Storage Silo Systems for Asphalt Plants
Storage silo systems are what keep it all together at the end of a continuous hot mix asphalt production process.
With custom-configured, high-performing, heavy-duty silos, drag slat and transfer slat conveyors, and our innovative patented batches, we design stationary and portable self-erecting silo systems that guard against segregation, undue hardening, and temperature loss during storage.
The Components of Asphalt Storage Silo Systems
As the hot mix asphalt leaves the drum mixer in a continuous process asphalt plant, it must either go straight into a truck for transport or into the storage silos Whether just for surge or for longer-term (days, not weeks) storage, each component of the system is essential to preserving the integrity of the mixed asphalt product.
Storage Silo Features
The storage silo, which can be stationary or portable (also called self-erecting) is heated and can be insulated, with well-sealed gates to allow for storage up to a week. Key features include:
- Dual-flow batcher
- Safety gates
- I-beam support legs
- Rigid insulation
We engineer our storage silos, whether stationary or self-erect, to hold up to the harsh environment with high performance and reliability, We insulate the top platform with 10″ of insulation and the sidewalls with 6″ of insulation. The top platform is fabricated from 10″ channel, insulated and capped on top and bottom. It is then directly mounted on the top of the silo can. This provides more structural integrity for mounting the slat.
All the seams in the can and cone are bevel prepped and welded on both sides. This is to ensure 100% weld penetration. The bottom (2) sections of the silo are fabricated from 3/8″ steel. As a result, our silos have added strength and wear life. We line our cones with 3/8″ AR400 “Turtle-back” liners and the can is lined 8′ up the side with 1/4″ AR400.
The cone is equipped with timed, clam-gates. Our cone opening is 39″ in diameter allowing fast unloading. We also have insulated safety gates as a secondary safety measure. These gates are set up to activate if the air pressure drops below the set-point.
Self-Erect Silos
We didn’t cut any corners in the portable self-erect design, so it has all of the quality of our stationary design, with frames built to hold up in harsh climates and tri-axle, air-ride suspension with a 2-axle stinger as standard, all at an affordable cost. This system allows you to get your plant up and running in no time, with a negative weigh system that provides 80 tons of short-term storage at production rates up to 500 tons per hour (TPH). Our silo sets up on a prepared, level surface.
The top of the silo is covered, keeping the heat in and the elements out. The silo has 2” of insulation for added storage life. We use 1” thick Ni-Hard floor liners, heavy-duty, dual strand chain, cone liners, closed top design and we even insulate the silo for added storage time. A caged safety ladder allows access to the top platform, where you would have access to the batcher. Dual, direct-drive reducers on the drive minimize any maintenance on top of the silo. The cone is lined with “turtle-back” liners and it can also be equipped with electric cone heat. Our gate design is a dual, timed, clam gate with a center drop discharge, minimizing segregation.
The silo rests on three equally-spaced load cells located at the base of the cylinder. While leveling a system that uses four load cells can be difficult, three points of contact will always find level. The batched weight is tracked via a load-out system. An optional hydraulic leveling package allows you to fine-tune the leveling. Our telescoping cylinders lift the slat conveyor which is tethered to the silo. The silo is positioned via limit switches, and hydraulic locking pins are actuated to secure the silo into position.
The deployment cycle only takes around 15 minutes.
CWMF Patented Batcher Features
The batcher catches and holds the asphalt briefly at the top of the silo, releasing it in larger batches to be dispersed more evenly throughout the empty or partially-full silo. The dual gate, anti-segregation design is paramount in producing quality mix. The batcher and the silo gates are inter-locked so that the batcher cannot open when the silo gates are open.
Our patented bolt-on batcher component of the silo system allows you to service your gates without removing the batcher, which increases safety and decreases costly downtime. It’s standard at 4 tons with optional extensions for increased capacity and large access doors on two sides. All components are external and gates are removable for easy access and maintenance. With a heavy-duty material splitter and outward opening gates, our batcher minimizes segregation and drops material to the center of the silo, preventing can/cone wear.
U.S. Patent # 10,974,893
Drag Slat and Transfer Slat Conveyor Features
Drag slat and transfer slat conveyors move the mixed asphalt from the drum mixer up to the top of the vertical silo to keep the process moving continuously. Both drag and transfer slats are constructed in a “U” box design with 4140 alloy shafting on the head and tail shafts to ensure optimal strength. We incorporate 1″ thick Ni-Hard, casted liners. These bolt-in liners are “L” shaped and encompass the floor and side liners all in one. Segmented sprockets allow for in-place change-outs. Sprockets are hardened for extended life.
On our drag slats, we use Rexnord chain with ¾” x 8″ A36 weld-in slats. Floating idler shafts allow movement as needed, increasing wear life on the consumable components. Split-hubs on the drag chain withstand the constant abuse thus eliminating hub failure. The hydraulically operated, chain tensioning system is done at the head shaft. This makes it easier versus other mechanical means of adjustment. A threaded rod anchors the adjustment. We also use a positive clamp design on the bearing float plate to eliminate floating movement at the head shaft.
On our transfer conveyors, we use a flop gate design on the diverter gate, bolted onto the main body of the transfer to allow for easy maintenance. We have designed our gates to be completely removed from the body.
