Particle Technology

Question 1

Filter aid is used

Answer 1

To increase the porosity of the cake

Question 2

The porosity of compressible cake is

Answer 2

Minimum at the filter medium

Question 3

Which of the following may prove unsuitable for filtering volatile liquids?

A. Pressure filter
B. Centrifugal filter
C. Gravity filter
D. Vacuum filter

Answer 3

D. Vacuum filter

Question 4

Increasing the capacity of screen

Answer 4

Decreases the screen effectiveness

Question 5

Screen efficiency is

Answer 5

Recovery x rejection

Question 6

As particle size is reduced

Answer 6

Screening becomes progressively more difficult

Question 7

A screen is said to be blinded when

Answer 7

The screen is plugged with solid particles

Question 8

The material passing one screen surface and retained on a subsequent surface is called

Answer 8

Intermediate material

Question 9

In screen analysis, notation + 5mm/ -10 mm means passing through

Answer 9

10 mm screen and retained on 5 mm screen

Question 10

Mesh number indicates the number of holes per

Answer 10

Linear inch

Question 11

Sphericity of a cylinder whose length equals its diameter

Answer 11

0.87

Question 12

Size measurement of ultrafine particles can be best expressed in terms of

Answer 12

Square area/ unit mass

Question 13

Example of a hard material

Answer 13

Sapphire

Question 14

For the preliminary breaking of hard rock, we use

Answer 14

Gyratory crusher

Question 15

Size reduction mechanism used in jaw crushers is

Answer 15

Compression

Question 16

To get ultrafine particles, the equipment used is

Answer 16

Fluid energy mill

Question 17

Maximum size reduction in a ball mill is done by

Answer 17

Impact

Question 18

The operating speed of a ball mill should be

Answer 18

Less than the critical speed

Question 19

As the product becomes finer, the energy required for grinding

Answer 19

Increases

Question 20

The operation by which solids are separated from liquids due to difference in the respective densities is

Answer 20

Sedimentation

Question 21

Forces acting on a particle settling in fluid are

Answer 21

Gravitational, centrifugal, buoyant, drag forces

Question 22

Drag is defined as the force exerted by the

Answer 22

Fluid on the solid in a direction opposite to flow

Question 23

Stoke’s Law is valid when the particle Reynolds number is

Answer 23

1

Question 24

The terminal velocity of a small sphere settling in a viscous fluid varies as the

Answer 24

Inverse of fluid viscosity

Question 25

Buoyant force

Answer 25

Depends on the weight of the floating body

Question 26

Terminal velocity is

Answer 26

Constant velocity with no acceleration

Question 27

In hindered settling, particles are

Answer 27

Near each other

Question 28

If the radius of a basket centrifuge is halved and the rpm is doubled, then

Answer 28

Centrifugal force is doubled