Aggregate grinding

EQUIPMENT FOR

PRODUCTION OF

AGGREGATE

AGGREGATE

Crusher Feeder Screening Handling

CRUSHED-STONE AGGREGATEAND

STONE CRUSHERS

A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust.

CLASSIFICATION

Primary Crusher Secondary Crusher Tertiary Crusher

TYPER OF CRUSHER

Jaw Gyratory Hammer Mill Cone Impact

JAW CRUSHER

It consist of set of vertical jaw• Fixed jaw• Movable jaw

Movable jaw which moves back and forth relatively

Manganese steel

Single and double toggle jaw crushers are constructed of heavy duty.

high strength design to accept high power draw

Double Toggle jaw crushers, hydraulic toggle adjusting mechanisms.

JAW CRUSHER

GYRATORY CRUSHER

consisting of a concave surface and a conical head; both surfaces are typically lined with manganese steel.

the movement is generated by an eccentric arrangement

used for primary or secondary 

It is designed in size either by the gape and mantle diameter or by the size of the receiving opening.

ILLUSTRATION

short-shaft suspended spindle typemain shaft is suspended at the top

and that the eccentric is mounted above the gear

long-shaft suspended spindle typemain shaft is suspended at the top

and that the eccentric is mounted below the gear

HAMMER MILL

It is other wise called GRINDING MILL

Earlier functionHandAnimalWaterwind

PURPOSES IN ENGINEERING

Following:increase of the surface area of a solidmanufacturing of a solid with a desired

grain sizepulping of resources

GRINDING LAWS

KICK for d > 50 mm

BOND for 50 mm > d > 0.05 mm

RITTINGER for d < 0.05 mm

To calculate the grinding work against the grain size

W = grinding work in kJ/kg,  c = grinding coefficient,  dA = grain size of the source material dE = grain size of the ground material. A reliable value for the grain sizes dA and dE is d80. Value signifies that 80% (mass) of the solid matter has

a smaller grain size.

With the limits of Bond's range: upper dBU = 50 mm and lower dBL = 0.05 mm

To calculate the KICK's and RITTINGER's coefficients 

GRIDING DEGREE Grinding degree referring to grain size d80

Instead of the value of d80 also d50 or other grain

diameter can be used. Grinding degree referring to specific surface

The specific surface area referring to volume Sv and

the specific surface area referring to mass Sm can be found out through experiments.

Pretended grinding degree The discharge die gap a of the grinding machine is

used for the ground solid matter in this formula.

TYPES OF GRINDING MILL

Ball Mill Rod Mill SAG Mill Autogenous Mill Pebble Mill Buhrstone Mill

CONE CRUSHER

similar in operation to a gyratory crusher

with less steepness in the crushing chamber

more of a parallel zone between crushing zones

suitable for crushing varies of mid-hard and above mid-hard ores and rocks

ADVANTAGES

Most reliable construction High productivity Easy adjustment Less cost in operation

IMPACT CRUSHER

Involve the use of impact rather than pressure to crush material

usually used with soft and non-abrasive material such as coal, seeds, limestone, gypsum or soft metallic ores

TYPES OF IMPACT CRUSHER

Horizontal shaft impactor

Vertical shaft impactor

HORIZONTAL SHAFT IMPACTOR

It is fixed upon the outer edge of a spinning rotor.

use of HSI crushers is limited to soft materials and non abrasive materials, such as limestone, phosphate, gypsum, weathered shale's

to crush a mile (or 1.6 km) windrow of material in a single day.

VERTICAL SHAFT IMPACTOR

VSI crushers use a different approach involving a high speed rotor with wear resistant tips and a crushing chamber designed to 'throw' the rock against

CONTROLLED

the velocity at which the rock is thrown against the anvil.

the distance between the end of the rotor and the impact point on the anvil.

FEEDER

It help mainly in handling the input material for the plant

They are two typeApron feederMechanical or reciprocating plate

feeder

APRON FEEDER

It is an heavy-duty construction to take shock from racks dumped directly on them

It consist of a series of overlapping pans.

Widths of feeder range from 01-15ft & lenghts vary from 01-0f times of width.

FORMULA

hourtonsDW

q /4800

Where,q = capacity of the feeder, W = tray width, inD = material depth, in = density of the material, lb/cu ft = material flow velocity, ft/min

The flow velocity depends on the method for loading the feeder – is it fed through a hopper

The velocity is also dependent on the material characteristics, size distribution and moisture content, as well as the slope of the feeder.

The only way to determine the value for is by actual observation and then the feeding rate may vary considerably.

An even flow of material to the primary crusher. The size of the feeder and its speed should

provide a capacity 25-35% greater than the capacity to regulate the feeder in the case of irregular dumping of the raw material.

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