Asphalt batching plant makes hot mix asphalt in batches. It is a mix of several mechanical and electrical components that help make HMA. This equipment can be mobile or stationary. Other types of plant that are available in the market today are drum mix plant and counter flow plants but in general the major categories are batch plant and continuous plants.
Asphalt batch mix plant process involves drying of aggregates and separating each aggregate in different compartments and then mixing them in a twin shaft mixer with bitumen and filler material.
In the drum mix plant, the aggregates are heated and mixed with the bitumen and filler material in a continuous process. Both the process however help in making hot mix asphalt – the difference lies in the process.
Advantages of batching plant:
Most accurate equipment to make hot mix asphalt
It is possible to easily incorporate recycled asphalt in the mix.
It is possible to control the production and quality of the end product.
Components that make a batch are weighed individually before the mixing process.
This plant helps to work with many clients as recipes can be changed easily without compromising on the quality.
Related: Asphalt batch plant vs drum plant
Batch plant components:
In a batch plant, the aggregates are heated, weighed and then mixed with the bitumen and filler material. In certain cases, when there is a need to use recycled material, RAP is weighed separately and then mixed with the weighed aggregates in the mixing unit.
Basic components are as:
Primary screen and charging conveyor
Drying drum with burner
Primary and secondary pollution control devices
Hot oil heater
Filler addition silo / hopper
Batch plant process:
The feeder bins store different sizes of virgin aggregates in separate compartments. The aggregates are then transferred to the drying drum by the help of a conveyor. There is a primary vibrating screen for screening oversized material. Inside the drum, the virgin aggregates will undergo heating and drying process. There is a burner which helps in drying and heating the aggregates. Material enters on the opposite side of the burner and travels the entire drum length to come out from the burners end to be transferred to the vibrating screen on top of the tower unit. Since the entry of aggregates and burner flame is opposite to each other, this process is called as counter-flow process.
Atlas is one of the reputed asphalt batching plant manufacturers from India who focuses more on quality rather than quantity. The tower unit of the machine consists of multiple deck vibrating screen on the top followed by hot bins and below the hot bins is the mixing unit. As the material enters the vibrating screen, they are screened and separated in different compartments as per their size. These storage compartments are known as hot bins.
A required recipe is set in the control panel and weighing of aggregates is done at the hot bins so that the required amount of aggregates is added. Each bin has individual scales which ensure that the correct proportion of each aggregate is weighed and mixed. This ensures that the batching plant is most accurate and delivers the exact material.
At the same time, bitumen and filler material is weighed and added in the mixer. Mixing time is controlled by the control system. After the homogenous mixing, the hot mix asphalt is transferred to storage silos or directly unloaded into waiting trucks.
There are storage tanks for bitumen and also storage facility for filler material. Dry dust collector will help trap heavy dust particles and the finer dust will be trapped by the bag filters. Bag houses are known to be the best pollution control devices for asphalt plant.
The amount of material that the mixer makes in a specific time till it opens its gate for unloading is called as a batch. The total capacity of batches in an hour will determine the production capacity of the equipment.