Production of Aggregate

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CHAPTER

Construction Planning, Equipment, and Methods

Sixth Edition

AGGREGATE PRODUCTION
• A. J. Clark School of Engineering •Department of Civil and Environmental Engineering

14

By Dr. Ibrahim Assakkaf ENCE 420 – Construction Equipment and Methods Spring 2003 Department of Civil and Environmental Engineering University of Maryland, College Park

CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 1
ENCE 420 ©Assakkaf

PRODUCTION OF CRUSHEDSTONE AGGREGATE
The production of crushed-stone aggregate involves:
Drilling Blasting Loading Transporting Crushing Screening Product handling and storage

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CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 2
ENCE 420 ©Assakkaf

PRODUCTION OF CRUSHEDSTONE AGGREGATE

In operating a quarry and crushing plant, the drilling pattern, the amount of explosives, the size shovel or loader used to load the stone, and the size of the primary crusher should be coordinated to assure that all stone from the quarry can be economically utilized.

CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 3
ENCE 420 ©Assakkaf

RECOMMENDED MINIMUM SIZES OF PRIMARY CRUSHERS
Table 1

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CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 4
ENCE 420 ©Assakkaf

TYPES OF CRUSHERS

Crushers are classified according to the stage of crushing which they accomplish, such as: Primary Secondary Tertiary

A primary crusher receives the stone directly from a quarry after blasting, and produces the first reduction in size.

CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 5
ENCE 420 ©Assakkaf

TYPES OF CRUSHERS

The output of the primary crusher is fed to a secondary crusher, which further reduces the stone size. Some of the stone may pass through four or more crushers before it is reduced to the desired size. The degree of breakage is spread over several stages as a means of closely controlling product size and limiting waste material.

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CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 6
ENCE 420 ©Assakkaf

TYPES OF CRUSHERS

As stone passes through a crusher, the reduction in size may be expressed as reduction ratio. The reduction ratio is the ratio of crusher feed size to product size. The sizes are usually defined as the 80% passing size of the cumulative size distribution. For jaw crusher, the ratio can be estimated by the gape.

CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 7
ENCE 420 ©Assakkaf

TYPES OF CRUSHERS

The gape is the distance between the fixed and moving faces at the top, divided by the distance of the open-side setting at the bottom. The reduction ratio of a roller crusher can be estimated as the ratio of the dimension of the largest stone that can be nipped by the roller, divided by the setting of the rolls, which is the smallest distance between the faces of the rolls.

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CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 8
ENCE 420 ©Assakkaf

TYPES OF CRUSHERS

Crushers are also classified by their method of mechanically transmitted fracturing energy to the rock. Jaw, gyratory, and roll crushers work by applying compressive force. Impact crushers such as single rotor and hammer mill apply high-speed impact force to accomplish fracturing Table 2 (T 14-2, Text) lists the major types of crushers.

CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 9
ENCE 420 ©Assakkaf

MAJOR TYPES OF CRUSHERS
Table 2

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CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 10
ENCE 420 ©Assakkaf

JAW CRUSHERS

Jaw crushers operate by allowing stone to flow into the space between two jaws, one of which is stationary while the other is movable . The distance between the jaws diminishes as the stone travels downward under the effect of gravity and the motion of the movable jaw, until the stone ultimately passes through the lower opening.

CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 11
ENCE 420 ©Assakkaf

JAW CRUSHERS

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CHAPTER 14. AGGREGATE PRODUCTION

Slide No. 12
ENCE 420 ©Assakkaf

JAW CRUSHERS

Jaw crushers are usually designed with the toggle...
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