Hot mix asphalt production

HMA made continuously and sent to storage silosDrying and mixing drum Bitumen Tanks Filter Baghouse Hot Storage Bins Exhaus t Fan... TWIN DRUM PLANT : FLOW... COUNTER-RAP FeedAggregate f

Chris Lange PMP, Pr.Tech.(Eng)

Director (Technical)

Much Asphalt (Pty) Ltd

Road Pavement Forum: 10 th April 2006

 Plant types and basic components

 Plant calibration

 Dust extraction

 Filler handling and control

 Aggregate heating

 Procurement / handling of raw materials

 Finished product storage

 Delivery

HMA made continuously and sent to storage silos

Drying and mixing drum

Bitumen Tanks

Filter Baghouse

Hot Storage Bins

Exhaus

t Fan

TWIN DRUM PLANT : FLOW

COUNTER-RAP Feed

Aggregate feed

Drying &

heating Drum

Coating &

mixing drum Finished

product

storage

Plant filler storage and feed

Filter Baghouse

Parallel-Flow

Drum-mixer Zones

Combustion

Heating Drying Air

BIT Hot Mix

Asphalt Mixing

Counter-Flow mixer Zones

Drum-Aggregate Air

Counter-Flow Batch Plant Dryer Zones

Hot Aggregate

Combustion Heating Drying

Aggregate Air

Batch Plant Elements

Cold feed bins

Dr ye

r

Dr u m

RAP Feed

Hot mix asphalt dispensed into truck / hot-bin

Aggregate

from dryer

Aggregate to screens

Screens size aggregate

Bitumen Weigh- hopper

Aggregate and bitumen

weigh hoppers

Warren Brothers Patent

Application Drawing: Original

Batch Plant

Cold feed system

Belt scale Reference

scale

Cold Feed Bins and RAP Bin

Induced Air Burner

In-line heater HFO Sampling

pt HFO

Tank

Temperature Profile of Counter-Flow Dryer

400º C

800º C

Drum Flights / Lifters

Exhaust Fan

Filtered Air

Fines collected and returned

Outlet tube

Spin vanes

Inlet tube

Valve

Collector element Gas inlet

Gas flow

Air

Optional knock down plate

Bitumen

Fines mix with hot mix asphalt

Dust screw Dust screw

Automatic Damper Controls

Batch tower

Hot Elevator

Cyclone

feeding fines

directly back

 Remove particulate matter

– Primary

– Secondary

 Return fines to the mix

– Affects void content

– Affects mix stiffness

– Difficult to control

BITUMEN TANKS – ELECTRICALLY HEATED/

24 HR TEMPERATURE MONITOR AND

CONTROL

Plant Automation – Operating System Graphics

Binder Content

Voids in Mix

Filler Content

Plant

Mixing

Tower

Skip Bucke t

Winc h

The End