Acceleration of Hg~0 Adsorption onto Natural Sphalerite by Cu~(2+) Activation during Flotation: Mechanism and Applications in Hg~0 Recovery

摘要

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.