Mechanical Operations

Question 1

Sphericity of raschig ring (whose length and diameter are equal) is

Answer 1

1

Question 2

Mixing mechanism employed in a pan mixer is by

Answer 2

mulling

Question 3

The filtrate flow rate in constant pressure filtration

Answer 3

continuously decreases.

Question 4

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/m^3 here,V=πN.Dwhere,N= speed of the rolls in rotation per second (rps)D= diameter of rolls, m)

Answer 4

3.6 V.W.Dr.ρ

Question 5

The inlet pressure in a constant rate filtration

Answer 5

increases continuously

Question 6

Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is __________ microns.

Answer 6

< 74

Question 7

Screen capacity is proportional to (where,S= screen aperture)

Answer 7

S

Question 8

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

Answer 8

sedimentation

Question 9

With increase in the pressure drop across the cake, the specific cake resistance for the compressible sludge

Answer 9

increases

Question 10

200 mesh screen has 200 openings per linear cm.

Answer 10

Wrongggg

Question 11

Xanthates are used in the froth floatation process as a/an

Answer 11

collector

Question 12

Limestone is normally crushed in a

Answer 12

hammer crusher

Question 13

Filtrate flow rate in case of a rotary drum vacuum filter (in whichRm< <Rc) is proportional to __________ and the cycle time (where, μ = filtrate viscosityRm= filter medium resistanceRc= cake resistance ).

Answer 13

1/√μ

Question 14

The main differentiation factor between tube mill and ball mill is the

Answer 14

length to diameter ratio

Question 15

The optimum moisture content in solids to be crushed/ground ranges from __________ percent.

Answer 15

3 to 4

Question 16

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.

Answer 16

2.5 times

Question 17

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.

Answer 17

Work Index

Question 18

Removal of activated carbon from glycerine is done by

Answer 18

plate and frame filter

Question 19

What is the reduction ratio in a fine crushing operation having following feed and product sizes?


Answer 19

2

Question 20

For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a

Answer 20

Buhrstone mill

Question 21

Handling of ashes and similar materials can be done best by a __________ conveyor.

Answer 21

drag or slat

Question 22

With increase in drum speed, in a rotary drum filter, the filtration rate

Answer 22

increases

Question 23

200 mesh seive size corresponds to __________ microns.

Answer 23

74

Question 24

What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls ?

Answer 24

32°

Question 25

Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation ?

Answer 25

Jaw Plates

Question 26

. 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

Answer 26

1 μm/s

Question 27

In froth floatation, chemical agent added to cause air adherence is called

Answer 27

collector

Question 28

The sphericity of a solid particle of cubical shape

Answer 28

(π/6)^1/3

Question 29

Kick's crushing law is, P/m = K . ln(Dsa/Dsb)

Answer 29

Correctuee

Question 30

Compressibility co-efficient for an absolutely compressible cake is

Answer 30

1

Question 31

Mixing of plastic solids is generally facilitated by

Answer 31

kneading

Question 32

Helical screw agitator is used for

Answer 32

mixing highly viscous pastes.

Question 33

For raschig rings, the sphericity is

Answer 33

< 1

Question 34

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.

Answer 34

500

Question 35

Wet grinding in a revolving mill __________ as compared to dry grinding.

Answer 35

increases capacity

Question 36

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))

Answer 36

Db^2 = K.Df

Question 37

Pine oil and cresylic acid are used as __________ in the froth floatation process.

Answer 37

frother

Question 38

Filter medium resistance is important during the __________ of filtration.

Answer 38

early stages

Question 39

__________ baffles are provided in ball mills.

Answer 39

Horizontal

Question 40

__________ mill is not used for grinding wheat into flour and for milling of cereals & other vegetable products.

Answer 40

Pebble

Question 41

Conveyor that is not recommended for transportation of abrasive materials.

Answer 41

Flight conveyor

Question 42

Hot, lumpy & abrasive materials are best transported by using a/an __________ conveyor.

Answer 42

apron

Question 43

Kick's law relates to

Answer 43

energy consumption

Question 44

The maximum slope of a belt conveyor can be

Answer 44

30°

Question 45

The filter medium resistance is controlled by

Answer 45

both pressure drop and flowrate

Question 46

Most effectively used equipment for clarification of lube oil and printing ink?

Answer 46

Sharpies Centrifuge

Question 47

Size reduction of fibrous materials like wood, asbestos, mica etc. is done by a disintegrator exemplified by the

Answer 47

cage mill

Question 48

The material is crushed in a gyratory crusher by the action of

Answer 48

compression

Question 49

The equivalent diameter of channel of a constant non-circular cross-section of 3 cm by 6 cm will be __________ cms.

Answer 49

2

Question 50

Mass flow of granular solid (M) through a circular opening of dia, D  follows

Answer 50

M ∝ D^3

Question 51

In paint industries, blending of light paste is done by using a

Answer 51

charge can mixer

Question 52

. 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

Answer 52

0.50

Question 53

__________ is used for producing a thick suspension from a thin slurry.

Answer 53

Pressure filter thickener

Question 54

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).

Answer 54

Peclet

Question 55

The term 'angle of nip' is concerned with the operation of the __________ crushers.

Answer 55

roll

Question 56

Vibrating screens have capacity in the range of __________ tons/ft2 .mm mesh size.

Answer 56

0.2 to 0.8

Question 57

Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid.

Answer 57

density

Question 58

Cake resistance is independent of the pressure drop.

Answer 58

Wrongggg

Question 59

A hopper is a small bin with a sloping bottom.

Answer 59

Correctuee