Page 69 - Hub-4 Magazine Issue 58

Asphalt Plant
loadout. The next working day, mix can be sold straightaway from full silos, without awaiting plant startup. Nobody needs to wait for mix and any delays to production plant startup can be mitigated. Uninterrupted production runs allow producers to maximise equipment efficiency and reduce material waste.
Incorporating multiple silos into production plant layouts ensures producers are ready to meet customer needs for a number of different mixes. Whilst reducing operating costs and improving plant operating efficiency.
In addition, the potential to store mix for four days* without loss of mix quality, is guaranteed by Astec in writing. This allows producers to further optimize and rationalize production facilities by utilizing the concept of satellite storage; providing customers with a readily available supply of high-quality mixed material, in areas unsuitable for location of production facilities either due to environmental concerns or economic constraints.
Much more than simple silos:
The Astec long-term storage silos are not just insulated containers but a storage system in which all the elements, starting from the loading hopper, passing through the elevator conveyor and the transverse conveyor up to the silo batcher to the silo and lower cone, are designed to optimize the process.
The main elements that make it a unique technology are:
Insulation:
300mm of insulation at silo tops, 100mm around the cone, and 150mm along the cylinder keep the mix hot. Batchers are insulated as well, because uninsulated batchers are a major source of heat loss. Two layers of stiff sheet insulation are staggered to eliminate heat-leaking seams along the silo- cylinder. Astec uses thick, full R-value, non-compressed insulation.
Top seal:
In storage mode, the cylinder-operated gate at the top of the batcher is completely sealed. The gate runs in rails which tightly wedge it against a ring of grease. This forms a tight seal and keeps air from entering at the silo top.
Bottom seal:
Astec’s patented discharge gate seals the bottom of the cone when the silo is in storage mode. The heated and insulated discharge gate closes to completely cover the cone opening. Oil is pumped into the gate to seal the bottom silo opening.
The oil reservoir is located by the silo legs, and a motor-driven pump moves the oil from the reservoir into the gate. A sensor monitors the oil level in the gate and controls the pump.
Lower cone:
The lower cone has a specific inclination of 66o and a higher shape, which naturally prevents segregation and build-up of the material. To prevent wear caused by the material, the interior is lined with wear-resistant steel or optionally ceramic liners can be installed.
www.hub-4.com September/October 2019 - Issue 58
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