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

Gaseous elemental mercury (Hg-0) is difficult to dispose using traditional sorbents when co-existed with high concentration of SO2 from non-ferrous smelting gas. CuS was selected for Hg-0 removal from non-ferrous metal smelting flue gas due to large Hg-0 uptake capacity under SO2 condition. Hg-0 removal experiments indicated that CuS has the largest Hg-0 adsorption capacity compared to that of ZnS, CdS, MnS and SnS. The Hg-0 adsorption rate and capacity of CuS at 50 degrees 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 (O-2, SO2, H2O, SO3) on Hg-0 removal performances were investigated. O-2, H2O and SO2 showed negligible influences on Hg-0 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 Hg-0 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.