S8

Question 1

Screen efficiency is

Answer 1

none of these

Question 2

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

Answer 2

Buhrstone mill

Question 3

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

Answer 3

drag or slat

Question 4

Which of the following must be stored in silos and not in open yard?

Answer 4

High V.M. bituminous coal

Question 5

Apron conveyors are used for

Answer 5

heavy loads & short runs.

Question 6

Sedimentation on commercial scale occurs in

Answer 6

rotary drum filters

Question 7

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

Answer 7

increases

Question 8

Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them.

Answer 8

Jaw crusher, Ball mill, Fluid energy mill

Question 9

200 mesh seive size corresponds to __________ microns.

Answer 9

74

Question 10

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

Answer 10

32°

Question 11

For a turbine agitated and baffled tank, operating at low Reynold’s number (based on impeller diameter), the power number (Np) varies withNReas

Answer 11

Np α 1/NRe

Question 12

Which of the following is not accomplished by agitation of liquids in agitators?

Answer 12

Blending of immiscible liquids.

Question 13

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

Answer 13

Jaw plates

Question 14

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 14

1 μm/s

Question 15

The specific surface of spherical particles is given by (whereDand ρ are diameter and density of particle).

Answer 15

6 / D . ρ

Question 16

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)

Answer 16

(Dp^2 /18 . ρs - ρ / μ) ω^2 r

Question 17

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

Answer 17

collector

Question 18

The sphericity of a solid particle of cubical shape is

Answer 18

(π/6)^1/3

Question 19

A cottrel precipitator makes use of the __________ for dusty air cleaning.

Answer 19

corrona discharge

Question 20

Pick out the correct statement.

Answer 20

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

Question 21

If radius of a batch basket centrifuge is halved & the r.p.m. is doubled, then the

Answer 21

centrifugal force is doubled.

Question 22

The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is

Answer 22

none of these

Question 23

Compressibility co-efficient for an absolutely compressible cake is

Answer 23

1

Question 24

Mixing of plastic solids is generally facilitated by

Answer 24

kneading

Question 25

Which of the following is not an industrial screening equipment?

Answer 25

Sharpies centrifuge

Question 26

Which of the following is not a wet classifier?

Answer 26

None of these

Question 27

Helical screw agitator is used for

Answer 27

mixing highly viscous pastes.

Question 28

For raschig rings, the sphericity is

Answer 28

<1

Question 29

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 29

500

Question 30

__________ mills are termed as disintegrators.

Answer 30

Cage

Question 31

Supporting legs of a plate and frame filter is normally made of

Answer 31

cast iron

Question 32

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

Answer 32

∑ i = 1 j Ni mi di^3 / ∑ i = 1 ∞ Ni mi di^3

Question 33

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

Answer 33

increases capacity

Question 34

A compressible cake has the

Answer 34

maximum porosity at the upstream side.

Question 35

Which of the following is not used as a filter medium in case of corrosive liquids?

Answer 35

Cotton fabric

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

Grinding characteristic of a material is given by its

Answer 38

HGI

Question 39

Which of the following is not a non-metalliferous mineral?

Answer 39

Cassiterrite

Question 40

Filter medium resistance is important during the __________ of filtration.

Answer 40

early stages.

Question 41

Float and sink test determines the possibility of cleaning of coal by a process based on the

Answer 41

gravity separation

Question 42

Mixer used for rubber compounding is

Answer 42

banbury internal mixer

Question 42

__________ baffles are provided in ball mills.

Answer 42

Horizontal

Question 42

For spheres, the specific surface shape factor is given by

Answer 42

AD/V

Question 43

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

Answer 43

Pebble

Question 44

In case of a hammer crusher, the final product size depends on the

Answer 44

all (a), (b) and (c).