Asphalt plants blend aggregates and liquid bitumen together at high temperatures to produce hot mix asphalt. The three types of plants currently in use in the United States are batch, parallel flow drum mix, and counter flow drum mix plants. The three plant types serve the same purpose and produce the same type of asphalt, but they differ in the material used and operational processes.
A batch plant’s major components are the asphalt cement supply system, cold-feed system, mixing tower, aggregate dryer, and emission-control system. Control panels control the operation of the entire asphalt plant. Batch plants make asphalt aggregate in multiple batches, a process that begins with aggregates being placed in aggregate feeder bins.
Unheated aggregates are fed by size and the gates on bins control the flow of the asphalt aggregates. A conveyor transfers the aggregates to a drying drum that is equipped with flights that promote efficiency in the drying process. Most batch plants have a primary dust collector for settling heavy dust particles and a secondary dust collector, the bag filter.
When the aggregates leave the dryer, they are moved to a vibratory screen that separates them by size. Aggregates are weighed and then transferred to the mixing unit. Aggregates of the desired sizes are mixed with liquid bitumen in a specified proportion.
Bitumen tanks have pumping stations that move it into a weighing hopper that weighs the bitumen before adding it to the mixer. Filler material in a separate container is added to a weighing hopper and then added to the mixer. After mixing for a set period of time, hot mix asphalt then is dropped into a truck or hot storage silo.
Parallel Flow Drum Mix
Parallel flow drum mix plants consist of the cold-feed system, drum mixer, asphalt cement supply system, emission-control equipment, and surge or storage silos. Unlike batch plants, drum plants make asphalt aggregate continuously. In these plants, the dryer dries while mixing the aggregates with liquid bitumen.
The mixer is located at the lower end of the drum so it can be stored in the silos or discharged onto the trucks. Parallel flow asphalt mixers usually use either a dry or wet type of dust collector device for pollution control.
Counter Flow Drum Mix
Counter flow drum mix plants heat and dry asphalt mix in a way similar to conventional batch plant dryers, but they are drum plants that also make hot mix asphalt continuously. The counter-flow drum mixer involves a mixing unit that is folded around an aggregate dryer.
These have the aggregate moving in opposite directions from the flame of the burner. In counter flow drum mix plants, the mixing zone for the bitumen is situated behind the burner flame zone so bitumen doesn’t directly touch the liquid bitumen.
ASPHALT BATCH PLANT COMPONENTS
All types of asphalt plans may have different components, but these are the main ones that ensure the smooth operation of the plant:
- Feed bins for cold aggregate
- Vibrating screen
- Drying drum
- Charging conveyor
- Pre-separator with bag filter
- Hot aggregate bucket elevator
- Multi-deck vibrating screens
- Hot bins
- Bitumen storage tanks and tanks for bitumen transfer
- Mixing equipment
- Weighing hoppers for aggregate, filler, and liquid bitumen material
- Filler storage silos
- Control cabin
- RAP hoppers
- Asphalt storage silos
EVALUATING REPLACEMENTS OF ASPHALT PLANT PARTS
Equipment can be expensive but unfortunately cannot last forever. In asphalt plants, many complex pieces of equipment and machinery are necessary to create the asphalt that we build our roads with.
Regular inspections of your asphalt plant are necessary to prevent large problems. The main locations that need to be observed are the dryers and the baghouse. But looking for wear in less ordinary places can also be important. Analyzing the state of the elevator and how materials are faring can avert issues that lead to downtime.
A plan for maintenance and repairs is an important part of prevention for your asphalt plant. The moving parts especially should be attended to because moving leads to wear that can damage other equipment.
When issues arise in asphalt plants, it can be tempting to repair equipment and parts to keep operating costs down, even when a replacement would be the better option. Especially with economic hardships in the last few years, it’s understandable why businesses have struggled to keep costs low, particularly with expensive asphalt plant parts.
Reinvestment in highway construction has caused a need for reevaluation of priorities concerning asphalt plants. It’s now more important than ever to make sure that your asphalt plant is running properly.
Trunnions with shafts are important to keep your dryer rolling, and issues like broken or worn-out drag chains in conveyors can cause productivity issues. Make sure to get regular maintenance and inspections to determine whether it is in your plant’s best interest to have a repair or replacement.
QUALITY REPLACEMENT PARTS
Your asphalt plant is an investment and runs with high-quality equipment. You don’t save money when you buy cheap replacements; rather, you’re putting your equipment and asphalt plant at risk. Making sure that your parts fit perfectly goes a long way in leading to reduced wear, longer lifespans, and reduced cost over the long term.
ASPHALT PLANT PARTS AND EQUIPMENT AT OUTLOOK ENTERPRISES
Every plant should have available parts stored on-site so it can avoid costly downtime. At Outlook Enterprises, we evaluate and stock the most high-quality asphalt plant parts and equipment such as flights, sprockets, and reducers. We have parts for drum mix and batch type asphalt plants, and if our extensive warehouse doesn’t have the part you need in stock, we can get it quickly for you.
We carry every sprocket and chain used in major manufacturers’ asphalt plants because we know how harmful interruptions in productivity can be. Whether you’re looking for an everyday wear part or a piece of equipment that’s harder to find, contact us to get the parts you need.