Lecture 1

Prof.Dr.Salah ElmoftyPh.D.professor

Material TechnologyDepartmentofMiningPetroleum&Metallurgical,

Faculty Of Engineering

E-mail:[email protected]

Lecture:1

Comminution

Comminution

-Ore minerals are usually finely disseminated and intimately associated with gangue minerals.

-These minerals should be liberated before concentration.

-This liberation accomplished by comminution.

-Communiation is one of the primary operations in mineral dressing

ComminutionComminution

CrushingCrushing GrindingGrinding

Crushing

Feed size ranging from 3” to 30” can easily be handLed

The feedsize in all this cases varies

from 1.5” to 6”

Primary Secondary crushing crushing

Jaw crushers & Gyratory crushersCone crusher

& Roll crusher

Blake crushers

These crushers built in many sizes

-The largest boluldr is 4 feet in diameter

-SmallestTakes feed around 3 to 4 inches

Primary crushers

Jaw crushers Gyartory crusher

Blake crushers

Constraction:

Liners:

-The material used for lining the

jaw plates and check plates.

Jaw crushers:

Characteristics of jaw crushers:

1-They are working little than half the time.

2-Because of heavy flywheel and high speed of rotation they are favourable to more efficient action of jaw crushers.

3 -Rate of oscillation of the moving crushing surface determines the machine capacity

ordinary taper 4.5 per foot

4-Have less capacity than gyratory crushers

5-Work in open circuit with double deck screen

Gyratory crushers

Characteristics of gyratory:

1-Capacity is greater than jaw crushers.

2-Required power less than jaw. crushers.

3-There is less vibration in operating .

Wich of the two following crushers we should choose for small

capacity? & why?

Gyartory crusher Jaw crusher or

Jaw crusher is the better choice because of:

1-Jaw crusher can take larger size than gyratory &is better adopted to handle clayey &spongy rocks.

2-Gyartory crusher consume more power for the same feed as produces more new surfaces than jaw crusher..

3-Installation and housing costs will be more compared to jaw crushers.

Secondary crushers

Cone crusher Roll crusher

Cone crushers1-Cone crusher is secondary crusher.

2-Product of cone crusher is the feed of grinding mill.

3-It work in closed circuit with double deck screen.

4-Product is more uniform in size.

Cone crushers

Merits of cone crusher over gyratory

1-Cone crusher moves faster than gyratory .

2-Rapid discharge of crushed material due to increase space from top to

bottom .

3-Hier capacity and reduction ratio than gyartory crushers.

4-Work in closed circuit.

Roll crusher

Roll crusher

1-Used for crushing relatively soft materials like coal & salt.

2-Capacity is high and reduction ratio is large.

3-Can not produce fine product owing to the spacing between adjacent teeth.

Angie of nip

.

N

E

aaC D

C,D Rolls

E sphere of rocks

N angle of nip

Comparison between roll & cone crushers:

1-Roll crusher production smaller of fines than cone crushers and smaller reduction ratio.

2-Rolls,because of theirinability to yield ahigh reduction ratio,have not been installed in recent years.

3-Reduction ratio for rolls should not exceed

4:1 similar to cone crushers.

4-Rolls remain to be the best device for intermediate crushing.

THANK YOUTHANK YOUTha

nk yo

u

Thank

you

Prep

ared

by

Prep

ared

by::

Prof

. Dr.

SALAH

ELMOFTY