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Parti > S3 > Flashcards

S3 Flashcards

1
Q

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

A

jaw crusher

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2
Q

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

A

sticky (e.g. clay paste)

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3
Q

The most common filter aid is

A

diatomaceous earth

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4
Q

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

A

sand

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5
Q

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

A

centrifugal

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6
Q

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

A

0.9

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7
Q

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.

A

0.30

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8
Q

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

A

1

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9
Q

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

A

boundary mixer.

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10
Q

Traces of solids are removed from, liquid in a

A

clarifier

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11
Q

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

A

Minimum size

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12
Q

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

A

1

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13
Q

Colloid mills achieve size reduction mainly by

A

attrition

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14
Q

Mesh indicates the number of holes per

A

linear inch

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15
Q

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

A

50

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16
Q

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).

A

sqrt (S/V)p

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17
Q

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

A

Rittinger’s law

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18
Q

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

A

none of these

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19
Q

Size reduction mechanism used in Jaw crushers is

A

compression

20
Q

Trommels employ __________ for screening of materials.

A

punched plate

21
Q

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

A

Coal

22
Q

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

A

colloidal

23
Q

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.

A

compartment

24
Q

Size reduction does not occur due to compression in case of

A

rod mills

25
Q

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

A

0.0184

26
Q

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

A

Parabola

27
Q

Driving force in case of filtration by a centrifuge is the

A

centrifugal pressure exerted by the liquid.

28
Q

Rod mills employed for grinding

A

all ‘a’, ‘b’ & ‘c’.

29
Q

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

A

decreases

30
Q

Mixing of light fine powder such as insecticides is done by

A

impact wheels

30
Q

Gold ore concentration is mostly done using

A

Tabling

31
Q

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

A

hammer crusher

32
Q

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?

A

Sphere

33
Q

The unit of specific cake resistance is

A

gm/cm2

33
Q

Size reduction of asbestos and mica is done by

A

hammer mills

34
Q

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

A

heavy media separation

35
Q

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

A

0.6

36
Q

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

A

Belt

37
Q

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

A

over cake

38
Q

Moisture can be removed from lubricating oil using

A

tubular centrifuge

39
Q

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

A

2 to 5°

40
Q

Pick out the wrong statement.

A

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

41
Q

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

A

increase the porosity

42
Q

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

A

Compression

43
Q

A tube mill as compared to a ball mill

A

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

44
Q

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

A

kW. sec/kg

Parti (9 decks)

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