Mercury Re-Emission in the Smelting Flue Gas Cleaning Process: The Influence of Arsenite

Recently, the Hg0 re-emission from flue scrubbing solutions has become a research focus. The objective of this study was to evaluate the influence of arsenite on Hg0 re-emission by investigating critical important parameters, including the arsenite ion concentration, pH values, solution temperature, fluorine ion concentration, and chlorine ion concentration. The experimental results indicate that arsenite could directly reduce Hg2+ to Hg0 and promote the decomposition of Hg­(SO3)22–. High pH, temperature, and chlorine ion concentration contributed to the inhibition of Hg0 re-emission, but the fluorine ions had little effect. The mechanism research suggests that the formation of unstable HgH2AsO3+ at low arsenite concentration accelerates Hg0 re-emission. For the Hg­(II)–As­(III)–S­(VI) system, the formation of unstable HgSO3H2AsO3– than Hg­(SO3)22– could increase Hg0 re-emission. With an increase in arsenite concentration, the formation of Hg­(H2AsO3)2 (which comes from the reaction between HgSO3H2AsO3– and H2AsO3–) contributes to the suppression of Hg0 re-emission. The results of this study are conducive to providing new insight into Hg0 re-emission and mercury control.