Drum Mix Plant Processes
The flow of materials (from left to right):
* Cold bins:
---> aggregates moved from the stock-pile area to the cold feed bins via a front end loader
---> The minimum required number of bins depends on the number of different ggregates to be used in the bituminous mixture. Most facilities have a minimum of 4 cold feed bins.
---> The metal cold feed bins have slanted sides with a vibrator attached (if gravity feed is inadequate) to keep a constant
supply of material flowing out of the bottom of the cold feed
---> Typically an adjustable gate and a variable speed feeder are located at the bottom of each cold feed bin to proportion the material from each bin to meet the job mix formula gradation.
* A gathering conveyor brings the material to the cold feed elevator which moves the material to the dryer. An automatic weighing system on this elevator continuously weighs the amount of aggregate plus moisture going into the drum mixer.
* In the control room, a correction to the total weight is made for the moisture content of the aggregates so that the the proper amount of bitumen can be pumped into the drum mixer.
* A typical drum mixer is of a parallel flow design in which the aggregates move in the same direction as (parallel to) the exhaust gases.
* Therefore, the aggregate is fed into the drum at the burner end and then it is dried and heated as it moves down the drum toward the discharge end.
* The bitumen is pumped from the bitumen storage tank and enters the drum at a point about one third the drum length from the discharge end.
* When the bitumen is added into the drum, it is pumped into the bottom of the drum at about the same location that the mineral filler and/or baghouse fines are reintroduced. Adding bitumen and dust in close proximity allows the bitumen to trap the fines and to coat them before they are picked up by the high velocity exhaust gas stream.
* The bitumen coats the aggregates as the materials move down the lower third of the drum.
* The bituminous mixture exits the drum through a discharge chute into a conveyor system which transports the mixture into a surge silo from which it is discharged into trucks via an automatic scale system.
* It is then transported to the site.
All material movements from the cold feed to the surge sile are monitored from the control room. Sensors at various locations in the facility monitor conveyor speeds, aggregate weights, temperature, and other critical functions which affect efficient operation.
Title Post: Drum Mix Plant Processes
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Author: aditya
Rating: 100% based on 99998 ratings. 5 user reviews.
Author: aditya
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