Description of the Working Process of a Fixed-Site Asphalt Concrete Factory
Description of the working process of a fixed-site asphalt concrete factory
The front-lift loads crushed stone of different fractions delivered in advance, to the hoppers of the inert material warehouse. Loader loads the crushed stone to the inert material warehouse.
Then amount of material, pre-programmed by the operator, is measured, using the dispenser with conveyor belts and fed to the assembly band conveyor. The band conveyor delivers the material to the drying drum.
Once in the drying drum, the material is subjected to heating (drying), with a burner mounted at one end of the drum, which feeds the flame to the drum nuclear. Efficient burners are complex (they operate on fuel oil and diesel fuel).
The drum has good insulation and sealing, that protect it from air penetration. The heating smoothness is achieved by the rotation of the drum together with material. Inner drum walls have special barriers, called bulkheads, catching material.
Material outlet temperature can be controlled in the range between 160 and 200 degrees. The drum design prevents the flame to reach the stone fractures directly, which is very important for the production of qualitative asphalt concrete. The inner wall of the drum, which is closer to the burner, has special metal half-boxes, that prevent materials from the direct contact with the flame. ยางมะตอยสำเร็จรูป
After drying, the material is accumulated in the discharge area of the drum, where the burner is located, and is discharged into the elevator of hot materials, that lifts them up to the top and feeds them into the vibrating screen (separator-crusher).
The vibrating screen (separator-crusher) sorts heated and dried stone materials into 4 fractions, which then reach the hot material bunker with 4 sectors for 4 fractions to be kept for a short time. The bunker sectors are supplied by sensors.
If any of the storage sections are overfilled (e.g. the 5 mm size fraction is not used in the asphalt production), fraction excesses are discharged through the pipe.
From the hot materials bunker compartments, the sorted fractions, in predetermined proportions, are metered into the mixer.
Stone materials as well as powder supplements (fillers) and heated bitumen are fed to the mixer. Powder supplements are stored in a special 30 ton bunker, called powder supplements bunker.
The powder loading to the bunker can be done in two ways:
– Using a pump, that the tank cars delivering powder to the factory are usually equipped with, or
– With the help of the short lifting screw, it is used in case if the powder is prepared in advance. The lifting screw loads to the powder supplements elevator, which lifts them to the bunker. Delivery of powdered supplements into a metering tank is done by the lifting screw