Asphalt Batch Plant Operation and Components
The main composition and operation of the asphalt batch mixing plant. It is the production of HMA, called asphalt mixing plant and hot mixing plant. It mixes aggregate and asphalt to produce hot mixed paving materials. Aggregates here can be single-sized materials. It can be a combination of different grades/sizes of materials. Finer aggregates are also added along with mineral fillers. The binding material, also known as asphalt cement, can be cutback bitumen, synthetic binder, or emulsion.
The operation of the asphalt batch mixing plant begins with feeding the aggregate into the feed bin. The operation ends when the hot mix asphalt is unloaded into the truck.
- The first step is to feed unheated raw aggregate into different bins of the cold aggregate feeder. This feeding must be based on their size. Each bin has a cold feed door to control aggregate flow.
- The aggregate is then transferred to a drying drum. The loading conveyor transfers the aggregate to the drum.
- The drying drum is equipped with a burner. The burners efficiently heat-dry the aggregate.
- Most hot mix plants are equipped with a primary dust collector. It is used to settle heavy dust particles.
- Primary dust collectors work best with secondary dust collectors. The secondary dust collector is a bag filter.
- Once the aggregates have finished heating in the drum, they are transferred to the tower unit. Bucket elevators are used to transfer the aggregate.
- On top of the tower unit, we have the screening unit. It is multi-layered. As the hot aggregates pass through the screen, they are processed to achieve a sieving effect. They will be separated and stored in different boxes according to their size.
- There are separate hot litter boxes there. This help to store each type of aggregation separately.
- Then weigh the aggregate. After weighing, these aggregates will be discharged into the mixing device. In the mixer, the aggregate will be mixed with the bitumen and filler.
- Bitumen tanks heat and store bitumen. It is equipped with a pumping station. Bitumen is pumped into a weigh hopper before discharge. This bucket weighs it before adding it to the blender. Fill material is added to a separate container and pumped into a weighing hopper. Only after the fill material has been weighed it is discharged into the mixing unit.
- After a fixed time of mixing, the hot mix asphalt is ready to be unloaded into waiting trucks. In some cases, it is transferred to storage silos for temporary storage.
- The control panel is used to use/control the device.
Asphalt Batch Mix Plant Process:
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.
Asphalt Mixing Plant Components:
The components of an asphalt mixing plant ensure the smooth operation of the plant. All parts have to work in perfect sync. All types of asphalt equipment may have different components. But their purpose is to produce hot mix asphalt according to the required recipe.
The Following Are the Components of an Asphalt Plant
Cold aggregate silo
Primary vibrating screen
Loading conveyor
Drying tumbler with multi-fuel burner
Hot aggregate bucket elevator
Pre-separator with bag filter
Multi-layer vibrating screen
Hot storage
Stirring device
Bitumen storage and transfer tanks
Weighing hoppers for aggregate, bitumen, and filler material
Fill storage silos/hoppers
Control room and panel
Bitumen storage silos
Cold or hot RAP hopper
What Are the Common Operations of Asphalt Mixing Plants?
Common operations in an asphalt mixing plant include heating aggregates and mixing them with bitumen and binder materials. These processes can be carried out in a simple way with continuous plants or in a complex but more precise way with batch plants.
What Are the Asphalt Batch Mixers of D&G MACHINERY?
Batch Type Asphalt Mixing Plant: PM batch asphalt mixing plants have a complete product lineup, including stationary, mobile asphalt batch mixing plants and continuous drum mixing plants. Thanks to its compact design, it can fit into some small spaces with full functionality. Precise control systems, quick response initiatives,s, and stable quality can satisfy almost all customers' needs in a more economical way. It is designed and manufactured according to European quality standards and is CE and EAC certified. The unit adopts first-class components to ensure stable operation and long service life.
SOC Batch Asphalt Mixing Plant: The DG Compact range is specially designed for sea freight export boxes. The mixing tower and bag house and control room are designed in Shipper's Own Container (SOC) mode, which greatly saves transportation costs. In addition to being easy to transport, it maintains the same high-end production performance and component selection as the D&G standard range.
RAP Batch Asphalt Mixing Plant: DGX series products are a "deformable combination" asphalt mixing plant innovatively developed by D&G MACHINERY in 2020 according to the diversified needs of customers and the market. In addition to the advantages of "one machine with multiple types and on-demand combination", the idea of cross-model planning and design is adopted, and each functional module is combined according to different modes to realize the conversion of different equipment styles and functions, and to meet the needs of different production conditions. According to the different requirements of customers, modularization can be adjusted in various ways according to customer needs, and the completion efficiency is extremely high.
Recently, a D&G MACHINERY DGXR4500 asphalt mixing plant located in Zhanjiang, Guangdong has been put into the production of recycled materials. The engineers of D&G MACHINERY also came to the scene early to escort the efficient and stable operation of the equipment! DGXR4500 has the advantages of "one machine, multiple types, the on-demand combination" of DGX series products, which can not only fully meet the local complex and changeable environmental needs, but also meet the local environmental protection requirements. Environmental protection measures such as factory building design closed feeding channels, and independent asphalt fume collection and treatment equipment minimize dust, noise, and asphalt fume pollution.
Asphalt batch mix plants are the most widely used type of asphalt plants. Asphalt batch mix plants produce high-quality asphalt mixture for all grades of road pavement /rehabilitation and all sizes of asphalt production. D&G MACHINERY manufactures several types of asphalt batch mix plants with capacities from 105-400t/h, including Modular Series, Containerised Series, Transformable Series, and RAP Series. Furthermore, they can be tailored to clients' special requirements. If you still have questions or want to buy an asphalt mixing plant, please contact us.
