How is Asphalt Production Done?

Asphalt Production

As the Asphalt production facilities close to work area, it produce and complete the work in short terms.
Asphalt plants are of three types. Batch plants, Drum mix (continuous mix) plants and Integrated asphalt plants. All three types can be produced as fixed and mobile .

1- Batch Type Asphalt Plant :

It is the most consumed plant type in the world. High-quality production can be done in this type of plant. After all the components, which are weighed separately depending on the desired properties in a production process, are added to the production process, each production period is completed in about 40-50 seconds. The amount of production in such plants is less than the drum mix plants.

2-Drum mix(Continuous Mix) Asphalt Plant:

Unlike batch plants, bitumen and other additives are added to it while the aggregate leaves the dryer. In this type of plant, since there is no mixer, waiting times that occur in batch-type plants-mixing, opening and closing of the mixer cover, material discharge, etc.-do not occur. Therefore, production amounts are higher than in batch-type plants.

3-Integrated Asphalt Plant:

These are compact plants with crushing-screening systems. While crushed and separated aggregates are used in classical plants, crushing-screening process is carried out on asphalt plant in compact plants.

Modules in Asphalt Plant and Asphalt Production Stages

Asphalt plants; It consists of feeding silos, conveyor belts, dryer, automatic weigher, mixer and loader modules.

Feeding silos:

Feed silos have an important place in the production process of an asphalt plant. It comprises silos used for storing the various raw materials, which include aggregates, filler materials, and sometimes RAP. Aggregates may be held in separate sections of the silos depending on size and type so that a proper mix is achieved in producing the asphalt mix. These controlled feed systems are installed in the feed silos to provide a constant and uniform feed to the mixing unit. The feed silos must be maintained and monitored well to avoid segregation of material and proper flow of materials to produce good-quality asphalt mixtures. The design and capacity of the feed silos is one of those vital features in any asphalt plant in terms of overall efficiency and output; hence, it's normally a very important part in asphalt production.

Conveyor Belts:

The conveyor belts are among the basic components for manufacturing asphalt and play major roles in the movement of materials within the plant. These belts move the aggregate, filler materials, RAP, and other components within the plant from one area to another. Conveyor belts are load handling heavy and are prepared with mechanisms for the regulation of the speed at which materials can flow. They provide major contributions, ensure continuity, and efficiency while making the material available to the mixing unit at the right time and in correct proportion. The good maintenance of the conveyor belt is quite essential to avoid downtimes, thereby allowing the asphalt plant to run without any disturbance. In an asphalt plant, a variety of conveyor belts are used for particular purposes. For example, the incline belt is utilized in the process of conveying materials to higher components and, on the other hand, the troughed belt that is involved in the transportation of bulk materials. All in all, conveyor belts play a very vital role in the optimization of the production process, hence increasing the overall production of the asphalt plant as a whole.

Dryer:

In an asphalt plant, the dryer drum is that part, which serves to dry and heat the aggregates used in the asphalt mixture. Aggregates such as gravels, sand, or stone are fed into the dryer drum, wherein these are heated to the required temperature. This heat not only displaces the moisture from the aggregates but also preheats them, hence allowing better adhesion with the asphalt binder during mixing. Rotation style is the usual design of the dryer drum so that aggregates could be uniformly heated and dried to ensure uniformity and consistency of the asphalt mix. The efficiency of the dryer drum can make a big difference in the overall quality of the asphalt mix, hence being an essential ingredient in the whole production process. The dryer drum's temperature and speed should be calibrated and controlled accordingly to achieve the desired drying and heating of the aggregate for the optimum production of asphalt mix.

Sieve and hot aggregate bunker:

The hot aggregate coming from the dryer is separated according to their size in the sieves, and the hot aggregate comes to the regabunker. The sieve material is sent back to the crusher. The materials coming to the hot aggregate bunkers are taken to the mixer in the desired amount with the automatic weighing system according to the production recipe.

Mixer:

Mixers form the heart of an asphalt plant where heated aggregates are combined with asphalt binder to produce the final asphalt mixture. The mixer unit usually consists of a twin-shaft pugmill or a drum mixer where the aggregates and asphalt binder are mixed thoroughly to result in a homogenous and well-coated asphalt mix. The mixed material is tumbled in the mixer so that a uniform coating of asphalt binder on the aggregate is achieved. Again, mixing must be accurately controlled so that the desired temperature and time are acquired. This ensures proper blending of materials. At an asphalt plant, proper calibration and maintenance of the mixer have much importance for maintaining consistent mix quality and production efficiency. In that case, the design and efficiency of the mixer will also affect most the performance and quality of asphalt mix to be produced.

Dust Control System:

A dust control system is one of the important devices installed to reduce and keep under control dust particles that are usually emitted during the production process in an asphalt plant. These will include mechanisms and equipment put in place for arresting and containing dust from activities such as aggregate handling, drying, conveying, and mixing. The central aim of the dust control system is the improvement of air quality and adherence to environmental stipulations, along with the provision of a much safer working environment for plant workers. Common components of a dust control system include dust collectors, filters, scrubbers, and ventilation systems. The dust collectors, such as baghouses or cyclones, trap the airborne particles while filters catch the more minute forms of particulate matter. Scrubbers help take away the dust in the exhaust gases, and ventilation systems guarantee adequate airflow, ensuring that dust remains confined within the plant premises. Proper maintenance and monitoring of the dust control system are the reasons an asphalt plant attains environmental sustainability.

Bitumen system:

This includes bitumen storage tanks and a heating system. Bituminous materials coming to the plant from the refinery by heat-insulated vehicles are stored in bitumen tanks. There is a heating system in the tanks to prevent the freezing of the bituminous material. Generally, liquid or gas fueled hot oil boilers are used.