Acceleration of Hg⁰ Adsorption onto Natural Sphalerite by Cu²⁺ Activation during Flotation: Mechanism and Applications in Hg⁰ Recovery

Abstract

The rate of gaseous Hg 0 adsorption onto natural sphalerite increased by approximately 1.9−7.7 times after Cu 2+ activation during flotation of the natural sphalerite to remove impurities. Via a new pathway involving CuS, physically adsorbed Hg 0 was oxidized by CuS to HgS on natural sphalerite after Cu 2+ activation. In a similar intrinsic ZnS pathway, physically adsorbed Hg 0 was oxidized by ZnS to HgS. The rate of the CuS pathway for Hg 0 capture was generally significantly larger than that of the intrinsic ZnS pathway. Thus, Hg 0 adsorption onto natural sphalerite was notably accelerated after Cu 2+ activation. However, the kinetic analysis indicated that the capacity of natural sphalerite for Hg 0 capture did not vary. Because the properties of the activated sphalerite for Zn smelting were barely degraded after Hg 0 capture, the spent activated sphalerite for Hg 0 capture can be reused for Zn smelting. Moreover, most of the gaseous Hg 0 captured by activated sphalerite can be recovered eventually as liquid Hg 0 in the condenser unit of Zn smelters. Thus, Hg 0 recovery by activated sphalerite is a cost-effective and environmentally friendly technology to recover Hg 0 from Zn smelting flue gas, thus replacing the complex and dangerous Boliden−Norzink process.

Mercury Removal from Flue Gas by Noncarbon Sorbents

“…A new interface enriched with S 1– was generated, hence providing adequate adsorption sites for Hg 0 (shown in Figure ). This interface activation method has also been demonstrated for a natural sphalerite …”

Structure-Directing Role of Support on Hg0 Oxidation over V2O5/TiO2 Catalyst Revealed for NOx and Hg0 Simultaneous Control in an SCR Reactor

“…Mercury (Hg) caused various kinds of harmful impacts on human health and biological systems due to its high toxicity and bioaccumulation. − In general, mercury exists in the flue gas in three forms of particle-bound mercury (Hg p ), oxidized mercury (Hg 2+ ), and elemental mercury (Hg 0 ) . Among these mercury-containing compounds, it is extremely difficult to remove Hg 0 by currently available air pollution control devices (APCDs), due to its high volatility and insolubility in water. , To date, several technologies have been successfully developed for Hg 0 control, such as adsorption, − catalytic oxidation, , and photochemical oxidation . Among these, catalytic oxidation of Hg 0 in selective catalytic reduction (SCR) system has proven to be the most economic technology, as which a low-cost option for control of mercury can be achieved by this co-benefit of SCR installation. − Notably, the use of suitable catalysts could effectively promote the Hg 0 oxidation …”

“…4 Among these mercury-containing compounds, it is extremely difficult to remove Hg 0 by currently available air pollution control devices (APCDs), due to its high volatility and insolubility in water. 5,6 To date, several technologies have been successfully developed for Hg 0 control, such as adsorption, 7−9 catalytic oxidation, 10,11 and photochemical oxidation. 12 Among these, catalytic oxidation of Hg 0 in selective catalytic reduction (SCR) system has proven to be the most economic technology, as which a low-cost option for control of mercury can be achieved by this co-benefit of SCR installation.…”

A Molten-Salt Pyrolysis Synthesis Strategy toward Sulfur-Functionalized Carbon for Elemental Mercury Removal from Coal-Combustion Flue Gas

“…Coal combustion is one of the largest industrial sources of mercury emission. The mercury emitted from typical coal-combustion flue gas generally existed in three forms, i.e., elemental mercury (Hg 0 ), oxidized mercury (Hg 2+ ), and particulate bound mercury (Hg p ) [4][5][6][7][8]. The Hg p can be captured by using particulate matter control devices, while the Hg 2+ can be removed by using wet flue-gas scrubbers due to Hg 2+ 's water solubility [9][10][11][12].…”