Zinc smelting industry is the main source of atmospheric mercury emission in China. It is of great significance to develop low-cost technology to reduce mercury pollution emission for the green development of zinc smelting. Based on the concept of “using waste to treat waste”, this paper uses high-sulfur slag and secondary zinc oxide produced in the process of zinc smelting to prepare metal zinc sulfide adsorbent by high-temperature sulfurization. The zinc sulfide adsorbents prepared under different conditions were characterized and analyzed by X-ray diffraction (XRD), Raman spectroscopy (Raman), scanning electron microscopy (SEM) and specific surface area analysis (BET), and the effects of different conditions on the mercury removal performance were investigated. The results show that the zinc sulfide adsorbent can be successfully prepared when the roasting temperature and holding time are more than 250 oC and 60 min, respectively. The prepared ZnS-250oC-90min has the best performance for Hg0 adsorption. The average adsorption efficiency of gaseous elemental mercury (Hg0) is above 98% at the flue gas temperature of less than 150 oC, and it exhibits high resistance to O2, SO2 and H2O. The Hg0 adsorption capacity of ZnS-250oC-90min was 3.04 mg/g in the simulated zinc smelting flue gas atmosphere when the Hg0 adsorption efficiency decreased to 50%. The unsaturated short-chain sulfur is the active site for Hg0 adsorption, which can react with Hg0 to form stable HgS, realizing the Hg0 purification from smelting flue gas. The spent adsorbent can be regenerated by using thermal desorption and polysulfide impregnation, and the Hg0 adsorption efficiency remains above 99% after five cycles. Simultaneously, the Hg0 can be recycled in the form of elemental mercury during the regeneration process of ZnS adsorbent. This study not only provides a low-cost method for mercury pollution control and resources recovery from zinc smelting industry, but also promotes the green production of zinc smelting industry.
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