S3

Question 1

Out of the following size reduction equipments, the maximum feed size can be accepted by the

Answer 1

jaw crusher

Question 2

Bucket elevators are not suitable for the vertical lifting of __________ materials.

Answer 2

sticky (e.g. clay paste)

Question 3

The most common filter aid is

Answer 3

diatomaceous earth

Question 4

For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the __________ filter.

Answer 4

sand

Question 5

For separation of sugar solution from settled out mud, we use a __________ filter.

Answer 5

centrifugal

Question 6

The sphericity of a cylinder of 1 mm diameter and length 3 mm is

Answer 6

0.9

Question 7

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.

Answer 7

0.30

Question 8

What is the selectivity index, if the grade of tailings & concentrate is the same?

Answer 8

1

Question 9

The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a

Answer 9

boundary mixer.

Question 10

Traces of solids are removed from, liquid in a

Answer 10

clarifier

Question 11

__________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.

Answer 11

Minimum size

Question 12

The speed of a rotary drum vacuum filter may be about __________ rpm.

Answer 12

1

Question 13

Colloid mills achieve size reduction mainly by

Answer 13

attrition

Question 14

Mesh indicates the number of holes per

Answer 14

linear inch

Question 15

For achieving maximum capacity of the ball mill, the ball charge should be equal to about __________ percent of the ball mill volume.

Answer 15

50

Question 16

According to Bond crushing law, the work required to form particle of size ‘D’ from very large feed is (where (S/V)pand (S/V)fare surface to volume ratio of the product and feed respectively).

Answer 16

sqrt (S/V)p

Question 17

Which of the following gives the work required for size reduction of coal to -200 mesh in a ball mill most accurately?

Answer 17

Rittinger’s law

Question 18

Electrical energy consumed by a jaw crusher is not a function of the

Answer 18

none of these

Question 19

Size reduction mechanism used in Jaw crushers is

Answer 19

compression

Question 20

Trommels employ __________ for screening of materials.

Answer 20

punched plate

Question 21

A widely used size reduction equipment for __________ is Bradford breaker.

Answer 21

Coal

Question 22

Ultra centrifuges are used for the separation of __________ solid particles.

Answer 22

colloidal

Question 23

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.

Answer 23

compartment

Question 24

Size reduction does not occur due to compression in case of

Answer 24

rod mills

Question 25

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

Answer 25

0.0184

Question 26

Which of the following represents the plot of filtrate volume versus time for constant pressure filtration?

Answer 26

Parabola

Question 27

Driving force in case of filtration by a centrifuge is the

Answer 27

centrifugal pressure exerted by the liquid.

Question 28

Rod mills employed for grinding

Answer 28

all 'a', 'b' & 'c'.

Question 29

Production rate __________ with increased fineness, with a given energy input to the size reduction machine.

Answer 29

decreases

Question 30

Mixing of light fine powder such as insecticides is done by

Answer 30

impact wheels

Question 30

Gold ore concentration is mostly done using

Answer 30

Tabling

Question 31

Run of mine (ROM) coal is crushed by a __________ for use in domestic ovens.

Answer 31

hammer crusher

Question 32

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?

Answer 32

Sphere

Question 33

The unit of specific cake resistance is

Answer 33

gm/cm2

Question 33

Size reduction of asbestos and mica is done by

Answer 33

hammer mills

Question 34

The study on washability of coal is done by using the __________ technique.

Answer 34

heavy media separation

Question 35

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

Answer 35

0.6

Question 36

__________ conveyor is the most suitable for long distance transportation of cold, non-abrasive granular/irregular shape/fine materials.

Answer 36

Belt

Question 37

The specific cake resistance for compressible sludges is a function of the pressure drop

Answer 37

over cake

Question 38

Moisture can be removed from lubricating oil using

Answer 38

tubular centrifuge

Question 39

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

Answer 39

2 to 5°

Question 40

Pick out the wrong statement.

Answer 40

Crushing efficiency is the ratio of the energy absorbed by the solid to the surfaces energy created by crushing.

Question 41

Addition of filter aid to the slurry before filtration is done to ...... of the cake.

Answer 41

increase the porosity

Question 42

Which of the following terminology is not used for size reduction of materials to fine sizes or powders?

Answer 42

Compression

Question 43

A tube mill as compared to a ball mill

Answer 43

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

Question 44

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

Answer 44

kW. sec/kg