Combusting fuel formed from waste. reduction in emission of chromium, nickel and lead

Thermal waste treatment processes dramatically reduce their volume and mass. Unfortunately, they also cause environmental nuisance associated with emissions of harmful substances. The emissions of toxic heavy metals into the air are of particular interest. Low effectiveness of dust extraction equipment for submicron size particles does not provide ecological safety. The paper presents the results of heavy metal (chromium, nickel and lead) emissions from fuel formed from waste combustion. It presents the possibility of reducing that emission by binding heavy metals in the residue scraper. As immobilising metal additives, substances such as: V₂O₅ and Na₂B₄O₇ were used. Obtained reduction of heavy metal emission was of up to tens percent. In a series of studies, where in addition to Na₂B₄O₇ and V₂O₅, CaCO₃ was added, an additional effect of metal retention in the residue scraper was obtained. Chalk binds chlorine released from the fuel combustible material, which in turn prevents the transformation of heavy metals to form chlorides. Binding of hydrogen chloride from the gas atmosphere of the boiler to calcium chloride, eliminates the ability to create heavy metal chlorides. Addition of chalk reduces also its HCl emission and thus minimizes corrosion of the boiler components.