The process of the asphalt batch mixing plant is explained in detail below. This equipment produces hot mix asphalt in batches. Each batch is a specific ratio of each item we need to mix.
Feed Cold Aggregate:
This is the first step. Aggregates of different sizes are fed into different feed bins. This helps to get the proper ratio of each size as needed. Each bin has individual gear and variable-speed drive motors. The speed of each bin can be controlled to get the proper ratio for each item.
Drying Drum Aggregate Heating:
A drying drum is one of the important components of asphalt equipment. It is equipped with burner units on one side of the rotating drum. The drums are sloped to allow the material to flow freely from one end to the other. The aggregates are transferred to drying drums after passing through the primary screening unit. Once in the dryer, the high temperature inside the dryer will help remove moisture from the aggregate. The burner unit plays an important role here. The lifting mechanism of the blades of the drying drum makes the aggregate heated evenly.
Bucket Elevators for Conveying Aggregates:
Once the aggregates leave the drying drum, they enter the bucket elevator. A bucket elevator is a long, covered structure that extends to the top of a tower unit. At the top of the tower unit, there are vibrating screens. Bucket elevators have many buckets connected by chains. This elevator unit transports the heated aggregates to the top of the tower and helps them enter the top of the vibrating screen unit.
Hot Aggregate Screening:
On top of the tower unit, there is the shaker unit. The screening unit is a multi-layer full coverage unit. Screens of different sizes are arranged one after the other. As the aggregates fall on top of the first layer of the screen, they are processed into a vibrating effect. This vibrating effect will help transfer material from one screen to another. As they pass from one screen to another, oversized materials are removed as they will not pass through the uppermost screen.
Hot Bins:
After the screening, all materials will be separated and stored in different compartments. These compartments are called thermal compartments. They will store the aggregate and help weigh it before it is discharged to the mixing unit.
Asphalt and Filler Weighing Mechanism:
Bitumen and mineral fillers are weighed before being discharged into the mixing unit. There is a round and insulated bitumen-weighing hopper that can store a certain amount of bitumen. This hopper will weigh the required amount of bitumen and discharge it into the mixing unit. The filler hopper holds and weighs the filler before discharging it into the mixer.
Hybrid Unit:
The mixing unit receives the aggregate from the weighing hopper transferred from the hot bin. It also receives bitumen from the weigh hopper delivered by the bitumen tank. The filler is also discharged from the filler-weighing hopper. If RAP is added, weigh it before draining it into the mixing unit. The mixing unit thoroughly mixes all contents for a fixed time before unloading the contents into a truck or storage silo. There are two horizontal axes on which the arms and tips are mounted. These arms and tips will rotate on an axis and are used to mix the materials inside the mixer. The mixer is jacketed so that the contents inside remain hot.
Bitumen Storage and Transfer Tanks:
Bitumen tanks serve as storage points for bitumen used in bitumen plants. Bitumen tanks are available with direct or indirect heating. Directly heated bitumen tanks will be equipped with a burner for heating the bitumen. The flame from the burner is directed into a tube that will transfer heat inside the tube to melt the bitumen. The coils of the indirect heating system run inside the asphalt tank. These coils will continuously circulate hot oil through the coils, which in turn will heat the bitumen. Bitumen tanks are available in different sizes according to customer requirements.
Filler Storage:
Mineral fillers are an integral part of asphalt batch mixing plants. It will store the filler and then transfer it to the filler weighing hopper by screw conveyor. The size of the filler storage can be varied according to customer requirements.
Bag Filter Unit for Pollution Control:
A bag filter and pre-separator are two important units for trapping harmful gas and dust particles. A pre-separator will capture all heavy dust. A baghouse is a closed chamber with many bags next to each other. As the air sucked in from the drying drum passes through the bag, they will be trapped. This action of the baghouse will help to remove most of the pollutants and emit a less polluted fume.
Control Panel:
The control panel is the control unit of the asphalt mixing plant. Operators can control all plant operations from the control panel. Intelligent control system provided by D&G MACHINERY, the system is configured with Siemens PLC, and it has 2 wiring configuration options: PROFI bus and distributed control system. Both modes can ensure real-time signal feedback without lag.