Giving New Life to Old Equipment: Green and Intelligent Recycling Practice for Asphalt Mixing Plants
In today’s world where environmental requirements are becoming increasingly strict and raw material costs continue to rise, retrofitting existing asphalt mixing plants with recycling functions has become an essential strategy for plant owners to cut costs, improve efficiency, and enhance competitiveness. A customer in Tianjin, China, demonstrating remarkable foresight, successfully upgraded their 3000-model asphalt mixing plant with D&G Machinery’s add-on recycling system, along with our efficient RAP (Reclaimed Asphalt Pavement) crushing and screening equipment. The project, with an RAP addition rate of 50%, has been producing high-quality reclaimed asphalt mixtures, setting a benchmark in the region.
Project Background: Old Plant Facing New Challenges, Urgent Need for Cost-saving
The customer’s existing asphalt mixing plant was conventional. Faced with a large inventory of RAP and increasing costs of bitumen and aggregates, the customer was determined to retrofit the plant with recycling capabilities.
After extensive research and technical comparisons, the customer finally chose D&G Machinery —a company renowned for its expertise in asphalt recycling technology—as the service provider for the project.
Key Highlights: How D&G Machinery’s Recycling Retrofit Turns "Stone into Gold"
D&G Machinery provided the client with a customized solution, which is not a simple "patch-up" but a systematic upgrade throughout the whole process, including RAP drying and heating, buffering and weighing, as well as RAP flue gas treatment. Its core technological highlights have been fully validated in this practical application:
Highlight 1: The New-generation “Self-cleaning” Dryer Drum Ensures No-sticking Discharge
Innovative Structural Design:
It facilitates the formation of a more uniform material curtain, enabling the recycled materials to be heated more evenly, thus enhancing overall thermal efficiency.
Less Maintenance Costs:
The "self-cleaning" modular design extends the drum cleaning cycle by 3 to 5 times, with a maximum cleaning cycle of once a year.
Controllable Discharge Temperature:
The discharge temperature of the recycled materials can reach up to 170℃, and the temperature of the counterflow heating exhaust gas can be maintained within just 10°C above the discharge temperature.
Highlight 2: Intelligent Control System & Eco-Friendly Design, "One-Button" Smart Production.
Easy Operation: The upgraded system features a streamlined workflow, which is easy to operate with less errors.
Asphalt Fume Treatment: Equipped with an efficient flue gas treatment system for the RAP dryer drum, the RAP asphalt fumes are directed into the main drum for second combustion before entering the bag filter. This ensures emissions comply with environmental standards, enabling green production.
Foundational Support: High-Efficiency RAP Crushing & Screening Equipment as a Critical Component.
Even the most advanced recycling system relies on the stable supply of high-quality, well-graded RAP. The customer’s D&G RAP crushing and screening plant, with a capacity of 100 t/h, serves as the solid foundation for the entire recycling system. Its key advantages are also impressive:
Flexible Crushing, Stable Degradation:
Designed specifically for the unique properties of milled asphalt pavement, the plant is equipped with an asymmetric toother roller crusher with low-speed, flexible crushing technology to apply shearing, squeezing and bending on the RAP. The two opposing roller heads are arranged horizontally (featuring a height difference). Compared to ordinary toothed roll crushers, this design increases the meshing area of the crushing teeth, enabling the passing of large clumps of recycled materials. While retaining the key advantages of toothed roller crushing, this design minimizes impact on the material, thereby reducing dust emissions, better preserving the original aggregate gradation, and minimizing the generation of fine particles.
Intelligent Automated Control:
RAP is fed by a wheel loader, and the entire operation can be managed by a single operator during production. The system features cloud-based data storage and supports remote intelligent diagnosis.
Multi-Layer Safety Protection:
The system includes multi-level interlock protections to ensure stable operation, unaffected by magnetic materials commonly found in RAP. When encountering uncrushable hard objects, the two rollers will automatically attempt up to three consecutive forward-and-reverse rotations to clear the obstruction. If clearance fails, the system will trigger an emergency shutdown, prompting operator intervention for inspection.
Customer’s Praise
"When we chose D&G Machinery for the equipment upgrade, what impressed us most was their technical expertise and hands-on experience in asphalt recycling. The results proved that our decision was right. The upgraded equipment is easy to operate, runs stably, and consistently delivers high-quality recycled asphalt mixture with a high RAP addition rate, bringing economic benefits. The complementary crushing and screening equipment also played a key role. It has become an indispensable part of our production chain, guaranteeing the quality of the RAP.”