Mumbai University > Civil Engineering > Sem 8 > Construction Engineering

Marks: 10Marks

Types of Crusher:

Jaw Crusher

Impact Crusher

Roller Crusher

Cone Crusher

Gyratory Crusher

Jaw Crushers

Jaws crush the stones by compression. The jaw crushers are used as either primary or secondary crushers but are considered best for primary crushing.

There are suitable where lesser fines are desired.

These crushers have two jaws – one is ‘fixed jaw’ & another is ‘swing jaw’

The ‘Swing Jaw’ are made of either manganese chrome- steel or heavy duty cast steel, annealed and stress relief to withstand the tough crushing operations.

The fixed jaws are made up of high manganese caststeel.

The capacity of crusher is influenced by the size of the product, nature and type of rock or ores i.e feeding materials.

Main Components:

Frame: It is constructed with heavy fabricated steel.

Hinge Pin and Jaw: A rigid steel hinge pin is champed the frame. The swing jaw assembly is fitted with long steel bearing to distribute the load evenly to hinge pin.

Jaw Plates: Crushing surface of jaw plates depends on the application; manganese chromium cast steel is used for the jaw plates.

Toggles: Toggle ends are precision machined, polished and hardened. This end moves in bronze toggle seats. A bronze toggle pin rests between the inner ends of toggle and pitman and entire assembly held together by hold back sping and by nest of littlesprings.

Jaw Adjustment for Product Size Control:

• Pitman.

  • Eccentric Shaft and Bearing.

  • Flywheels.

Impact Crusher

These are used where materials are too hard and abrasive and finished product requirement is for cubical shape well graded materials.

In this, stones are broken by means of impact and not by compression as in jaw Crusher.

In this stone is normally fed into the top of a breaker chamber and struck by rotating, hammers while it is in susf.

The hammers repeatedly throw the materials against breaker bars forming the roof of the breaker cha.

Impact crusher is fitted with one or two rotor and the hammers may be fixed or allowed to swing or pivots.

These are used for primary or secondary crushing.

Since impact is instantaneous, the breaking almost eliminates the possibility of development of hidden cracks in the product. The quality is important for aggregate product.

Advantages:

1. Lower Initial Cost.

2. Have fewer parts to maintain.

3. Wide range of product gradation can be selected.

4. These produces well guided cubical shaped products.

5. Types:

1) Impact Breakers

2) Hammer Mills.

Impact Breakers can crush even hard materials like basalt and granite.

Impact Breakers is a rugged and rigid machine, which is also provided with a safety devices to prevent damage to the rotor, etc.. in case of accidental overload.

Roll Crushers:

It is a reduction crusher and follows a primary breaker in the crushingcircuit.

It is suitable for all type of materials, whether it is a gravel, rock, limestone, or toughest one.

In these, the crushing members are 2 manganese steels, shells mounted over the two roll shafts which are further mounted on cast steel hubs.

Both the rolls are positively driven, rotating towards each other. These are supported on the antifriction rolls bearings.

The crusher can be adjusted to produce a wide range of sizes of materials by changing the discharge opening.

Advantages:

1) Maintenance is Simple.

2) It produces uniform material.

3) A change of shells on crusher rolls requires lesser fine.

4) For a given capacity, it is cheaper in initial cost and install.

5) It is economical for a given capacity and reductionratios.

6) Wide range of adjustment enables to conform strict specifications.

Types of Roll Crushers:

Both Roll Shell Smooth: These are used when producing material of 12mm and under. These are widely used in quarrying industries, mining, Chemical, Ceramic and metallurgical industries.

Double Toothed Roll Crushers: These are generally recommended for production of materials over 25mm, and too reduction of course soft and medium hard, non- abrasive materials like coals, cokes, slags, ore , limestone’s, etc.

One Smooth and One Corrugated Shell: These are used when producing material between 12 to 25mm size and for mate of medium hard qualities.

Corrugated Rolls: These can take bigger feed size than plan rolls of same diameter. Smaller the product, finer is the corrugation.

Spiked Roll Crusher: These are used for very high throughput capacity.These have one spiked roll and one adjusted jaw, and are used for course crushing of materials like chemical, coal, sinters, etc.

Cone Crusher:

Cone crushers are used to produce final product, since they can receive and crush smaller size of stones of ore and produce more fine aggregates.

These stones are fed through feed chute, evenly into the crushing chamber where they are crushed quickly and uniformly.

The stones from feed chute first, fall on distribution plate which helps in distributing the feeding materials in cone crushers.

The crushing surface n the clearance between the concave and mantle is made of wear resistant high grade manganese steel for heavy duty operation and reduced work.

The crusher head has a guratory, swinging motion so that the crushing is done by direct pressure.

This results in a cubic product. The swinging motion is produced by an eccentric sleeve rotating in bronze bushing.

Gyratory Crushers:

Like come crushers, these also crush the rocks by applying pressure to the rock boulders between a stationary surface and rotating curved surface.

The crushed materials are discharged by gravity.

This crusher provides much larger, crushing surface than that of jaw crusher and therefore has a much higher throughput capacity.

These are generally used for primary crushing because of larger reduction ratio

These are best suited for primary crushing:

Features:

Dust has little affect.

Long Liner Life.

Wear is uniform and adjustment is simple.

Hydraulic System Enables finger tip control of machine.