HOT MIX ASPHALT PRODUTION

Road Pavement Forum: 10th April 2006
Chris Lange PMP, Pr.Tech.(Eng)
Director (Technical)
Much Asphalt (Pty) Ltd


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Plant types and basic components
Plant calibration
Dust extraction
Filler handling and control
Aggregate heating
Procurement / handling of raw materials
Finished product storage
Delivery


Exhaust
Fan

Filter
Baghouse

Primary
dust
collector

Hot
Storage
Bins

HMA made
continuously
and sent to
storage silos

Bitumen
Tanks
Scalping screen to
remove oversize
aggregate
Belt scale

Drying and mixing
drum
Cold Feed Bins


TWIN DRUM PLANT : COUNTER-FLOW

RAP Feed

Plant filler
storage and
feed
Filter
Baghouse

Finished
product
storage

Coating &
mixing
drum

Aggregate
feed

Drying &
heating Drum


Parallel-Flow Drummixer Zones
Air

Combustion

Heating

Drying

Mixing

BIT.
Hot Mix
Asphalt


Counter-Flow Drummixer Zones

Air

Mixing Combustion Heating

Hot Mix
Asphalt

Bitumen

Drying

Aggregate


Counter-Flow Batch
Plant Dryer Zones

Combustion Heating

Drying

Air
Aggregate

Hot Aggregate


Batch Plant Elements
Primary
Filter Baghouse collector

Batch/Mixing tower

Hot Storage
silos
Bitumen
storage
tanks

r
e
y
Dr um
Dr

Cold feed bins

RAP Feed

Aggregate to screens
Screens size
aggregate

Hot aggregate
travels up bucket
elevator

Aggregate
weigh hopper
Pugmill
Aggregate
from dryer

Bitumen
weigh
pot
Hot mix
asphalt
dispensed
into truck /
hot-bin


Aggregate and bitumen weigh
hoppers

Bitumen
Weighhopper

Warren Brothers Patent Application
Drawing: Original Batch Plant


Cold feed system

le
a
c
s
Belt
Reference
scale


Cold Feed Bins and RAP Bin


Tons per Hour

Feeder #1
80
70
60
50
40
30

20
10
0
20

50

90

Belt Speed or Potentiometer Setting






Induced Air Burner


HFO
Tank

In-line heater

HFO Sampling pt


Temperature Profile of
Counter-Flow Dryer
Combustion

Drying

Heating

800º C
760º C

120º C

Gas
es

400º C

Aggregates

0º C

150º C
300º F

150º C

Aggregate

100º C

20º C