Particle Technology Flashcards

1
Q

Equivalent Diameter is the diameter of the sphere having the same

A

ratio of surface to volume as the actual volume

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2
Q

Sphericity of Cylinder having equal L and D

A

0.87

S = π⅓ (6V)⅔ ÷ SA
S = 6V ÷ (SA*D)

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3
Q

Sphericity of hedrons

A

Tetra - 0.67
Hexa - 0.81
Octa - 0.84
Dodeca - 0.91
Icosa - 0.94

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4
Q

Units of measurements used for different sizes of particles

A

Coarse - mm, in, cm
Fine - mesh or screen size
Very fine - microns, nano
Ultrafine - SA/mass (e.g., m²/g)

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5
Q

Short distance transportation of grain gravel, sand is done using

A

screw conveyor

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6
Q

Power requirement of ball mill is proportional to

A

D^2.5

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7
Q

Screen for sizing very fine materials

A

Vibrating Screen

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8
Q

Plate and frame filter operates by

A

pressure

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9
Q

Tabular bowl centrifuges operate at ____ as/than disk bowl centrifuge

a. lower speed
b. higher speed
c. same speed

A

higher speed

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10
Q

Pebbles used in pebble mills are made of

A

flint or porcelain

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11
Q

Agitator for fibrous and dense slurries

A

Cone type

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12
Q

Centrifuge used in sugar mills

A

Suspended batch basket

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13
Q

Mesh sizes of this screen is arranged from smallest to largest. Used for powdered and granular feeds

A

Reciprocating screens

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14
Q

Mesh number is defined as

A

Number of apertures per linear inch

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15
Q

How to relate mesh number to screen opening/aperture?

A

Mesh Number (Aperture + Wire Diameter) = 1

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16
Q

Screen interval of Tyler Standard Sieve Series

A

√2

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17
Q

United States Sieve Series screen interval is

A

⁴√2

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18
Q

Cumulative Analysis or Plot in screening

A

Larger than Dp - mass fraction is the overflow of the mesh

Smaller than Dp - mass fraction is the underflow of the mesh

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19
Q

Relationship of screen effectiveness and screen capacity

A

Inverse

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20
Q

Ball mills and tube mills with flint or porcelain balls are used for size reduction of

A

non-metallic ores

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21
Q

Size reduction of ____ is accomplished in steam heated rollers and roll crushes

a. waxes
b. resins
c. gums
d. rubber

A

Rubber

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22
Q

Filter media is used to

A

increase the porosity if cake

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23
Q

Froth floatation is mist suitable for

a. iron ores
b. quartzite
c. sulfide ores
d. none

A

sulfide ores

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24
Q

Taggart’s formula

A

T=0.6LS

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25
Q

Equipment for Coarse, Hard Materials

A

Jaw crusher and Gyratory crusher

T/S² < 0.115 Jaw
T/S² > 0.115 Gyratory

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26
Q

Equipment for Coarse, Soft Materials ,e.g., gypsum, coal, ice, fire, shales, clay

A

Brandford breaker for coal
Tooth roll crusher (by pressure)
Hammer Mill
Squirrel Cage Disintegrator

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27
Q

Equipment for Intermediate size reduction

A

Crushing rolls (2 rolls rotating in opposite direction)
Cone crushers
Edge runner (clay industry)

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28
Q

Crushing roll, angle of nip formula

A

angle = 2@

cos @ = (r1 + b) ÷ (r1+r2)

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29
Q

Mill used in paint, pigment, cosmetics manufacturing

a. Ball mill
b. Pebble mill
c. Rod mill
d. Hammer mill

A

Pebble mill

30
Q

Speed when centrifuging (balls are carried iver due to very high speed) occurs in the mill

A

Critical speed

31
Q

Equipment for Ultrafine size reduction

A

Classifying Hammer Mill
Fluid Energy Mill
Agitated Mill
Colloid Mill

32
Q

Energy required for size reduction is proportional to the length of the initial and final diameters

A

Kick’s Law (n=1)

P/T = k ln (x1/x2)

33
Q

Energy requirement is proportional to the new surface created

A

Rittinger’s Law (n=2)

P/T = k (1/x2 - 1/x1)

34
Q

Rittinger’s formula given specific surface area and rittinger’s number

A

P/T = (Sp-Sf) / Rittinger’s No.

Rittinger’s Number = 1/Kr

35
Q

Energy requirement is proportional yo the square root of the surface to volume ratio of the product

A

Bond’s Law (n=1.5)

P/T = K (x2 -½ — x1 -½)

36
Q

Cleaning of fine coal dust (<0.5 mm)

A

Froth floatation

37
Q

Range of compressibility coefficient of commercial compressible cake obtained in filtration is

a. 0.01 to 0.1
b. 0.1 to 0.5
c. 0.2 to 0.8
d. 0.8 to 1.2

A

0.2 to 0.8

38
Q

The value of angle of nip is generally about

A

32°

39
Q

Sulfuric acid mist is arrested by using ____ scrubber

A

venturi

40
Q

Main size reduction in ultra-fine grinders

a. compression
b. attrition
c. impact
d. cutting

A

Attrition

coarse - compression
fine - impact
very fine - attrition

41
Q

Jigging is a technique by which particles can be separated by

a. particle density
b. particle shape
c. particle size
d. all

A

particle size

42
Q

A cage mill is a ____ mill

a. roll
b. vibratory
c. impact

A

impact mill

43
Q

Diatomaceous Earth is an example of

A

filter aid

44
Q

Separator for milk cream

a. disc bowl centrifuge
b. sharpies supercentrifuge
c. batch basket centrifuge

A

disc bowl

45
Q

Grindability is independent of

a. size
b. elasticity
c. hardness
d. tougness

A

size

46
Q

Shape factor for a cylinder whose L=D

A

1.5

47
Q

Dust laden air is purified using

a. cyclone separator
b. bag filter
c. tubular centrifuge

A

cyclone separator

48
Q

Higher rittinger’s number of material indicates _____ grindability

a. poorer
b. better

A

better

49
Q

Mixer used for devulcanization of rubber scarp and making water dispersion and rubber solution

a. Banbery
b. Tumbler
c. Muller

A

Banbery

50
Q

Conveyors under “scrapers”

A

Ribbon
Flight
Drag

51
Q

L/D of ball mill us

a. 1
b. greater than 1
c. less than 1

A

less than 1

52
Q

Conveyor for sticky material

A

Screw conveyor, which is not part of “carrier” division

53
Q

Filtration of water in a paper mill is done by using what filter

a. open sand
b. leaf
c. plate and frame
d. sparkler

A

open sand

54
Q

Also called as Moore filter

A

Leaf filter

55
Q

For ball mill, coarse particles will require _____ balls

a. large
b. small

A

large

56
Q

Flow if filtrate through a cake in a PFF is best described by what equation

A

Kozney-Karman

57
Q

Resistance offered by the bag filter is proportional to

A

concentration of dust/particle size

58
Q

Mill for cement clinker

a. ball
b. rod
c. tube
d. hammer
e. pebble

A

tube

59
Q

Geometric mean of the relative rejections and the relative recoveries of 2 minerals

A

Selectivity index

60
Q

Mixer for rubber and plastic solids

A

Banbery

61
Q

Maximum attainable velocity

A

Free settling or terminal velocity

62
Q

b and n for the three ranges of particle motion

A

Stokes 24,1 Re <2
Intermediate 18.5,0.6 Re 2-500
Newton 0.44,0 Re >500

K = Ar⅓ >3.3 - 44<

63
Q

Rate of settling is not constant as the movement of particle is impeded by nearby particles

A

Hindered Settling

64
Q

Separation of sugar solution from settled out mud, we use ____ filter

A

centrifugal

65
Q

Mixing light fine powder of insecticide is done by

A

Impact wheel

66
Q

Size reduction of mica and asbestos is done in

a. gyratory crusher
b. crushing rolls
c. hammer mill

A

hammer mill

67
Q

Moisture can be removed from lubricating oil using

A

tubular centrifuge

68
Q

In tabling, table/deck is inclined from horizontal at an angle of

A

2-5°

69
Q

Gizzlies are used to separate __ solids

a. coarse
b. fine
c. very fine

A

fine

70
Q

Reduction ratio of fine grinders

A

up to 100

71
Q

Reduction ratio

A

Ratio of feed opening to discharge opening

72
Q

Separation of isotopes is done using

A

ultra-centrifuge