Mechanical Operations Flashcards
Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a __________ conveyor.
screw
Equivalent diameter of a particle is the diameter of the sphere having the same
ratio of surface to volume as the actual volume.
Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill )
D2.5
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
Φs = 6 Vp/dp sp
Pick out the wrong statement.
Size enlargement (opposite of size reduction) is not a mechanical operation.
For sizing of fine materials, the most suitable equipment is a
vibrating screen
In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the
square root of the velocity.
Which of the following is not categorised as a “mechanical operation” ?
Humidification
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
flint or porcelain
Tabular bowl centrifuges as compared to disk bowl centrifuges
operate at higher speed.
Which of the following is a pressure filter ?
Plate and flame filter
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
all ‘a’, ‘b’&’c’
Pick out the wrong statement pertaining to the roll crushers.
Both the rolls run necessarily at the same speed.
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 ?
μ ≥ tan α
Which of the following is not an ultrafine grinder (colloid mill)?
Toothed roll crusher
Two particles are called to be equal settling, if they are having the same.
terminal velocities in the same fluid & in the same field of force.
Which of the following is the most suitable for handling fibrous and dense slurries ?
Cone type agitator
__________ centrifuge is normally used in sugar mills.
Suspended batch basket
Solid particles separation based on the difference in their flow velocities through fluids is termed as the
classification
The distribution given by microscopic analysis of powder is
number
Diatomaceous earth is a/an
filter aid
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)
m/ρ . Vp
For a non-spherical particle, the sphericity
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.
In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is
1/4
Ball mills and tube mills with flint or porcelain balls are used for size reduction of
non-metallic ores
Size reduction of __________ is accomplished in steam heated rollers and roll crushers.
hard rubber
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
Which of the following is not a part of the Blake jaw crusher?
Hanger
If a force greater than that of gravity is used to separate solids & fluids of different densities, the process is termed as the
centrifugation
Which of the following mineral dressing operations is termed as ‘comminution’?
None of these
Filter aid is used to
increase the porosity of the cake
The capacity of a pneumatic conveying system depends upon the
all (a), (b) and (c).
Pick out the wrong statement.
The equipment used for the removal of traces of solids from a liquid is called a classifier.
Gravity settling process is not involved in the working of a
hydrocyclone
Pick out the correct statement:
Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discoloration of ceramic products.
Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm) ?
Froth floatation
Froth floatation is the most suitable for treating
sulphide ores
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/ton
Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is
0.2 to 0.8
The value of ‘angle of nip’ is generally about
32°
Highly viscous liquids & pastes are agitated by
multiple blade paddles
Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.
metalliferrous ores
Sulphuric acid mist is arrested by using a __________ scrubber.
venturi
The main size reduction operation in ultrafine grinders is
attrition
In case of a hammer crusher,
all (a), (b) and (c).
Jigging is a technique by which different particles can be
separated by particle size.
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
Balls for ball mills are never made of
lead
200 mesh screen means 200 openings per
inch
Energy consumed for crushing one ton of material ranges from __________ kWh.
0.5 to 1.5
For transporting pasty material, one will use a/an
screw colaveyor
__________ is the most commonly used ‘filter aid’.
Diatomaceous earth
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
A tube mill compared to a ball mill
has a higher length/diameter ratio.
Trommels separate a mixture of particles depending on their
size
Basic slag is not ground in
jaw crushers
Grindability of a material does not depend upon its
size
Shape factor for a cylinder whose length equals its diameter is
1.5
In case of a hammer crusher, the
rotor shaft carrying hammers can be vertical or horizontal.
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
Dust laden air can be purified using a
cyclone separator
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
__________ mixer is used for de-vulcanisation of rubber scrap & making water dispersion & rubber solution.
Banbery
Which of the follwoing mechanical conveyors does not come under the division ‘scrapers’ ?
Bucket elevators
Which of the following mechanical conveyors does not come under the division ‘carriers’ ?
Screw conveyor
Screen capacity is not a function of
atmospheric humidity.
Vacuum is applied in __________ zone, in case of a general type continuous rotary drum vacuum filter.
all (a), (b) & (c)
Which of the following is a vacuum filter ?
Rotary disc filter
Pine oil used in froth floatation technique acts as a/an
frother
Length/diameter ratio of a ball mill is
< 1
Feed size of ≥ 25 cms can be accepted by
jaw crusher
Which is the most suitable conveyor for transportation of sticky material ?
Screw conveyor
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
Filtration of water in a paper mill is done by a/an __________ filter.
open sand
Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is
1
Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is
<10
Moore filter is a __________ filter.
leaf
Maximum size reduction in a ball mill is done by the, __________ action.
impact
Ball mill is used for
fine grinding
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
In case of a ball mill,
coarse feed requires a larger ball
Flow of filtrate through the cake in a plate and frame filter press is best described by the __________ equation.
Kozney-Karman
increasing the capacity of a screen __________ the screen effectiveness.
decreases.
Bond crushing law
calls for relatively less energy for the smaller product particles, than does the Rittinger law.
The controlling resistance in a rotary drum vacuum filter is the __________ resistance.
cake
Which of the following is used for primary crushing of very hard lumpy materials ?
Gyratory crusher
Coal is finally pulverised to 200 mesh size for burning in boilers by a
ball mill
Crushing efficiency is the ratio of the
surface energy created by crushing to the energy absorbed by the solid.
The resistance offered by the filter used in a bag filter is proportional to (where, c = dust concentration, and s = particle size )
c/s
The crushed material received for separation is called feed or
heading
For spheres, volume shape factor is given by
π/6(=V/D3)
__________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals.
Selectivity index
Cement clinker is reduced to fine size by a
tube mill
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
The operating speed of a ball mill should be __________ the critical speed.
less than
Use of baffles in agitators help in minimiZing the __________ tendency.
both (a) & (b)
Fibrous material is broken by a
squirrel-cage disintegrator
__________ are used for the separation of coarse particles from a slurry of fine particles.
Classifiers
Out of the following size reduction equipment, the maximum feed size can be accepted by the
jaw crusher
__________ is the most suitable for compounding rubber and plastic solids.
Banbery mixer
Bucket elevators are not suitable for the vertical lifting of __________ materials.
sticky
The most common filter aid is
diatomaceous earth
For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the __________ filter.
sand
For separation of sugar solution from settled out mud, we use a __________ filter.
centrifugal
The sphericity of a cylinder of 1 mm diameter and length 3 mm is
0.9
Pulverised coal passing through 200 mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 mesh screen will have a dia of __________ mm.
0.30
What is the selectivity index, if the grade of tailings & concentrate is the same ?
1
The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a
boundary mixer.
Traces of solids are removed from, liquid in a
clarifier
__________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.
Minimum size
The speed of a rotary drum vacuum filter may be about __________ rpm.
1
For achieving maximum capacity of the ball mill, the ball charge should be equal to about __________ percent of the ball mill volume.
50
Electrical energy consumed by a jaw crusher is not a function of the
none of these
Mesh indicates the number of holes per
linear inch
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).
((S/V)p)^1/2
Colloid mills achieve size reduction mainly by
attrition
Trommels employ __________ for screening of materials.
punched plate
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
Size reduction mechanism used in Jaw crushers is
compression
A widely used size reduction equipment for __________ is Bradford breaker.
coal
Ultra centrifuges are used for the separation of __________ solid particles.
colloidal
A. __________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end.
compartment
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
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
both (a) & (b).
Specific surface area is the surface area of a unit __________ of materials.
either (a) or (b)
Size reduction does not occur due to compression in case of
rod mills
Which of the following represents the plot of filtrate volume versus time for constant pressure filtration ?
Parabola
Driving force in case of filtration by a centrifuge is the
centrifugal pressure exerted by the liquid.
Rod mills employed for grinding
all ‘a’, ‘b’ & ‘c’.
Production rate __________ with increased fineness, with a given energy input to the size reduction machine
decreases
Gold ore concentration is mostly done using
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
Mixing of light fine powder such as insecticides is done by
impact wheels
Run of mine (ROM) coal is crushed by a __________ for use in domestic ovens.
hammer crusher
Size reduction of asbestos and mica is done by
hammer mills
The unit of specific cake resistance is
gm/cm2
The study on washability of coal is done by using the __________ technique.
heavy media separation
Horsepower required for a roll crusher is directly proportional to its
both (a) & (b).
__________ conveyor is the most suitable for long distance transportation of cold, non-abrasive granular/irregular shape/fine materials.
Belt
A pebble mill
both (b) and (c).
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°
Moisture can be removed from lubricating oil using
tubular centrifuge
Pick out the wrong statement.
Crushing efficiency is the ratio of the energy absorbed by the solid to the surfaces energy created by crushing.
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
Which of the following terminology is not used for size reduction of materials to fine sizes or powders?
Compression
A tube mill as compared to a ball mill
employs smaller balls.
all (a), (b) and (c).
The specific cake resistance for compressible sludges is a function of the pressure drop
over cake
Addition of filter aid to the slurry before filtration is done to …… of the cake.
increase the porosity
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
Which of the following gives the crushing energy required to create new surface ?
Rittinger’s law
Which of the following clay mixing devices is vacuum operated for deairation of clay?
Pug mill
Pick out the material having minimum Rittinger’s number.
Quartz
__________ mills are termed as impactors.
Hammer
In case of a revolving mill, wet grinding compared to dry grinding
none of these.
In filtration, the use of ‘filter aid’ helps in
deplugging the filter medium.
Gizzlies are used for separating __________ solids.
fine
To get a fine talc powder from its granules, the equipment used is
ball mill
For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is
230
Width and speed of a conveyor belt depends upon the __________ of the material.
both (a) & (b)
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
all (a), (b) and (c).
Pick out the wrong statement
Capacity of crusher in choke feeding is increased
Tank filter (e.g., Nutsch filter) is
used for small scale filtration work.
Which of the following size reduction equipment employs mainly attrition for ultrafine grinding ?
all (a), (b) and (c)
In bag filters, filter fabrics are never made of
metallic wire woven mesh
Use of ‘grinding aids’ is done in __________ grinding.
dry
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
Which of the following is the most suitable filter for separation of abrasive solids suspended in a corrosive liquid ?
Vacuum filter
All resistances during washing of cake
remain constant
A __________ mixer resembles a ball mill without balls.
tumbling
__________ conveyor is the most suitable for short distance transportation of non-abrasive loose materials like garbage, grain, food wastes etc.
Flight
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 ∝ Re0.0
As the product becomes finer, the energy required for grinding
increases
Gyratory crushers compared to the reciprocating jaw crushers
have greater capacity per unit of discharge area.
The important dimensional group involved in the power requirement calculation in mixing operation is the __________ number.
both (a) & (b)
Rittinger’s crushing law states that
work required in crushing is proportional to the new surface created
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’ ?
Both (b) and (c)
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
General mechanism of size reduction in intermediate and fine grinder is by
impact and attrition.
Sphericity of pulverised coal is
<1
The reduction ratio for fine grinders is
as high as 100
A straight line is obtained on plotting reciprocal of filtration rate vs. the volume of filtrate for __________ flow of filtrate.
incompressible cake and laminar
Which of the following is the hardest material ?
Corundum
The work index in Bond’s law for crushing of solids has the following dimensions
kWh/ton
Ore concentration by jigging is based on the difference in the __________ of the particles.
specific gravities
Reduction ratio of crushers is the
ratio of feed opening to discharge opening.
Size measurement of ultrafine particles can be best expressed in terms of
surface area per unit mass
Which is a secondary crusher for a hard & tough stone ?
Cone crusher
Cyclones are used primarily for separating
solids from fluids
There is practically no alternative/competitor to __________ in the beneficiation treatment of sulphide ores.
froth floatation
Temperature of the product during ultrafine grinding
increases
Separation of materials of the same density based on their sizes by using then-different rates of flow is called
sizing
For a sphere falling in the constant drag co-efficient regime, its terminal velocity depends on its diameter (d) as
d2
Separation of isotopes is generally done using a/an __________ centrifuge.
ultra
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
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.
Chance process is used for the
cleaning of coal.
Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are
silicates & phosphates
In case of a plate and frame filter press, filtrate flow through the cake follows __________ flow.
laminar
Molten ammonium nitrate is mixed with ground limestone in fertilizer plant in a
pug mill
Which of the following is not used as filter aid?
Rice husk
Sphericity of raschig ring (whose length and diameter are equal) is
1
Which of the following screens has the maximum capacity ?
Vibrating screen
Mixing mechanism employed in a pan mixer is by
mulling
Which of the following is a batch sedimentation equipment ?
Filter thickener
Stamp mills are generally used for crushing
gold ores
The most suitable equipment for the transportation of 200 mesh size particles is a
pneumatic conveyor
Raw materials are charged in the iron blast furnace using
skip hoist
The most efficient equipment for the removal of sub-micronic dust particles from blast furnace gas is the
electro-static precipitator
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
Size reduction of moulding powders, waxes, resins & gums are done in a __________ mill.
both (a) & (b)
For beneficiation of iron ore, the most commonly used method is
jigging & tabling.
Vibrating screens are used for handling large tonnages of materials. The vibrating motion is imparted to the screening surface by means of
either (a), (b) or (c).
Screen capacity is proportional to (where, S = screen aperture)
S
The inlet pressure in a constant rate filtration
increases continuously
A __________ employs a set of screen across a flow channel for the separation of dirt/rust from a flowing liquid stream.
strainer
With increase in the pressure drop across the cake, the specific cake resistance for the compressible sludge
increases
In a grinding operation, the limiting particle size is the size of the __________ particle in the sample.
neither (a) nor (b)
A propeller agitator
produces mainly axial flow.
A filter press is
a batch filter.
Pick out the wrong statement
200 mesh screen has 200 openings per linear cm.
Reciprocal of sphericity is termed as the
shape factor
The filtrate flow rate in constant pressure filtration
continuously decreases.
Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is __________ microns.
< 74
Size reduction of ice and gypsum can be accomplished suitably by a __________ crusher.
toothed roll
__________ centrifuge is the most suitable for separation of non-friable crystals.
Perforated horizontal basket continuous
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
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.
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
The ratio of the actual mesh dimension of Taylor series to that of the next smaller screen is
Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle).
Squre rooto of 2
The main differentiation factor between tube mill and ball mill is the
length to diameter ratio.
Limestone is normally crushed in a
hammer crusher
Xanthates are used in the froth floatation process as a/an
collector
Pick out the correct statement.
both (b) and (c).
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
Use of grinding aids results in the
neither (a) nor (b).
A belt conveyor used for the transportation of materials can run upto 1 km.
all (a), (b) and (c).
not used as a surface active agent in a flocculation operation
Quartz
__________ mill is not a revolving mill.
Cage
For the transportation of ultrafine particles, the equipment used is a……..conveyor.
pneumatic
During filtration operation, the filtrate encounters the resistance of the
all (a), (b) and (c)
Filtration rate does not depend upon the
none of these.
is a fine crusher
Toothed roll crusher
__________ is a cohesive solid.
Wet clay
The optimum moisture content in solids to be crushed/ground ranges from __________ percent.
3 to 4
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
In classification, particles are said to be equal settling, if they have the same terminal velocities in the
both (b) and (c)
Dispersion of a gas through liquid is done by using a
sparger
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.
Removal of activated carbon from glycerine is done by
plate and frame filter
What is the reduction ratio in a fine crushing operation having following feed and product sizes?
Parameters Unit maximum Minimum
Feed size mm 20 10
Product size mm 10 5
2
Pick out the wrong statement.
Cake resistance is independent of the pressure drop.
oxides is not present in hematite iron ore
Cobalt oxide
Ribbon blenders are exclusively meant for
non-flowing powder and thin pastes.
In closed circuit grinding as compared to open circuit grinding, the
operation is economical.
Pick out the correct statement.
A hopper is a small bin with a sloping bottom.
Gelatinous solid (which plug the septum) can be filtered by a __________ filter.
precoat
During the washing of cake
all the resistances are constant.
The opening of a 200 mesh screen (Taylor series) is
0.0074 cm
A gravity decanter is meant for the separation of two __________ density.
immiscible liquids of different
The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the __________ filter.
sand
Separation of solid particles based on their densities is called
sorting
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
__________ are mixed using ribbon blenders.
Dry powders
During agitation of liquids, the
all (a), (b) and (c).
For crushing of solids, the Rittinger’s law states that the work required for crushing is proportional to
the new surfac
the new surface created.
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
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
Wheat is ground into flour in a
roller crusher
Gravity stamp mill is meant for the __________ crushing.
fine
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.
Traces of liquid tar fog present in coke oven gas is separated using
electrostatic precipitator
electrostatic precipitator
1.34
Choke crushing (in case of a Jaw crusher) compared to free crushing
consumes more power.
Vacuum filter is most suitable for the
none of these.
The porosity of a compressible cake is
minimum at the filter medium.
conveyors cannot be recommended for transportation of abrasive materials ?
Flight conveyor
Separation of materials into products based on the difference of their sizes is called
sizing
Hot, lumpy & abrasive materials are best transported by using a/an __________ conveyor.
apron
Additives used for promoting the floccula-tion of particles is a/an
both (a) & (b)
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
not a cutting machine?
Tube mills
Weber number is significant and is concerned with the
dispersion of liquid in liquid.
dispersion of liquid in liquid.
density
Vibrating screens have capacity in the range of __________ tons/ft2 .mm mesh size.
0.2 to 0.8
To remove very small amount of tiny solid impurities from liquid, we use a
coagulant
Energy consumption in a crusher decreases with increase in the
all (a), (b) & (c).
The term ‘angle of nip’ is concerned with the operation of the __________ crushers.
roll
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
0.50
_________ is used for producing a thick suspension from a thin slurry.
Pressure filter thickener
Sphericity of raschig ring (whose length and diameter are equal) is
1
the crushing energy required to create new surface
Rittinger’s law
Mixing mechanism employed in a pan mixer is by
mulling
Chance process is used for the
cleaning of coal.
Raw materials are charged in the iron blast furnace using
skip hoist
Stamp mills are generally used for crushing
gold ores
Handling of ashes and similar materials can be done best by a __________ conveyor.
drag or slat
For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a
Buhrstone mill
Which of the following must be stored in silos and not in open yard ?
High V.M. bituminous coal
