Which of the following gives the crushing energy required to create new surface ?

For crushing of solids, the Rittinger's law states that the work required for crushing is proportional to

A

The new surface created

B

The size reduction ratio

C

The change in volume due to crushing

D

None of these

What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls?

A

16°

B

32°

C

40°

D

46°

Choke crushing (in case of a Jaw crusher) compared to free crushing

A

Results in increased capacity

B

Consumes less power

C

Consumes more power

D

Both A and C

Crushing resistance required to crush the rivet per pitch length is

A

$${\text{pd}}{\sigma _{\text{c}}}$$

B

$${\text{pt}}{\sigma _{\text{c}}}$$

C

$${\text{ndt}}{\sigma _{\text{c}}}$$

D

$$\left( {{\text{p}} - {\text{d}}} \right){\text{t}}{\sigma _{\text{c}}}$$

The pull required to tear off the plate per pitch length is (where p = Pitch of rivets, t = Thickness of plates and $${\sigma _{\text{t}}},\,\tau $$ and $${\sigma _{\text{c}}}$$ = Permissible tensile, shearing and crushing stresses respectively)

A

$$\left( {{\text{p}} - 2{\text{d}}} \right){\text{t}} \times {\sigma _{\text{c}}}$$

B

$$\left( {{\text{p}} - {\text{d}}} \right){\text{t}} \times \tau $$

C

$$\left( {{\text{p}} - {\text{d}}} \right){\text{t}} \times {\sigma _{\text{t}}}$$

D

$$\left( {2{\text{p}} - {\text{d}}} \right){\text{t}} \times {\sigma _{\text{t}}}$$

Energy consumed for crushing one ton of material ranges from __________ kWh.

A

0.01 to 0.1

B

0.5 to 1.5

C

2 to 3.5

D

4 to 5

When you are given a set of tables and asked to create a database to store their data, the first step is to create the new database.

A

True

B

False

Which of the following is used for primary crushing of very hard lumpy materials?

A

Toothed roll crusher

B

Gyratory crusher

C

Ball mill

D

Tube mill

Which of the following crushing laws is most accurately applicable to the fine grinding of materials ?

A

Bond's crushing law

B

Kick's law

C

Rittinger's law

D

None of these

The work index in Bond's law for crushing of solids has the following dimensions

A

No units (dimensionless)

B

kWh/ton

C

kW/ton

D

$${\text{kWh}}.{{\text{m}}^{\frac{1}{2}}}/{\text{ton}}$$

Which of the following gives the crushing energy required to create new surface ?

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