What is Asphalt Concrete?
The asphalt concrete is the asphalt mixture that the aggregates (sand, stone) in different particle sizes, binders (asphalt or residual oil) and fillers (mineral powder) are mixed according to special proportion.
An Asphalt Profile
Asphalt, as one of road construction materials, has some various names such as blacktop, tar, tarmac, bitumen, macadam and pitch.
The main purpose of asphalt is waterproof and anti-corrosion. Since asphalt is a liquid having of high viscosity and outstanding performance, and it can be synthesized with different mineral materials, it is widely used for waterproof proofs, waterproof ground and anti-corrosion of wood and steel. In addition, there are three types of asphalt: coal coke type, petroleum type and natural type. Because of their different properties, users need to choose according to the actual situation.
Description of an Asphalt Mixing Plant
The asphalt mixing plant, also named asphalt concrete mixing plant, refers to the whole set of equipment which is used for the quantity production of asphalt concrete. It can produce asphalt mixture, modified asphalt mixture and colored asphalt mixture, besides, the asphalt mixing plant is the essential equipment of these construction projects such as motorway, classified highway, municipal service road, airport and harbor.
Types of the Asphalt Mixing Plant
There are different asphalt mixing plants according to the different measuring standards.
- Based on the production capacity divided into: small-size, medium-size and large-size asphalt mixing plant
- The small-size asphalt mixing plant: refers to the plant that the productivity is less than 80t per hour.
- The medium-size asphalt mixing plant: is the plant that the productivity ranges from 100t to 240t per hour.
- The large-size asphalt mixing plant: has very strong production capacity that it can produces 320t per hour.
2. Based on the transfer mode divided into: mobile, stationary and semi-stationary asphalt mixing plant
- The mobile asphalt mixing plant: refers to the plant which is mounted on a trailer frame and can be transferred based on the different construction sites. It is suitable for these projects such as the county-rural roads, low grade highways, road maintenance and mountainous highway.
- The stationary asphalt mixing plant: refers to the plant that the storage hopper and agitation tank need to be fixed on a foundation of cement, which is used for the municipal service roads and high grade highways.
- The semi-stationary asphalt mixing plant: is the plant that the part of equipment is mounted on a trailer and the components need an assembly job at the construction sites. It is commonly used for the first-class highway and below construction.
Flexible & Efficient
Portable & Reliable
3. Based on the mixing method divided into the continuous drum and forced batching asphalt mixing plant
- The continuous drum asphalt mixing plant: is the plant that heating and drying of the cold aggregate and the stirring of mixture are continuously carried out in the same drum.
- The forced batching asphalt mixing plant is the plant that the heating and drying of cold aggregate and the mixing of mixture are forced to be carried out periodically. The process characteristics of asphalt batch mixing plant are: various components are put into the mixer for mixing after being measured in batches. A batch of mixed finished materials is discharged out of the mixer, and the mixing of the next batch of ingredients is then carried out, thus forming a cycle operation process.
The Asphalt Mixing Plant Components
The whole equipment of asphalt mixing plant is composed of the following systems: cold aggregate feeder system, drying system, combustion system, hot aggregate lifting system, screening system, hot aggregate storage system, weighing system, mixing system, dust removal system, powder supply system, dust recovery system, finished material lifting and storage system, pneumatic system, control system, asphalt storage and supply system, forming a complete mixing process system.The some pictures of the relevant components are shown as below:
- Batching Machine(cold aggregate)
The batching machine is equipped with a screen for primary screening to screen out large particles.
- Tilted Belt Feeding Conveyor
The tilted belt feeding conveyor consists of: belt, touch roll, electric engine, reducer, roller, tensioning device and flow filter screen.
- Drier Drum/Drying Drum
The drier drum consists of: drum body, discharge chute, base support, electric engine, reducer and stopping wheel.
The burner: its fuel can be fuel oil, coal or gas.
- Hot Aggregate Lifting System
Hot material lifting machine
- Dust Removal System
Bag-house dust catcher
- Mixing System
External picture of the asphalt mixing tank
Internal picture of the asphalt mixing tank
- Powder Supply System
Powder supply system
- Electric Control System
Control console of the operating room
Host computer and the human-computer interaction touch screen
General control circuit
Equipment Process Principle of the Asphalt Mixing Plant
The process principle of the asphalt mixing plant is mainly including four procedures.
- Procedure I
Shovel the sand and gravel of different particle size into the corresponding cold feed bin with a loader; after volumetric measurement of belt feeder controlled by frequency converter, aggregate is conveyed to the drying drum through aggregate belt conveyor and feeding belt conveyor.
- Procedure II
The drying drum dries and heats the sand and gravel to a certain temperature by counter-current heating. Due to the rotation of the drum, the sand and stone are repeatedly lifted and dropped by the blades to form a material curtain, which enhances the heat exchange effect.
With the help of the dip angle of the drum, the sand and gravel move forward continuously while heating; after coming out of the drum outlet, together with the coarse powder collected by the medium gravity dust collector, it is lifted by the hot aggregate elevator and unloaded into the hot aggregate screening machine.
- Procedure III
The high-temperature flue gas discharged from the drying drum first enters the gravity dust collector through the primary flue for preliminary purification, and the collected powder with a particle size of more than 0.075mm is sent to the inlet of the hot aggregate elevator by the spiral conveyor; then the dusty flue gas enters the bag type dust collector, and the filtered flue gas is directly discharged into the atmosphere via the induced draft fan. The dust collected by the bag type dust collector is sent to the recycling powder supply system for storage by the spiral conveyor.
- Procedure IV
The hot aggregate is divided into several particle sizes through the screening machine, flowing into the corresponding hot material storage bin. According to the designed proportion, the aggregates of different particle sizes are put into the stone measuring bin in batches in the order of small first and then large for cumulative measurement. Meanwhile, the hot asphalt sent by the asphalt supply system and the powder sent by the powder supply system are respectively put into the mixing pot for forced mixing according to the set sequence. The mixed finished materials are unloaded into the finished materials bin for storage, or they can be directly unloaded into the dump truck.
Features of the Forced Batching Mixing Plant and Continuous Mixing Plant
Features of the Forced Batching Mixing Plant:
- The aggregate should be calculated after drying.
- The drying and heating of cold aggregate and mixing of mixture are respectively carried out in two different assembly devices (drying drum and mixer)
- The drying and heating method of cold aggregate is flame counter-current type.
- It has high degree of automation and quality of asphalt mixture, good drying and heating effect, small residual water content of finished material and wide application range.
- High cost of dust removal equipment
Features of the Continuous Mixing Plant:
- The aggregate should be measured before drying and heating.
- The drying, heating and mixing of cold aggregate are carried out in the same assembly device(drying and mixing drum).
- The drying and heating mode of cold aggregate is flame co-current type.
- In the production process, the amount of dust is greatly reduced due to the simplified structure of the continuous mixing plant.
- Due to co-current heating mode, the thermal efficiency is relatively low, the residual water content of the finished mixture is difficult to grasp, and the asphalt may be aged by contacting open fire.
Asphalt Mixing Price
The price of an asphalt mixing plant is to be influenced by these factors such as the asphalt plant types, production capacity, finished material bin types, burner types and so on. The following is the range of price for the asphalt plants available for purchase.
- The price of asphalt batching mixing plant ranges from $200,000 to $5,000,000.
- The price of asphalt drum mixing plant ranges from $100,000 to $3,000,000.
- The price of mobile asphalt mixing plant ranges from $150,000 to $3,500,000.
|Collect Belt Capacity||60t/h||80t/h||100t/h||120t/h||140t/h||200t/h||220t/h|
|Vibrating Screen||4 layer||4 layer||4 layer||4 layer||4 layer||5 layer||5 layer|
|Aggregate Metering hopper||500kg||800kg||1000kg||1300kg||1500kg||2000kg||2500kg|
|Mineral Flour Metering Hopper||120kg||150kg||200kg||200kg||300kg||300kg||320kg|