Drying / Mixing
Before rock aggregate is mixed with other ingredients to make HMA, it is thoroughly dried. The drying and mixing process can be accomplished with one piece of equipment or the functions can be separated. Mixing can take place in a continuous process or in a batch process. Astec supplies a complete line of high-performance drying and mixing equipment to fill the varying needs of producers worldwide. Astec also provides pugmill type mixers which premix additives with rock aggregate.
Double Barrel® Drum Dryer/Mixer
Astec brings you the Double Barrel dryer/drum mixer, the mixer of choice over any other. The Double Barrel dryer/ drum mixer combines the latest in hot mix technology with other great Astec features. Get guaranteed productivity and top quality mixes while keeping operating costs per ton of mix low and meeting the most stringent environmental codes. Stationary, relocatable and portable versions all perform to the same high standards.
Double Barrel® X™ Dryer/Mixer
The Double Barrel X dryer separates the drying process from the mixing process, thereby providing a very reliable plant to be used for the purpose of recycling reclaimed asphalt pavement (RAP). The concept allows for RAP to be pre-conditioned through the external part of the DBX dryer, flashing off moisture in the drum, thus eliminating the problems associated with scavenger systems.
Double Barrel® XHR™ Dryer/Mixer
The Double Barrel XHR system achieves a quality high RAP mix. To achieve this quality mix, Double Barrel XHR system utilizes an outer mixing chamber on the drum, an external mixer, and the V-Pac™ Stack Temperature Control System. The V-Pac™ Stack Temperature Control System allows the system to maintain as low an exhaust temperature as possible when running high RAP content. A stainless-steel drum and stainless-steel combustion flights withstand the higher temperatures associated with running high RAP. The Astec warm mix system comes standard on all Double Barrel XHR mixing systems.
Dillman UniDrum® Dryer Mixer
The Dillman unified drum is a high quality counter flow design that is offered in both portable and stationary arrangements. The UniDrum mixer is offered as part of complete new plants and also for retrofit applications, with a range of production capacities from 200 to 600 tons per hour (182 to 544 tonnes per hour) with 5% moisture.
Warm Mix Systems
Astec can retrofit warm mix systems to continuous mix and batch plants from any manufacturer, bringing the benefits of the Astec warm mix system to all asphalt pavement plant configurations.
Astec burners offer the latest in reliable burner technology combined with complete one-source responsibility. With retrofit capabilities, Astec is able to offer everything from a simple burner replacement to a complete installed system. Astec's burner group engineers the burners to the specifications of each customer and manufactures each in a new state-of-the-art manufacturing facility. Prior to shipment, each burner is tested on one of Astec's three tri-fuel (oil, gas & coal) test stands to ensure fast and easy start-up at installation.
To make good mix on a consistent basis, it is essential to add materials in the right order and at the right time. That's where the Astec exclusive sequential mixing process excels. The Double Barrel® dryer/drum mixer's long mixing chamber and stationary outer shell provide the ability for adding ingredients sequentially. Ingredients are added to the hot dry aggregate in an order that allows better temperature equalization and even distribution of all particles throughout the mix which results in better consistency.
V-Pac™ Stack Temperature Control System
ASTEC's patent-pending V-Pac™ Stack Temperature Control System extends the range of mixes that can be produced without requiring that the flights be adjusted. The system's "V-flights," unique drum flights with a deep V-shape, and its use of variable frequency drives (VFDs), which provide control of the drum rotational speed, are keys to the control system managing an asphalt plant's exhaust gas temperature and increasing overall efficiency.
Drum Mix Coaters
Retrofitting an existing stationary plant with an Astec drum mix coaters (DMC) overcomes the problem many conventional mixers have with hydrocarbons and blue smoke. The coater does the mixing, leaving the drum mixer to function only as a dryer. Single-shaft coaters come in four sizes for production rates up to 525 tph. Dual-shaft coaters are available in six sizes for production rates up to 650 tons per hour.
Parallel-Flow Drum Mixers
Astec's parallel-flow drum mixer is recommended where initial cost of the equipment is an overriding consideration. It is quite suitable for applications where air pollution codes are less restrictive and high percentages of RAP will not be used. It is available in portable and stationary versions. Production rates up to 550 tons per hour are possible.
Astec aggregate dryers feature the same quality construction found on the Double Barrel®. Stationary dryers are used mainly with batch plant facilities. Along with a low pressure oil burner, these units come with the blower burner, automatic burner controls, burner platform, fuel oil pump and ignition platform. The drums are driven by various sized saddle chain or friction drives, based on the drum diameter. The dryers may process up to 500 tons per hour.
TS Batch Towers
The batch tower and hot elevator assembly includes a 3-1/2 deck screen, four hot bins, manual sampling system, aggregate weigh hopper, and liquid asphalt weigh bucket. The dual shaft pugmill features tough Ni-hard liners and mixing paddles. TS batch towers are available in 4, 5, 6 and 8 ton sizes.
BGA Batch Towers
Astec offers the BGA batch tower series from Barber-Greene. These batch towers, now built by Astec, are smaller than the TS models and popular on the international market. Five different BGA towers are available with batch ratings from one to five tons in portable or stationary version.
Super Batch Towers
Super Towers can have as many as 14 bins, providing an amazing 800 tons of hot aggregate storage. This can provide enough rock to run all day without having to replenish the bins. An additional benefit of high storage capacity is the reduced need for stockpile space at the site and minimized dust created by stockpile activity. Super Towers also do an exceptional job with Reclaimed Asphalt Pavement (RAP) mixes because there is space to sandwich a RAP bin between hot aggregate bins.
Post Drum Mixers
Post Drum Mixers are powerful pugmill mixers which incorporate dried aggregate and liquid asphalt to make hot mix asphalt. They can be used as stand-alone units or in combination with a dryer. By removing the liquid asphalt and recycle material from the hot air stream of the dryer, the post drum mixer eliminates emission problems associated with a conventional drum mixer. Capacities up to 400 tons per hour are available.
Lime is often mixed with aggregate to achieve a stronger bond between the rocks and the liquid asphalt. Astec lime pugmills premix the lime and the aggregate before the aggregate enters the dryer. This assures producers an even distribution of the fine lime particles throughout the mix. Slurry systems are also offered. The lime pugmills are sized to fit the production capacity of the facility.