Deep removal of elemental mercury from non-ferrous metal smelting flue gas: A critical review

The Minamata Convention proposes to reduce mercury (Hg) emissions from non-ferrous metal smelting. According to the Global Mercury Assessment report 2018, Hg emissions from non-ferrous smelting reach 14.9% of global Hg emissions. Existing air pollution control devices (APCDs) can effectively remove oxidized Hg (Hg²⁺) and particle-bound Hg (Hg^P) from non-ferrous smelting flue gases, but are less effective in removing elemental Hg (Hg⁰), so deep removal of Hg⁰ is needed. This paper comprehensively introduces the methods for the deep removal of Hg⁰ from non-ferrous metal smelting flue gas, including absorption (Boliden-Norzink scrubbing, thiourea solution scrubbing, predesulfurization-coabsorption method), adsorption (selenium filter adsorption, carbon filter adsorption, ultrafine nano-sulfur adsorption, metal sulfide adsorption) and other methods (condensation, catalytic oxidation, bioprocessing). The latest research progress of these techniques, including the technical principles, influencing factors and applicable conditions, is reviewed. We also compare the advantages and disadvantages of different methods. Finally, the challenges and research perspectives of these technologies are proposed. This review aims to provide some valuable guidance for the subsequent use and development of Hg removal technologies in the non-ferrous metal smelting industry.