Baghouse Dust Return
When baghouse dust is returned to the mix in a batch plant, it must be proportioned by mass and as required in Section 39-3.03 of the Standard Specifications. The typical system used for returning baghouse dust would include an auger that carries dust from the baghouse to the storage
silo, large storage silo, a (high speed) to transport
weigh pot, and a system the dust from the weigh
system must be plant controller.
interlocked to the primary batch The zero and batching tolerances
(interlocks) for this the same as the
type of dust return system are tolerances for “supplemental
fines”, can be found in Standard Specifications. shows a typical system proportioning.
Section 39-3.03 of the The adjacent photograph used for baghouse dust
Hot Aggregate Screening And Storage After the aggregates have been heated and dried, a hot elevator carries them to the screen deck. The screen deck is made up of several different sized vibrating screens. The top screen in the deck is always a scalping screen, which removes oversized
size from top
screen. At the
the deck is
The number of hot bins that to store the different sized
aggregates usually screens in a deck.
The screen deck separates the aggregates into specific sizes. For this process to work properly, the cold feed rates must be in balance with the screen deck capacity. When excessive amounts of aggregate are fed over the screen deck (blinding the screens), or the screen openings become plugged, smaller sized particles that should have passed through there respective screen opening, ride over the screens and drop into a bin designated for a larger sized aggregates. This is commonly referred to as "carry-over". On the other hand, if screens are worn or torn, oversized material will be deposited into bins intended for smaller sized aggregates.
In any case the screens should be inspected and cleaned regularly by the Contractor.