New utilizations of natural CuFeS2 as the raw material of Cu smelting for recovering Hg0 from Cu smelting flue gas

Limits on Hg0 emissions from Cu smelting flue gas (Cu-SFG) are stipulated severely by the Minamata Convention. In this work, acid-treated CuFeS2, derived from the simple acid treatment of natural CuFeS2 as the raw material of Cu smelting, was developed as a reusable sorbent to recover Hg0 in the Cu-SFG. Hg0 capture by natural CuFeS2 was closely related to the amounts of adsorption sites and active S22-. After acid treatment, not only the surface of natural CuFeS2 became porous and roughened, but also some impurities in it were removed; hence, more adsorption sites for Hg0 adsorption and more active S22-for oxidizing Hg0 adsorbed were formed on acid-treated CuFeS2, causing its superior performance in capturing Hg0. Moreover, after acid treatment and Hg0 capture, the property of natural CuFeS2 for Cu smelting barely varied, implying that the spent acid-treated CuFeS2 may be reused. Furthermore, most Hg0 in the Cu-SFG can be recovered as liquid Hg using the condensers in Cu smelters. Therefore, Hg0 recovery using acid-treated CuFeS2 was an economically viable and eco-friendly method to control Hg0 emissions from the Cu-SFG, double as a viable way to develop the new utilization of natural CuFeS2 as the raw material of Cu smelting.