What Are The Components of Asphalt Mixing Plant?

Asphalt mixing plant is the key equipment for producing asphalt mixture, mainly used for asphalt pavement paving in road construction. Asphalt mixing plant mixes aggregates of different particle sizes, fillers (such as mineral powder), and binders (such as asphalt) in a certain proportion. Asphalt mixing plant components and structure are complex, and each system works together to ensure the quality and efficiency of the mixture.

 

The following are the main components of asphalt mixing plant:

1. Cold material supply system
- Function: Store and accurately proportion aggregates of different particle sizes (crushed stone, sand, etc.).
- Composition:
Cold material bin: There are usually 3-6 independent bins for classified storage of aggregates of different specifications.
Feeding device: Control the flow of aggregates through vibrators or belt conveyors.
Aggregate conveyor: Collect and transport aggregates output from each cold material bin to the drying drum.
- Key points: The feeding speed needs to be adjusted according to the grading requirements to ensure the accurate proportion of aggregates.

2. Drying system
- Function: Remove moisture from aggregate and heat to 160-200℃.
- Core equipment:
Drying drum: Inclined rotating drum with blades inside to improve the uniformity of aggregate heating.
Burner: Uses diesel, heavy oil or natural gas as fuel to produce high-temperature flames.
Hot air system: Uses induced draft fan to guide hot air flow to countercurrent contact with aggregate to improve thermal efficiency.
- Features: Temperature needs to be controlled to prevent overburning of aggregate or residual moisture.

3. Hot material lifting system
- Function: Vertically transport heated aggregate to the vibrating screening system.
- Equipment:
Bucket elevator: High-temperature resistant chain or belt drive, equipped with dustproof seal design.
Anti-blocking device: Prevent hot materials from sticking during lifting.

4. Vibration screening system
- Function: Classify hot aggregate by particle size (such as 0-3mm, 3-6mm, 6-11mm, etc.).
- Composition:
Multi-layer vibrating screen: Separate aggregates through screens of different apertures.
Hot material bin: Aggregates after classification are temporarily stored in each hot material bin, waiting for weighing.
- Accuracy requirements: The screen needs to be cleaned regularly to prevent blockage and grading deviation.

5. Weighing system
- Function: Accurately measure aggregate, asphalt, mineral powder and additives.
- Classification:
Aggregate weighing: Use electronic scales or cumulative scales, and the error must be ≤±0.5%.
Asphalt weighing: Control the oil-stone ratio through a flow meter or weighing sensor.
Mineral powder weighing: Screw conveyor with weighing bucket to prevent powder agglomeration.
- Criticality: Directly affects the oil-stone ratio and mechanical properties of the mixture.

6. Mixing system
- Function: Evenly mix hot aggregate, asphalt and mineral powder.
- Type:
Intermittent (forced): Each batch is stirred independently (typical equipment such as "building-type" asphalt mixing plant).
Continuous: Aggregate and asphalt are continuously fed, suitable for large-scale production.
- Structure:
Mixing tank: Double-shaft paddle forced stirring, time is usually 30-45 seconds/batch.
Insulation design: Prevent heat loss from causing changes in asphalt viscosity.

7. Dust removal system
- Function: Treat dust and exhaust gas generated during drying, screening and mixing.
- Composition:
Primary dust removal (gravity/inertial dust removal): Remove large dust particles.
Secondary dust removal (bag filter): Filter PM2.5 and above particles, efficiency ≥99%.
- Chimney: Emissions meet the standards, some equipment is equipped with desulfurization and denitrification devices.
- Environmental requirements: must meet local emission standards (such as PM≤20mg/m³).

8. Asphalt supply system
- Function: store, heat and transport liquid asphalt.
- Equipment:
Asphalt storage tank: with insulation layer and heating coil (thermal oil or electric heating).
Asphalt pump: gear pump or screw pump, transport to mixing tank.
- Temperature control: Asphalt needs to be maintained at 150-170℃ (modified asphalt temperature is higher).

9. Finished material storage system
- Function: temporarily store finished asphalt mixture to avoid too fast temperature drop.
- Structure:
Finished product warehouse: insulation design, equipped with electric heating or gas heating device.
Unloading door: pneumatic or hydraulic control, fast unloading to transport vehicles.
- Capacity: Usually can store 100-300 tons of mixed materials.

10. Control system
- Function: Fully automatic monitoring of production process.
- Core:
PLC/industrial computer: preset formula, adjust parameters, record production data.
Sensor network: real-time monitoring of temperature, pressure, flow and other parameters.
Human-machine interface (HMI): touch screen operation, support fault diagnosis and alarm.
- Intelligent trend: Some equipment is equipped with AI algorithm to optimize energy consumption and grading.

11. Auxiliary system
- Mineral powder supply system: screw conveyor + storage tank, moisture-proof and anti-caking.
- Fuel system: fuel tank, booster pump and pipeline.
- Asphalt fume treatment: activated carbon adsorption or catalytic combustion device.

Classification and selection of asphalt mixing plant types:
- By process: intermittent (precisely control grading, suitable for high-grade roads) vs continuous (high efficiency, suitable for ordinary roads).
- By mobility: stationary asphalt mixing plant (large projects) vs mobile asphalt mixing plant (flexible transfer, small and medium-sized projects).

Asphalt mixing plants realize automated production from cold aggregate to finished products through multi-system collaboration. Their design must take into account efficiency, precision and environmental protection. Different configurations can be selected for different engineering requirements (such as highways and municipal roads). At the same time, key components (such as burners and bag filters) must be regularly maintained to ensure long-term stable operation.