles are called to be equal settling, if they are having the same.
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17
Q
Which of the following is the most suitable for handling fibrous and dense slurries?
A
18
Q
__________ centrifuge is normally used in sugar mills.
A
19
Q
Solid particles separation based on the difference in their flow velocities through fluids is termed as the
A
20
Q
Diatomaceous earth is a/an
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21
Q
The distribution given by microscopic analysis of powder is
A
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)
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23
Q
For a non-spherical particle, the sphericity
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24
Q
In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is
A
25
Ball mills and tube mills with flint or porcelain balls are used for size reduction of
26
Size reduction of __________ is accomplished in steam heated rollers and roll crushers.
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.
28
Which of the following is not a part of the Blake jaw crusher?
29
If a force greater than that of gravity is used to separate solids & fluids of different densities, the process is termed as the
30
Filter aid is used to
31
Which of the following mineral dressing operations is termed as 'comminution'?
32
The capacity of a pneumatic conveying system depends upon the
33
Pick out the wrong statement.
34
Gravity settling process is not involved in the working of a
35
Froth floatation is the most suitable for treating
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
37
Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm)?
38
Pick out the correct statement:
39
Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is
40
Highly viscous liquids & pastes are agitated by
41
The value of 'angle of nip' is generally about
42
Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.
43
Sulphuric acid mist is arrested by using a __________ scrubber.
44
The main size reduction operation in ultrafine grinders is
45
In case of a hammer crusher,
46
Jigging is a technique by which different particles can be
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.
48
Balls for ball mills are never made of
49
200 mesh screen means 200 openings per
50
__________ is the most commonly used 'filter aid'.
51
Energy consumed for crushing one ton of material ranges from __________ kWh.
52
For transporting pasty material, one will use a/an
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
54
A tube mill compared to a ball mill
55
Trommels separate a mixture of particles depending on their
56
Basic slag is not ground in
57
Grindability of a material does not depend upon its
58
Shape factor for a cylinder whose length equals its diameter is
59
In case of a hammer crusher, the
60
Dust laden air can be purified using a
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
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)
63
Vacuum is applied in __________ zone, in case of a general type continuous rotary drum vacuum filter.
64
General crushing equation is given by https://www.indiabix.com/_files/images/chemical-engineering/mechanical-operations/122-368-1.png . Bond's crushing law isobtained by solving this equation for n = __________ and feed of infinite size.
65
Which of the follwoing mechanical conveyors does not come under the division 'scrapers' ?
66
__________ mixer is used for devulcanisation of rubber scrap & making water dispersion & rubber solution.
67
Which of the following mechanical conveyors does not come under the division 'carriers'?
68
Screen capacity is not a function of
69
Which of the following is a vacuum filter?
70
Pine oil used in froth floatation technique acts as a/an
71
Length/diameter ratio of a ball mill is
72
Feed size of ≥ 25 cms can be accepted by
73
Which is the most suitable conveyor for transportation of sticky material?
74
The most suitable equipment for removing the fine dust particle (< 1 micron dia.) from air below its dew point will be a/an
75
Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is
76
Filtration of water in a paper mill is done by a/an __________ filter.
77
Moore filter is a __________ filter.
78
Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is
79
Ball mill is used for
80
In case of a ball mill,
81
Maximum size reduction in a ball mill is done by the, __________ action.
82
Increasing the capacity of a screen __________ the screen effectiveness.
83
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
84
Bond crushing law
85
Flow of filtrate through the cake in a plate and frame filter press is best described by the __________ equation.
86
The controlling resistance in a rotary drum vacuum filter is the __________ resistance.
87
Which of the following is used for primary crushing of very hard lumpy materials?
88
Coal is finally pulverised to 200 mesh size for burning in boilers by a
89
Crushing efficiency is the ratio of the
90
The resistance offered by the filter used in a bag filter is proportional to (where, c = dust concentration, and s = particle size )
91
Cement clinker is reduced to fine size by a
92
The crushed material received for separation is called feed or
93
For spheres, volume shape factor is given by
94
Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids ( > 50000 centipoise)?
95
__________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals.
96
The operating speed of a ball mill should be __________ the critical speed.
97
Use of baffles in agitators help in minimising the __________ tendency.
98
__________ are used for the separation of coarse particles from a slurry of fine particles.
99
Fibrous material is broken by a
100
__________ is the most suitable for compounding rubber and plastic solids.
101
Out of the following size reduction equipments, the maximum feed size can be accepted by the
102
Bucket elevators are not suitable for the vertical lifting of __________ materials.
103
The most common filter aid is
104
For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the __________ filter.
105
For separation of sugar solution from settled out mud, we use a __________ filter.
106
The sphericity of a cylinder of 1 mm diameter and length 3 mm is
107
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.
108
What is the selectivity index, if the grade of tailings & concentrate is the same?
109
The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a
110
Traces of solids are removed from, liquid in a
111
_________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.
112
The speed of a rotary drum vacuum filter may be about __________ rpm.
113
Colloid mills achieve size reduction mainly by
114
Mesh indicates the number of holes per
115
For achieving maximum capacity of the ball mill, the ball charge should be equal to about __________ percent of the ball mill volume.
116
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).
117
Which of the following gives the work required for size reduction of coal to -200 mesh in a ball mill most accurately ?
118
Electrical energy consumed by a jaw crusher is not a function of the
119
Size reduction mechanism used in Jaw crushers is
120
Trommels employ __________ for screening of materials.
121
A widely used size reduction equipment for __________ is Bradford breaker.
122
Ultra centrifuges are used for the separation of __________ solid particles.
123
Specific surface area is the surface area of a unit __________ of materials.
124
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.
125
The constants (Kb, Kr and Kk) used in the laws of crushing (i.e., Bond's law, Rittinger's law and Kick's law) depend upon the
126
Size reduction does not occur due to compression in case of
127
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
128
Which of the following represents the plot of filtrate volume versus time for constant pressure filtration?
129
Driving force in case of filtration by a centrifuge is the
130
Rod mills employed for grinding
131
Production rate __________ with increased fineness, with a given energy input to the size reduction machine.
132
Gold ore concentration is mostly done using
133
Mixing of light fine powder such as insecticides is done by
134
Run of mine (ROM) coal is crushed by a __________ for use in domestic ovens.
135
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?
136
The unit of specific cake resistance is
137
Size reduction of asbestos and mica is done by
138
A pebble mill
139
The study on washability of coal is done by using the __________ technique.
140
Horsepower required for a roll crusher is directly proportional to its
141
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
142
__________ conveyor is the most suitable for long distance transportation of cold, non-abrasive granular/irregular shape/fine materials.
143
The specific cake resistance for compressible sludges is a function of the pressure drop
144
Moisture can be removed from lubricating oil using
145
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
146
Pick out the wrong statement.
147
Addition of filter aid to the slurry before filtration is done to ...... of the cake.
148
Which of the following terminology is not used for size reduction of materials to fine sizes or powders?
149
A tube mill as compared to a ball mill
150
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
151
Which of the following gives the crushing energy required to create new surface?
152
In filtration, the use of 'filter aid' helps in
153
Critical Speed (Nc) of a ball mill is given by(where R1 andR2 are radii of ball mill and the ball respectively).
154
Gizzlies are used for separating __________ solids.
155
Which of the following clay mixing devices is vacuum operated for deairation of clay?
156
Pick out the material having minimum Rittinger's number.
157
__________ mills are termed as impactors.
158
In case of a revolving mill, wet grinding compared to dry grinding
159
To get a fine talc powder from its granules, the equipment used is
160
For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is
161
Width and speed of a conveyor belt depends upon the __________ of the material.
162
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
163
Pick out the wrong statement.
164
Which of the following size reduction equipments employs mainly attrition for ultrafine grinding?
165
Tank filter (e.g., Nutsch filter) is
166
In bag filters, filter fabrics are never made of
167
Use of 'grinding aids' is done in __________ grinding.
168
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)
169
Which of the following is the most suitable filter for separation of abrasive solids suspended in a corrosive liquid?
170
All resistances during washing of cake
171
A __________ mixer resembles a ball mill without balls.
172
__________ conveyor is the most suitable for short distance transportation of non-abrasive loose materials like garbage, grain, food wastes etc.
173
As the product becomes finer, the energy required for grinding
174
Gyratory crushers compared to the reciprocating jaw crushers
175
The important dimensional group involved in the power requirement calculation in mixing operation is the __________ number.
176
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.
177
Which of the following grinding mills has the horizontally arranged rods as the grinding elements thereby delivering more uniform granular products with minimum fines?
178
Rittinger's crushing law states that
179
Mechanical conveyors which push the material along an endless trough or tube are called scrappers. Which of the following conveying equipments comes under the category of 'scrappers'?
180
Sphericity of pulverised coal is
181
The reduction ratio for fine grinders is
182
Which of the following is the hardest material?
183
General mechanism of size reduction in intermediate and fine grinder is by
184
A straight line is obtained on plotting reciprocal of filtration rate vs. the volume of filtrate for __________ flow of filtrate.
185
The work index in Bond's law for crushing of solids has the following dimensions
186
Ore concentration by jigging is based on the difference in the __________ of the particles.
187
Size measurement of ultrafine particles can be best expressed in terms of
188
Reduction ratio of crushers is the
189
Which is a secondary crusher for a hard & tough stone?
190
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.)
191
Cyclones are used primarily for separating
192
There is practically no alternative/competitor to __________ in the beneficiation treatment of sulphide ores.
193
Separation of isotopes is generally done using a/an __________ centrifuge.
194
Temperature of the product during ultrafine grinding
195
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
196
In a ball mill, the volume occupied by the balls (when the mill is stopped) is about __________ percent of the volume of the mill.
197
Separation of materials of the same density based on their sizes by using then-different rates of flow is called
198
Molten ammonium nitrate is mixed with ground limestone in fertilizer plant in a
199
Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are
200
For a sphere falling in the constant drag co-efficient regime, its terminal velocity depends on its diameter (d) as
201
With increase in the capacity of screens, the screen effectiveness
202
As particle size is reduced
203
Rittinger number which designates the new surface prduced per unit of mechanical energy absorbed by the material being crushed, depends on the
204
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.
205
For efficient grinding, ball mills must be operated
206
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.
207
For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter)
208
The reduction ratio for grinders is defined as(where, Df and Dp are average diameters of feed and product respectively).
209
Pick out the wrong statement pertaining to the turbine agitator.
210
A fluid energy mill is used for
211
Which of the following is the softest material ?
212
Dry powdery solid materials are transported by a __________ conveyor.
213
Fluid energy mill comes in the category of
214
Filtration capacity of a rotary drum vacuum filter depends upon the
215
About 2-3 hp, power per gallon of a thin liquid provides vigrous agitation in an agitator. 'Power number' in agitation is given by
216
__________ conveyors are also called scrapers.
217
For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid
218
Which of the following is a continuous filter?
219
During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration
220
In screen analysis, the notation +5 mm/-10 mm means particles passing through
221
rpm of a trommel at critical speed is given by (where, D = Diameter of trommel in ft)
222
Optimum ratio of operating speed to critical speed of a trommel is
223
The process opposite to 'dispersion' is termed as the
224
The cake resistance increases steadily with the time of filtration in a plate and frame filter employing constant __________ filtration.
225
Grinding efficiency of a ball mill is of the order of __________ percent
226
Solid particles of different densities are separated by
227
During agitation of liquids, power consumption during laminar flow is not proportional to the
228
Trommels are revolving screens which normally operate in the range of __________ rpm
229
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
230
Maximum size reduction in a fluid energy mill is achieved by
231
Filtration rate through a filter cake is proportional to (where, S = filtering surface R= specific cake resistance μ = viscosity of the filtrate)
232
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
233
Which one is a filter aid ?
234
To remove dirt from the flowing fluid, we use a
235
Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher ?
236
Separation of solid suspended in liquid into a supernatant clear liquid and a denser slurry employs a process termed as the
237
Ultrafine grinders operate principally by
238
Half the angle of nip, (α), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively).
239
Which of the following comes in the category of primary crusher for hard and tough stone ?
240
Crushing efficiency of a machine ranges between __________ percent.
241
Screen capacity is expressed in terms of
242
A screen is said to be blinded, when the
243
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
244
Percentage of drum submerged in the slurry in case of rotary drum filter is
245
Filter medium resistance is that offered by the
246
In a roll crusher, both the rolls
247
Tube mill compared to ball mill
248
Critical speed of rotation, N (in rps - rotation per second) of a trammel is equal to (where, g = acceleration due to gravity = 9.81 m/sec2 and, r = radius of trammel, metre. )
249
For the preliminary breaking of hard rock, we use a
250
Filtration operation carried out by continuous increase of the inlet pressure of slurry, is called the __________ filtration.
251
Pick out the wrong statement.
252
Which of the following oxides is not present in hematite iron ore?
253
Ribbon blenders are exclusively meant for
254
In closed circuit grinding as compared to open circuit grinding, the
255
Pick out the correct statement
256
Gelatinous solid (which plug the septum) can be filtered by a __________ filter.
257
During the washing of cak
258
The opening of a 200 mesh screen (Taylor series) i
259
A gravity decanter is meant for the separation of two __________ density.
260
The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the __________ filter.
261
Separation of solid particles based on their densities is called
262
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?
263
__________ are mixed using ribbon blenders.
264
During agitation of liquids, the
265
For crushing of solids, the Rittinger's law states that the work required for crushing is proportional to
266
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
267
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 )
268
The process by which fine solids is removed from liquids is termed a
269
Which of the following crushing laws is most accurately applicable to the fine grinding of materials ?
270
Shell and leaf filter as compared to plate and frame filter
271
Metallic wire mesh is used as a filtering medium for the separation of dust from dust laden gas in case of a/an
272
Which of the following is a coarse crusher?
273
Sorting classifiers employing differential settling methods for separation of particles make use of the differences in their
274
Separation of particles of various sizes, shapes and densities by allowing them to settle in a fluid is called
275
The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake)
276
To produce talcum powder, use
277
Angle of nip of the crushing rolls does not depend upon the
278
Paddle agitator
279
Pick out the wrong statement.
280
Gummy & sticky materials like molasses, sugar etc. are best transported/handled by using a __________ conveyor.
281
Soft & non-abrasive materials can be made into fines by
282
In constant pressure filtration,
283
The critical speed of a trommel (N) is related to its dia (D) as
284
Which of the following minerals is not subjected to magnetic separation method?
285
Which of the following is not a revolving/tumbling mill used for size reduction?
286
Which of the following achieves the least reduction ratio for a given feed size?
287
A fluid energy mill is used for
288
Filtration should be stopped in a filter press, if the
289
For coarse reduction of hard solids, use
290
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.
291
Traces of liquid tar fog present in coke oven gas is separated using
292
Close circuit grinding by a ball mill with air sweeping employs a
293
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.
294
Choke crushing (in case of a Jaw crusher) compared to free crushing
295
The specific surface of sherical particles is proportional to (where, Dp = diameter of particle).
296
Wheat is ground into flour in a
297
Gravity stamp mill is meant for the __________ crushing.
298
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
299
Toothed roll crushers achieve size reduction by
300
Pick out the wrong statement:
301
To get ultrafine particles, the equipment used is a
302
Vacuum filter is most suitable for the
303
The porosity of a compressible cake is
304
Which of the following conveyors cannot be recommended for transportation of abrasive materials ?
305
Separation of materials into products based on the difference of their sizes is called
306
For classification of potable (drinking) water, we use a __________ filter.
307
Hot, lumpy & abrasive materials are best transported by using a/an __________ conveyor.
308
Additives used for promoting the floccula-tion of particles is a/an
309
In case of grinding in a ball mill
310
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)
311
Kick's law relates to
312
__________ mill is normally used for grinding of talc.
313
Colloidal mills are used for __________ grinding.
314
Fluid medium used in the classification technique of mineral beneficiation is
315
The maximum slope of a belt conveyor can be
316
The filter medium resistance is controlled by
317
The unit of filter medium resistance is
318
During size reduction by a jaw crusher, the energy consumed decreases with the
319
Which of the following can be most effectively used for clarification of lube oil and printing ink?
320
Ultracentrifuges running at speeds upto 100000 rpm is normally used for the
321
Sizing of very fine particles of the order of 5 to 10 microns is done by elutriation, which is a __________ operation.
322
In the cyclone separator used for separation of dust from dust laden gas, the gas
323
The basic filtration equation is given as where, https://www.indiabix.com/_files/images/chemical-engineering/mechanical-operations/136-487-1.png V is volume of the filtrate ; A is the filtration area, a is specific cake resistance, μ is viscosity of the filtrate, and Cis the concentration of the solids in the feed slurry.
In a 20 minutes constant rate filtration, 5 m3 of filtrate was obtained. If this is followed by a constant pressure filtration, how much more time in minutes, it will take for another 5 m3 of filtrate to be produced ? Neglect filter medium resistance, Rm ; assume incompressible cake.
324
Size reduction of fibrous materials like wood, asbestos, mica etc. is done by a disintegrator exemplified by the
325
The material is crushed in a gyratory crusher by the action of
326
The equivalent diameter of channel of a constant non-circular cross-section of 3 cm by 6 cm will be __________ cms.
327
Which of the following may prove unsuitable for filtering volatile liquids ?
328
__________ mean diameter of particles is given by
329
Mass flow of granular solid (M) through a circular opening of dia, D follows
330
Sauter mean diameter is the same as the __________ mean diameter.
331
Cake resistance is
332
In paint industries, blending of light paste is done by using a
333
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
334
__________ is used for producing a thick suspension from a thin slurry.
335
Wet seiving is employed, when the product contains __________ materials.
336
Energy requirement (per unit mass of material crushed/ground) is highest for
337
The energy consumed by a ball mill depends on
338
Energy consumption in a crusher decreases with increase in the
339
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).
340
The term 'angle of nip' is concerned with the operation of the __________ crushers.
341
Cartridge filters are termed as 'edge' filters, because of the fact that the
342
Vibrating screens have capacity in the range of __________ tons/ft2 .mm mesh size.
343
Cumulative analysis for determining surface is more precise than differential analysis, because of the
344
To remove very small amount of tiny solid impurities from liquid, we use a
345
Screw conveyors are
346
__________ mills fall in the category of tumbling mills,
347
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)
348
Which of the following is not a cutting machine?
349
Weber number is significant and is concerned with the
350
Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid.
351
Screen efficiency is
352
For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a
353
Handling of ashes and similar materials can be done best by a __________ conveyor.
354
Which of the following must be stored in silos and not in open yard ?
355
Apron conveyors are used for
356
Sedimentation on commercial scale occurs in
357
With increase in drum speed, in a rotary drum filter, the filtration rate
358
Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them.
359
200 mesh seive size corresponds to __________ microns.
360
What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls ?
361
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
362
Which of the following is not accomplished by agitation of liquids in agitators?
363
Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation ?
364
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
365
The specific surface of spherical particles is given by (where D and ρ are diameter and density of particle).
366
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)
367
In froth floatation, chemical agent added to cause air adherence is called
368
The sphericity of a solid particle of cubical shape is
369
Vertical transportation of materials can be done by a/an
370
In a roll crusher, the specific power consumption and the production rate is affected by the
371
A cottrel precipitator makes use of the __________ for dusty air cleaning.
372
Pick out the correct statement.
373
If radius of a batch basket centrifuge is halved & the r.p.m. is doubled, then the
374
The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is
375
Compressibility co-efficient for an absolutely compressible cake is
376
Mixing of plastic solids is generally facilitated by
377
grinding element & the housing.
378
Which of the following is not an industrial screening equipment ?
379
Which of the following is not a wet classifier ?
380
Helical screw agitator is used for
381
For raschig rings, the sphericity is
382
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.
383
__________ mills are termed as disintegrators.
384
Supporting legs of a plate and frame filter is normally made of
385
The cummulative mass fraction of particles smaller than size dj for a collection of Ni particles of diameter di and mass mi (i = 1, 2, 3, ...... ∞) is given by
386
Wet grinding in a revolving mill __________ as compared to dry grinding.
387
The grinding in a hammer crusher takes place due to the
388
A compressible cake has the
389
Which of the following is not used as a filter medium in case of corrosive liquids ?
390
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))
391
Pine oil and cresylic acid are used as __________ in the froth floatation process.
392
Grinding characteristic of a material is given by its
393
Which of the following is not a non-metalliferous mineral?
394
Filter medium resistance is important during the __________ of filtration.
395
Float and sink test determines the possibility of cleaning of coal by a process based on the
396
__________ baffles are provided in ball mills.
397
Mixer used for rubber compounding is
398
For spheres, the specific surface shape factor is given by
399
__________ mill is not used for grinding wheat into flour and for milling of cereals & other vegetable products.
400
In case of a hammer crusher, the final product size depends on the
401
Sphericity of raschig ring (whose length and diameter are equal) is
402
Mixing mechanism employed in a pan mixer is by
403
Chance process is used for the
404
Which of the following screens has the maximum capacity ?
405
Stamp mills are generally used for crushing
406
In case of a plate and frame filter press, filtrate flow through the cake follows __________ flow.
407
Which of the following is a batch sedimentation equipment ?
408
The most suitable equipment for the transportation of 200 mesh size particles is a
409
Which of the following is not used as filter aid?
410
Raw materials are charged in the iron blast furnace using
411
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
412
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
413
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 ?
414
Pick out the wrong statement pertaining to the roll crushers.
415
Which of the following is not an ultrafine grinder (colloid mill)?
416
Two particles are called to be equal settling, if they are having the same.
417
Which of the following is the most suitable for handling fibrous and dense slurries ?
418
__________ centrifuge is normally used in sugar mills.
419
Solid particles separation based on the difference in their flow velocities through fluids is termed as the
420
Diatomaceous earth is a/an
421
The distribution given by microscopic analysis of powder is
422
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)
423
For a non-spherical particle, the sphericity
424
In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is
425
Ball mills and tube mills with flint or porcelain balls are used for size reduction of
426
Size reduction of __________ is accomplished in steam heated rollers and roll crushers.
427
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.
428
Which of the following is not a part of the Blake jaw crusher?
429
If a force greater than that of gravity is used to separate solids & fluids of different densities, the process is termed as the
430
Filter aid is used to
431
Which of the following mineral dressing operations is termed as 'comminution'?
432
The capacity of a pneumatic conveying system depends upon the
433
Pick out the wrong statement.
434
Gravity settling process is not involved in the working of a
435
Froth floatation is the most suitable for treating
436
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
437
Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm) ?
438
Pick out the correct statement:
439
Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is
440
Highly viscous liquids & pastes are agitated by
441
The value of 'angle of nip' is generally about
442
Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.
443
Sulphuric acid mist is arrested by using a __________ scrubber
444
The main size reduction operation in ultrafine grinders is
445
In case of a hammer crusher,
446
Jigging is a technique by which different particles can be
447
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.
448
Balls for ball mills are never made of
449
200 mesh screen means 200 openings per
450
__________ is the most commonly used 'filter aid'.
