The simultaneous centralized control of elemental mercury emission and deep desulfurization from the flue gas using magnetic Mn-Fe spinel as a co-benefit of the wet electrostatic precipitator

Recently, wet electrostatic precipitator (WESP) is proposed to install downstream of the wet flue gas desulfirization (FGD) to control the emission of ultrafine particulates and the gypsum rain. In this work, the simultaneous centralized control of elemental mercury emission and deep desulfurization from the flue gas using magnetic Mn-Fe spinet was developed as a co-benefit of the WESP. Mn-Fe spinet showed an excellent ability for the simultaneous capture of SO2 and Hg-0 at the temperature window of the WESP (i.e. 50-100 degrees C). Its excellent magnetization ensured that it can be easily separated from the mixture with ultrafine particulates in the WESP for the centralized control of Hg pollution. However, Mn-Fe spinel after Hg-0 capture had a serious biological toxicity due to the formation of water soluble HgSO4. Therefore, Mn-Fe spinet after Hg capture was regenerated by the washing of a NaClO solution and the adsorbed Hg-0 on Mn-Fe spinet was then collected as a high concentration of Hg2+ for the safe disposition. Meanwhile, the centralized control of Hg-0 emission by Mn-Fe spinet was cost-effective because Mn-Fe spinet after the regeneration can be used to capture Hg-0 and SO2 for the next cycle with no degradation of the adsorption ability. (C) 2015 Elsevier B.V. All rights reserved.