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Western Aggregates
Lightweight Aggregate Plant
Boulder, Colorado
Roberts & Schaefer provided engineering design, procurement,
and construction management services for Western Aggregate's Lightweight
Aggregate Plant, located near Boulder, Colorado. The facility
was designed around, and incorporated, foundations and structures
from an abandoned cement plant.
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Abandoned Cement Site
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New Facility
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The raw
material handling facility is designed to process 200 TPH of prairie
shale, and includes a near-pit truck dump with reclaim feeder
breaker, overland conveying, secondary crushing, screening and
extrusion of shale fines prior to pyroprocessing. The pyro process
includes a relocated cement kiln, where the shale is heated to
2000 degrees Fahrenheit. At this temperature, the shale expands
to approximately twice its original particle size, with a corresponding
reduction in bulk density. The kiln burner can use coal, natural
gas, or propane fuels. The lightweight aggregate is then cooled
via a reciprocating grate cooler.
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Raw Shale Conveyor
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Cement Kiln Refurbishment
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Cooled lightweight aggregate is crushed, screened, and fractionated
in segregated storage silos. Various ASTM products are produced
by proportionally reclaiming and blending the various size
fractions from storage. The kiln off gas system includes
an FGD (flue gas desulfurization) process including a trombone
cooler, dust collection, and lime slurry scrubbing, with
thickener and vacuum filtration systems for removing and
disposing of scrubber sludge. Ancillaries include warehouse
and maintenance shops, an employee change house, a barge-mounted
process water handler, and water for the fire suppression
system.
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Lightweight Aggregate Loadout |
Offgas Handling |
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