W.J. & H. CROZIER

QUARRY OWNERS AND

CIVIL ENGINEERING CONTRACTORS

 

 

 

 

 

 

 

An aerial view of Outlack Quarry taken May 2001

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Asphalt Production
 

 

 

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Asphalt or Bitmac production could be best explained in the form of a Process Flow Diagram. See Below:

 

Production/Delivery programme/schedule
Flowchart: Process: Production/Delivery programme/schedule
Customer Order Requirements
Flowchart: Process: Customer Order Requirements

 

 

 

 

 

 

 

 

Aggregate
Flowchart: Process: Aggregate

Dryer
Flowchart: Process: Dryer

Bitumen
Flowchart: Process: Bitumen
Raw Materials
Flowchart: Process: Raw Materials

 

Limestone Filler
Flowchart: Process: Limestone Filler

 

Screens
Flowchart: Process: Screens

 

 

Weigh Hopper
Flowchart: Process: Weigh Hopper

 

Weigh Hopper
Flowchart: Process: Weigh Hopper

Weigh Hopper
Flowchart: Process: Weigh Hopper

 

Mixer
Flowchart: Process: Mixer

 

Lorry
Flowchart: Process: Lorry

 

 

 

 

Quarry Dust Filler
Flowchart: Process: Quarry Dust Filler

 

 

Key:        Required for Asphalt making process only

 

Materials are produced in the Quarry. Feed bins are filled with the appropriate material from the stockpiles. Bitumen is stored in large heated tanks capable of holding approximately thirty tonnes each and crushed limestone and quarry dust are held in separate storage tanks within the plant.

The plant operator selects the relevant mix recipe on the plant computer. Feed bins drop the required aggregate onto a conveyor belt which travels to the dryer. This is a large drum which revolves constantly with a burner controlled by the computer heating the aggregate to temperatures of up to 200°C depending on the mixture e.g. asphalt requires much more heat than bitmac does.

The aggregate then travels up on a bucket elevator to the screen housing where the aggregate is screened on what could be described as  large shaking sieves of different sizes. The different sized stones are then stored in their relevant sized hot storage bin above the mixer so that they maintain their temperature. Fine Quarry dust is extracted via a large fan and can be directly pumped to a  storage tank or extracted into a pool to settle and be collected at a later stage.

As the bitumen is stored at around 150°C it requires no additional heating and is pumped from the storage tanks along insulated pipes to a large weighing bucket. Different mixes can use different bitumen. Here at W.J. & H. Crozier's we use 160/220 Pen (stored between 100°C and 190°C and has a mixing temperature of around 140°C) for the mixing of bitmac and 70/100 Pen (stored between 110°C and 200°C with a mixing temperature of around 160°C) for asphalt.

The recipe determines how much of each material is weighed off by the computer in the weigh hopper and is then dropped into the mixer where a series of arms and paddles mix the materials together for 45 to 60 seconds in batches of up to 1.5 Tonnes. These batches are then expelled out of a chute directly into a waiting lorry below or stored in a heated storage bin with a capacity of up to 23 Tonne until needed.

The plant operator will carry out a number of checks on the plant and transport throughout the day primarily to see that the body of the lorry is clean before loading, the temperature of the bituminous mixture is adequate as well as the look and smell of the mixture (organoeleptic check). He will also maintain the plant so that production runs smoothly.

 

 

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Last modified: 10/20/05