Dual-Pronged Approach: Efficient Recovery of Mercury from Coal-Fired Flue Gas via Swirl-Diffusion Mercury Enrichment Coupled with High Purified HgSe Extraction

Modified magnetospheres (MAG) as a regenerable adsorbent offer a promising alternative to conventional activated carbon injection (ACI) for mercury removal from flue gas. However, large-scale application faces challenges in achieving uniform flue gas dispersion and in high-value recovery of desorbed mercury vapor from spent MAG rich in mercury. In this study, a dual strategy combining swirl injection and value-added HgSe recovery was developed. The swirl injection model was validated at a 315 MW coal-fired power plant, reducing mercury in flue gas to 0.035 μg/m3, with swirl pressure identified as a key factor. An in situ selenium-based recovery agent (I–Se/SiO2) selectively stabilized desorbed Hg0, and DFT calculations indicated that it had significantly higher selectivity toward Hg0 than HgCl2 under flue gas conditions. Continuous field operation achieved 100% mercury recovery as pure HgSe (99.97%) with superior optical properties. Economic analysis showed that system investment and operating costs were only 32% and 19% of those for ACI, with a payback period under one year. This work establishes a new paradigm integrating end-of-pipe mercury abatement with resource recovery in coal-fired power plants.