Neglected but potentially significant emissions of unintentional persistent organic pollutants from primary copper smelting industry.

Abstract

Copper smelting is an important source of unintentional persistent organic pollutants (POPs). Yet emission assessment and inventories remain limited by two key field-evidence gaps: (i) scarce measurement-based emission factors (EFs) for primary copper smelting and (ii) a lack of quantitative constraints on fugitive-derived POP releases. In this study, we conduct field measurements at three primary copper smelting plants and compare POP burdens across end-of-pipe stack gas and a secondary-capture stream capturing fugitive-derived gas. For primary copper smelting using an Ausmelt furnace with electrostatic precipitation as the end-of-pipe control, EFs of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls, and polybrominated dibenzo-p-dioxins and dibenzofurans were estimated at 0.03-0.14, 0.004-0.023, and 0.055-0.062 μg TEQ t⁻¹, respectively. In contrast, reported PCDD/F EFs could be as high as 0.65 μg TEQ t⁻¹ for oxygen-enriched side-blown furnace smelting equipped with baghouse filtration. These results indicate that emissions from primary copper smelting warrant attention in regions with concentrated production activity. The secondary-capture stream exhibited comparable POP concentrations to those in end-of-pipe emissions. Fugitive-related pathways could contribute emissions on the same order as end-of-pipe releases. Fugitive releases should be explicitly considered to reduce systematic underestimation in inventories and associated risk assessments.