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

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.
Competing Interests: The authors declare no competing financial interest.
(© 2023 The Authors. Published by American Chemical Society.)