The dust-collecting system consists of a primary and secondary mechanism. In the primary
system, the relatively bigger size particles are separated from the exhaust gases. This is accomplished
by either expanding the gases, reducing their velocity, and making the heavier particles drop out
in the “knockout box” (expansion chamber process) or by speeding up the gases by directing them
in a spiral flow through a chamber and separating the bigger particles by centrifugal force (cyclone
method). The particles collected in the knockout box or the cyclone chamber are directed to a
mineral filler silo, from where they could be reused for producing HMA.