Case study of polychlorinated naphthalene emissions and factors influencing emission variations in secondary aluminum production

Abstract

h i g h l i g h t s• Variations in PCN emissions from different smelting stages were observed.• Factors influencing PCN emission levels and profiles were identified.• Addition of chloride additives possibly promote PCN formations.• Emission factors for gaseous and various solid discharges were derived.• This study is helpful for developing better control strategies for PCN reduction. Keywords: Secondary aluminum production Smelting stages Polychlorinated naphthalene Solid residues Chloride additives a b s t r a c t Secondary aluminum production has been recognized as an important source of polychlorinated naphthalenes (PCNs). Large variations in PCN emissions as the smelting process proceeds have not been determined. In this study, solid and gaseous discharges, including fly ash, slag, and stack gas samples collected from four secondary smelting plants during different smelting stages were analyzed for PCNs. The average emission factor of 1−8 PCNs to air was calculated to be 17.4 mg t −1 , with a range of 4.3-29.5 mg t −1 . The average emission factors of 1-8 PCNs from fly ash and slag were 55.5 ng t −1 and 0.13 ng t −1 , respectively. The derived emission factors may enable a more accurate estimation of annual emissions and a more comprehensive knowledge of the distribution of PCNs emitted from secondary aluminum production. The emission levels and characteristics of PCNs during different smelting stages were compared. Possible factors, including the organic impurities from aluminum scrap, fuel, and chloride additives, which could contribute to variations in PCN emissions and characteristics were discussed. These results may provide useful information for developing better control strategies for reducing PCN emissions in secondary aluminum production.

Variations and factors that influence the formation of polychlorinated naphthalenes in cement kilns co-processing solid waste

“…The stack gas sampling method has been described in detail previously [20,21]. An isotope dilution high-resolution gas chromatography and high-resolution mass spectrometry method described previously was used to determine the PCN concentrations in the samples [20,22,23]. Each stack gas or solid sample was spiked with a 13 C 10 -labeled PCN internal standard mixture (ECN-5102, containing the 13 C 10 -labeled tetra-to octa-chlorinated naphthalenes CN-27, CN-42, CN-52, CN-67, CN-73, and CN-75; Cambridge Isotope Laboratories, Andover, MA, USA).…”

Formation and emission of brominated dioxins and furans during secondary aluminum smelting processes

“…Secondary aluminum production in China is mostly performed using reverberatory furnaces because such furnaces have simple structures, are easy to operate, and are suitable for large-scale production (Hu et al, 2013b;Jiang et al, 2015). Scrap containing aluminum is the main raw material used in Chinese SAl plants.…”

“…Scrap containing aluminum is the main raw material used in Chinese SAl plants. Fabric bag filters are widely used as air pollution control devices in Chinese SAl plants Hu et al, 2013b;Jiang et al, 2015). Four typical Chinese SAl plants with reverberatory furnaces and bag filter air pollution control devices were studied.…”

“…The formation and emission of PCDD/Fs, PCBs, and PCNs during SAl processes have previously been studied in detail, and SAl has been found to be an important source of these chlorinated compounds (Chen et al, 2004;Lee et al, 2005;Li et al, 2007;Ba et al, 2010;Hu et al, 2014;Jiang et al, 2015). Ba et al (Ba et al, 2009 measured PCDD/F, dioxin-like PCB, and PCN emissions from Chinese secondary aluminum metallurgical plants and estimated that the total amounts of PCDD/Fs, dioxin-like PCBs, and PCNs emitted to the atmosphere in 2007 were 7.3, 0.53, and 0.39 g toxic equivalents (TEQ), respectively.…”

“…Intensive studies of PCDD/F, PCB, and PCN emissions during SAl processes have been performed (Chen et al, 2004;Lee et al, 2005;Li et al, 2007;Ba et al, 2010;Hu et al, 2014;Jiang et al, 2015), but emissions of the toxic brominated analogs of these pollutants, particularly PBDD/Fs, have been investigated in few studies. PBDD/ Fs are the brominated analogs of PCDD/Fs, so PBDD/Fs have similar physicochemical properties, toxicities, and environmental behaviors to PCDD/Fs (Behnisch et al, 2003;Birnbaum et al, 2003;Olsman et al, 2007;Samara et al, 2009).…”