The bag filters, in the view of its use, has been over-dimensioned : stated the dust granulometry, its quantity on the air m3/sec and the filtering surface,
It is more than sufficiently applied to keep under allowed tolerance the noxious emission: in any case there is an absolute filter behind the bags filter in order to prevent any bad effect in case a bag will break.
The air speed, the type of dust on the air, the temperature, the lead oxide dust’s granulometry bring to choice of a dry filtering system, by means of bags made of a special woven together with an absolute filter for a larger guarantee. There is a cyclone behind the filter. This reduce the dimensions of the bags filter because of the reduced quantity of dust on the air. A Lead oxide level control is placed on the cyclone in order to detect any possible clogging.
A centrifugal fan sucks air from outside through the rotating chamber. In this phase the air brings on itself lead oxide powder and remove the heat generated both by the metals attrition on the wall and by the exothermic reaction of the lead oxidation. The cleaning of the bags is done by blowing compressed air in counter-current, accelerated by venturi scrubbers.