Final KB Qs Module 3: Communition, Liberation, Classification

Question 1

Why grind?

Answer 1

Grinding is all about enabling the separation of ‘valuable’ minerals from ‘nonvaluable minerals.

Question 2

Give Recovery vs size curve

Answer 2

Question 3

Name rock breaking equipment. (5)

Answer 3

1. Gyratory crusher
2. Jaw crusher
3. Roll crusher
4. Autogeneous mill
5. Semi-autogeneous mill

Question 4

Draw a single screen on a flowchart.

Answer 4

Question 5

Give the screen efficiency formula, and what can be said about u.

Answer 5

General assumption would be that u=1

Question 6

Give grinding media types.

Answer 6

1. Ball
2. Rod
3. Slug

Question 7

What is critical speed in mills?

Answer 7

This refers to the speed at which the media will be just pinned to the wall by centrifugal force. There will be no falling of the media.

Question 8

Give the critical speed formula. Explain variables.

Answer 8

D is mill diameter, d is media diameter

Question 9

Draw the forces acting on the media when the mill rotates.

Answer 9

Question 10

Give the critical angles associated formulas (2) plus the combined one.

Answer 10

Question 11

Give the Bond Work Index formula.

Answer 11

Question 12

Give the Power formula.

Answer 12

P = W ×T

Question 13

The power draw of a tumbling mill depends on which 2 variables?

Answer 13

1. Loading
2. rotational speed

Question 14

What are the 2 breakage mechanism in a tumbling mill?

Answer 14

1. Impact
2. Attrition

Question 15

Draw Power draw (relative to maximum power, P/Pmax) as a function of load

Answer 15

Question 16

How does Microwave Radiation work? Name materials behavior’s (3)

Answer 16

Dielectric heating

Different materials behave differently when exposed to microwave radiation
1.Transparent
2.Adsorbent
3. Reflective

These differences can induce intergranular fractures

Question 17

Draw an hydrocyclone and outline the main components.

Answer 17

Question 18

Explain of hydrocyclone work in 3 points.

Answer 18

1. large particles are pushed to the walls by the centrifugal force
2. The drag force brings the fine particles toward the centre of the hydrocyclone
3. The rotation of the mineral slurry creates a pressure drop towards the centre, dragging air inà
4. The water, and fine particles, spiral upwards around the central air core to be recovered as overflow
5. The larger particles exit at the bottom, recovered as the underflow

Question 19

Draw a partition curve

Answer 19

Question 20

Give the partition number formula.

Answer 20