The foundry sector, particularly when recycled material is being treated, presents the problem of the formation of acidic substances and/or dioxins.
The neutralisation and absorption of these harmful substances occurs by injecting suitable reagents (hydrated ventilated lime and active carbon) into aspiration ducts, taking into consideration accurately calculated contact time requirements under operating conditions at hand. Reagents can be stored inside a storage silos, or stations called "big bag breakers" or "sack breakers".  A ventilator pneumatically conveys substances from the microdoser outlet to a venturi inside the duct, for flow pre-mixing.