How Do Asphalt Plants Work

Asphalt plant is crucial for road construction, blending asphalt with minerals to create mixtures meeting specifications. This process involves several steps, including initial screening, drying, heating, metering, and mixing. It can ensure that the asphalt mixture produced is of excellent quality and performance. Knowing how an asphalt plant works is key to good road quality and efficient construction. Let’s explore how asphalt plant works together!

1. Cold Aggregate Handling And Screening Process

The cold aggregate handling and screening process is crucial in asphalt concrete production, impacting the final mix quality significantly. The following are the detailed steps of the process and the fist step about the question – how does an asphalt batch plant work.

• Loading And Conveying: Cold aggregates of different sizes (i.e. unheated gravel, sand, etc.) are loaded into an aggregate feeder using a loader. The aggregate feeder conveys cold aggregates to initiate the screening and processing process.
• Preliminary Grading: In the aggregate feeder, we should carry out the preliminary separation and grading work to ensure the efficiency of the subsequent treatment process.
• Intermediate Filtration: The preliminarily processed aggregate is fed through the aggregate belt to the intermediate filtration screen. During this process, oversized cold aggregates are screened out to guarantee only compliant aggregates advance to the next stage.
• Inclined Belt Feed: The compliant cold aggregate is then conveyed to the drying drum via an inclined belt feeder. The inclined belt feeder lifts the aggregate to the required height and advances the screening process during material transport.
• Drying And Cleaning: The drying drum heats, dries, and cleans the aggregate by circulating hot air to remove dust and impurities. Dust and humidity from drying are treated efficiently in the extraction system to meet environmental standards.

It’s crucial to oversee and control each processing stage at the asphalt plant machine to maintain the mix’s stability and quality. By following these steps, only quality cold aggregates can enter the mixing process, ensuring high-quality asphalt concrete.

2. Drying Drum Mixing

Drying drum heating mixing is a core part of asphalt concrete preparation, the main purpose of which is to remove moisture from the cold aggregate and preheat it to create conditions for the subsequent mixing and blending process. The basic principles and process of this step are described in detail below.

The Basic Principle Of Drying Drum Mixing

The drying drum is a rotating cylinder in which the aggregate is heated by high-temperature gases generated by a burner. The burner is usually fueled by diesel, natural gas, or heavy fuel oil, and the heat generated is used to heat the aggregate directly through a heat exchange process within the drum. The rotation of the drum allows the aggregate to be uniformly heated as it moves, and at the same time enables continuous mixing of the aggregate.

Heating And Mixing Process

Here is the heating and mixing process of the asphalt mixing plant in the following.

• Aggregate Input: Cold aggregates that meet the requirements are transported to the inlet of the drying drum via an inclined belt feeder.
• Drying and Heating: After the cold aggregate enters the drum, the combustion system starts to work. The high-temperature gas generated by the combustion flows inside the drum and comes into full contact with the aggregate to achieve heating and drying. During this process, the moisture of the aggregate is evaporated and impurities such as dust are removed from the surface of the aggregate.
• Flue gas treatment: The flue gas generated during the drying process (containing water vapor and dust) is introduced into the dust collector system. In the dust collector, dust and other particles are effectively captured and separated before the cleaned flue gases are discharged into the atmosphere to ensure compliance with environmental requirements.
• Output of Aggregate: The heated and dried hot aggregate is fed to the drum outlet as the drum rotates and flows into the hot aggregate elevator through the lower outlet.
• Further Screening and Storage of Aggregate: The Hot Aggregate Elevator lifts the heated aggregate to the vibratory screening system, where it is further screened according to size and sorted according to specifications, and stored in the Hot Aggregate Storage Silo, awaiting the next step in the proportioning and mixing process.

The whole drying drum heating and mixing process not only ensures the drying and preheating of the aggregates but also realizes the uniform heating and high-efficiency treatment of the aggregates through continuous rotation and hot air flow, which lays a good foundation for the production of high-quality asphalt concrete. It also lays the foundation for the lifting and screening of the hot aggregate in the next step.

3. Lifting and Screening of Hot Aggregate

The lifting and sieving of hot aggregates is a key stage in the asphalt concrete production process, following the heating and mixing step of the drying drum. The main purpose of this stage is to grade and store the heated and dried hot aggregate for subsequent accurate proportioning and mixing. This process is described in more detail below.

Hot Aggregate Elevation

• Elevator Principle: Hot aggregates are usually elevated using a bucket elevator. This type of lifting equipment picks up the aggregate through a series of ‘buckets’ fixed to a conveyor belt or chain, which move upwards in response to the movement of the belt or chain, ultimately conveying the aggregate to a specified height.
• Operating procedure: The hot aggregate from the drying drum is first fed into the bucket elevator. The closed conveying effectively prevents heat dissipation and the entry of impurities during the lifting process.

Screening Of Hot Aggregates

• Screening principle: Screening is usually carried out using a vibrating screen. The vibrating screen uses the vibration force caused by the electric motor to classify the aggregate on the screen surface according to size. Larger aggregates cannot pass through the screen holes, while smaller aggregates fall to the next layer or pass directly through the screen holes.
• Graded storage: Workers allocate the screened aggregates to different silos for storage according to their size. Each silo stores aggregates within a specific size range, allowing workers to proportion them accurately according to the design requirements while preparing concrete.

Role And Importance

• Quality Assurance: Through lifting and screening, it ensures that the temperature and particle size distribution of the aggregate meets the requirements for producing asphalt concrete, which helps to improve the overall quality of the finished product.
• Improve efficiency: Reasonable classification and storage of aggregates can greatly improve production efficiency and shorten the production cycle.
• Reduce energy consumption: Effective lifting and screening process also helps to reduce energy consumption, as it can avoid repeated processing of unqualified aggregates.
• Environmental protection: This reduces the environmental pollution, especially through the control of dust emissions and the rational use of thermal energy.

In conclusion, lifting and screening hot aggregates in asphalt production directly impact final product quality and production efficiency. By rationally designing and optimizing the process, the asphalt batching plant’s performance and competitiveness can greatly improve. Next is the measurement and proportioning of aggregate, mineral powder, and asphalt.

4. Measurement And Proportioning Of Aggregate, Mineral Powder, And Asphalt

In the process of asphalt concrete production, the accurate measurement and proportioning of aggregate, mineral powder, and asphalt is the key to making high-quality asphalt concrete. A sophisticated control system can achieve this process to ensure that each batch of concrete meets the design requirements. The following are the basic steps and principles of this process.

Precise Measurement System

• Aggregate metering: Load cells (scales) usually measure the weight of the aggregate. A feeding device (e.g., belt conveyor) transports the aggregate from the silo to the weigh scale, and a control system regulates the feed rate to achieve the exact weight required.
• Ore Measurement:Users employ a similar weighing method for measuring ore powders. Considering the nature of mineral powders, users may need a dust-proof feeding system to prevent loss and contamination.
• Bitumen metering: Due to its viscous nature, bitumen is usually measured either volumetrically or by mass. The mass metering method accurately measures bitumen in a heated liquid state for precise proportioning.

Proportioning Control

The control system sets the ratio of aggregate, mineral powder, and asphalt according to the design requirements. Modern asphalt batch mixing plant usually adopts a computer control system, which can automatically complete a series of processes such as measuring, proportioning, and mixing. The operator only needs to input the recipe parameters on the control panel, and the system can be automatic.

Mixing Process of All the Materials

Workers measure all the materials and then convey them to the mixer for mixing. They add aggregate first, followed by mineral powder, and finally asphalt. The mixing time varies according to the circumstances, but it is important to ensure that the mixture is homogeneous. Special additives or processes in warm mix asphalt lower asphalt temperature for eco-friendly, energy-efficient laying processes.

Importance of Measurement And Proportioning

Accurate measurement and proportioning is essential to ensure the performance of asphalt concrete. Incorrect proportioning not only affects the service life and safety of the road but can also lead to wasted resources and an additional burden on the environment. Accurate metering and efficient proportioning processes can significantly improve productivity and shorten construction periods while reducing costs.

In conclusion, accurate measurement and proportioning of aggregate, mineral powder, and asphalt is the core link in asphalt concrete production. It directly determines the quality and performance of concrete. Modern technology and strict management can effectively ensure the accuracy and efficiency of this process. What’s more, if you meet some debugs in your normal operation, you can see the common problems and solutions of asphalt mixing plant.

5. Mixing And Finished Product Processing

Mixing and finished product processing are two important links in the asphalt concrete production process, which directly affect the quality and performance of the final product. We will introduce the two links in detail.

Mixing Process and Key Factors in the Asphalt Batch Mix Plant

• Mixing principle: Mixing is the process of mixing measured aggregates, mineral powders, asphalt, and additives where necessary. For homogeneous asphalt concrete, forced mixers fully integrate components.
• Mixing Time: The correct mixing time is essential to ensure a homogeneous mixture. Too long or too short a mixing time may affect the quality of the mixture produced by the asphalt mixing and batching plant.
• Mixing Temperature: The mixing temperature is also very critical. Too high or too low a temperature can affect the flow of the asphalt and the properties of the final mixture.

Operation Steps about the Mixing Process

Firstly, add the aggregate, mineral powder, and asphalt successively to the mixer according to the set ratio. Then start mixing and adjust the mixing time according to the different types of asphalt concrete. Continuously monitor the mixing condition to ensure the homogeneity and quality of the mixture.

Finished Product Handling

• Storage: After mixing, store asphalt concrete properly to maintain quality before use. In some cases, operators can use insulated or heated silos for short-term storage.
• Transport: Insulated delivery vehicles usually transport asphalt concrete to maintain its temperature and fluidity. During transport, avoid delays and excessive vibration to prevent mixture delamination or asphalt-aggregate separation.
• Paving: Upon arrival at the construction site, workers will pave the asphalt concrete in a predetermined location. The paving operation should be smooth and continuous to ensure uniform distribution and thickness of the mixture.
• Compaction: After paving, compact the asphalt concrete to enhance density and bearing capacity. When compacting asphalt concrete, choose the right roller based on type and design requirements for effective compaction.
• Cooling: After compaction, let the asphalt concrete cool naturally to ambient temperature for final curing and strength. Avoid placing heavy loads on the new pavement during this period.

Mixing and finished product handling are critical steps to ensure the quality of asphalt concrete. By mixing well and treating the product right, concrete quality improves and road lifespan extends effectively. Therefore, strict management and control of these two links is very necessary in the whole production process. For more videos, please visit YouTube.

What Are The Types Of Asphalt Mixing Plants?

• ALQ Series Stationary Asphalt Mixing Plant AMP: The ALQ Series stationary asphalt plant is set up in one place for extended periods, efficiently producing large volumes of asphalt mix. It’s ideal for large-scale projects like highway construction, airport runways, infrastructure work, and municipal road projects.
• ALT Series Asphalt Drum Mixing Plant: ALT continuous drum asphalt mixing plants are crucial for road construction, working continuously to enhance efficiency and quality. They’re versatile, can handle varied asphalt mixtures, and be adjusted for specific project needs.
• ALYQ Series Mobile AMP Asphalt Mixing Plant: ALYQ Series mobile asphalt batching plants consist of modules on trailers and chassis for fast relocation and setup. Ideal for factories on long, narrow routes, these are perfect for shifting mixing stations quickly. The mobility of the mobile asphalt plant suits county highways, rural roads, and construction sites, enabling flexible movement.
• ALYJ Series Simple Batch Type Asphalt Plant: The ALYJ simple discontinuous asphalt plant is a mobile solution designed for small ane medium-sized road construction. It doesn’t have a mixing tower but still produces 10-80TPH of asphalt per hour. It’s compact, efficient, and cost-effective, making it perfect for on-the-go construction needs.

Choose Aimix Asphalt Mixing Plant, Choose The Future!

How do asphalt plants work? Up to now, we all know about it in detail. An asphalt batching plant’s workflow is a precise, automated working process. Every step, from raw material prep to final product output, directly affects asphalt mixture quality and productivity. By optimizing each step, the asphalt mixing plant can greatly enhance performance, delivering top-quality materials for cost-effective road construction. All in all, you can know how asphalt plants work now!

By choosing our asphalt mixing plant, you get a set of efficient, high-quality, and environmentally friendly production equipment. Besides, you can also get a strong partner and get more knowledges such as what is the working principle of asphalt plant? We will try our best to help you win markets, attract customers, and grow your business. Contact us today to start your journey to success!