Recyclable CuS sorbent with large mercury adsorption capacity in the presence of SO2 from non-ferrous metal smelting flue gas

Gaseous elemental mercury (Hg0) is difficult to dispose using traditional sorbents when co-existed with high concentration of SO2 from non-ferrous smelting gas. CuS was selected for Hg0 removal from non-ferrous metal smelting flue gas due to large Hg0 uptake capacity under SO2 condition. Hg0 removal experiments indicated that CuS has the largest Hg0 adsorption capacity compared to that of ZnS, CdS, MnS and SnS. The Hg0 adsorption rate and capacity of CuS at 50 °C was 0.0716 mg/(g·min) and 50.17 mg/g with 50% breakthrough threshold, respectively. In addition, the effects of reaction factors such as reaction temperatures and gas components (O2, SO2, H2O, SO3) on Hg0 removal performances were investigated. O2, H2O and SO2 showed negligible influences on Hg0 capture. However, SO3 competed with mercury for adsorption sites, resulting in a decrease of mercury adsorption capacity. The XPS analysis and Hg-TPD results indicated that the adsorbed mercury mainly existed as HgS on the material surface. CuS exhibited high mercury adsorption capacity under SO2 atmosphere at low temperature, appeared to be a promising material for Hg0 capture from non-ferrous metal smelting flue gas. They can be used co-benefit with electrostatic demister (ESD), upstream entering the acid plant for SO2 recovery.