Screening

Question 1

it is a unit operation where a mixture of particles of various sizes is separated into two or more portions

Answer 1

screening

Question 2

it is done by allowing the mixture to pass over a surface with openings or holes of desired sizes

Answer 2

screening

Question 3

Screening is in important in many aspects such as:

Answer 3

1. Preparing a product to be sold or to be prepared for succeeding unit operations.
2. An analytical technique to measure effectiveness of grinding or crushing operations.
3. It determines the value of a product.

Question 4

In analyzing particle size distribution of mixture of particles of various sizes, _______________ are used.

Answer 4

testing sieves

Question 5

these are series of screens constructed of wire mesh cloth, where the diameters of the wire and the spacing of the wires are specified

Answer 5

testing sieves

Question 6

it is the clear space/opening between individual wires of the screen

Answer 6

screen apertures

Question 7

this is the number of apertures per linear inch

Answer 7

mesh number

Question 8

relationship between mesh number and aperture

Answer 8

inversely proportional

Question 9

this is the relationship between the successive sizes of
screen openings in a series

Answer 9

screen interval

Question 10

200-mesh screen with wire 0.0021 in thick and screen aperture of 0.0029 in

Answer 10

tyler standard sieve series

Question 11

The sizes vary by a fixed ratio of √2.

Answer 11

tyler standard sieve series

Question 12

based on a screen aperture of 1-mm openings and sizes varying by 4√2

Answer 12

united states sieve series

Question 13

this measures how much material or particles a screen can handle

Answer 13

screen’s capacity

Question 14

this greatly affects the screening efficiency

Answer 14

screen’s capacity

Question 15

relationship between capacity and efficiency

Answer 15

inversely proportional

Question 16

this is added to increase contact and improve chances of particles to pass through

Answer 16

mechanical shaker

Question 17

5 types of screening equipment

Answer 17

1. Stationary screens and grizzlies
2. Gyrating screens
3. Vibrated screens
4. Oscillating screens
5. Reciprocating screens

Question 18

a grid of parallel metal bars set in an inclined stationary frame

Answer 18

Stationary screens and grizzlies

Question 19

a grid of parallel metal bars set in an inclined stationary frame

Answer 19

Stationary screens and grizzlies

Question 20

Only effective with very coarse free flowing solids and are used for sand, gravel, coal.

Answer 20

Stationary screens and grizzlies

Question 21

Casing and screens are gyrated in a vertical plane about a horizontal axis by an eccentric

Answer 21

Gyrating screens

Question 22

Finer screens are gyrated at the feed but are not gyrated at the discharge.

Answer 22

Gyrating screens

Question 23

these are used for large tonnages/ capacity screenin

Answer 23

vibrated screens

Question 24

They are characterized by high speed vibrations ranging from 1500 to 7200 vibrations/min. Used in chemical and fertilizer industries

Answer 24

vibrated screens

Question 25

these are characterized by low-speed oscillations of 300 to 400 rpm which uses silk cloth as screening material.

Answer 25

oscillating screens

Question 26

standard equipment for handling fine separations up to 300 mesh in light metal powders, powdered foods, and grains.

Answer 26

reciprocating screens

Question 27

standard equipment for handling fine separations up to 300 mesh in light metal powders, powdered foods, and grains.

Answer 27

reciprocating screens

Question 28

openings get blocked by particles

Answer 28

blinding

Question 29

relationship between feed rate end effiency

Answer 29

inversely proportional

Question 30

True or False: screening is s continuous process

Answer 30

true

Question 31

relationship between mesh number and size of openings

Answer 31

inversely proportional