Pilot-Scale Experimental Investigation on Dry Capture of Mercury and SO(3) in Smelting Gas of Acid Making

[Image: see text] In this study, a novel dry capture process utilizing a mixed adsorbent of ZnO and CuS was proposed for the simultaneous removal of Hg(0) and SO(3) in flue gas from zinc smelting, addressing severe mercury pollution and high SO(3) concentrations. The experimental results showed that flue gas cooling caused the SO(3) to transform into sulfuric acid mist, which changed the reaction mechanism from a gas–solid to a liquid–solid reaction and helped to improve the SO(3) removal efficiency. Additionally, properly increasing the absorbent/SO(3) molar ratio significantly improved the SO(3) removal performance. However, excessive absorbent injection could cause aggregation and uneven dispersion of the absorbent particles in the flue gas, therefore impairing the effectiveness of SO(3) capture. Under typical operating conditions (flue gas flow rate of 3500 m(3)/h, flue gas temperature of 180 °C, ZnO/SO(3) molar ratio of 0.74, and residence time of 0.5 s), using a mixed absorbent of ZnO and CuS achieved an SO(3) removal efficiency of up to 32.6%, and a total mercury capture at 43.2%, of which the Hg(0) removal attained a remarkable 76.3%. These results preliminarily confirm the feasibility of the dry capture technology for simultaneous removal of SO(3) and mercury, laying the foundation for further application and promotion.