褐煤粉煤灰中汞的赋存状态

Occurrence state of mercury in lignite fly ash

用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)及电感耦合等离子体质谱仪(ICP-MS),结合热力学计算、热处理及连续浸出法定性和定量地研究了内蒙古某电厂褐煤粉煤灰中汞的赋存状态。结果表明,粉煤灰中汞可能的赋存状态有Hg Cl2,HgO,Hg S和Hg SO4。随温度升高,粉煤灰中汞含量逐渐降低,温度为500℃时,汞已挥发90%以上。粉煤灰中的汞以Hg Cl2和Hg S为主,分别约占汞总量的35%和42%。

Mercury is one of harmful components in the fly ash.This work took lignite fly ash from a power plant in Inner Mongolia as the research object.The occurrence state of mercury in fly ash was studied by means of X-ray fluorescence spectrometer(XRF),X-ray diffractometer(XRD) and inductively coupled plasma mass spectrometer(ICP-MS),combined with thermodynamic calculation,heat treatment and continuous leaching.The thermodynamic calculation results for possible reactions of mercury with other substances in the flue of coal-fired power plants indicated that the possible forms of mercury in fly ash included HgCl2,Hg O,Hg S and HgSO4.The heat treatment results showed that the mercury content in fly ash gradually decreased with the increase of temperature.When the temperature reached 500 ℃,mercury had been volatilized more than 90%.In order to further determine the form of mercury in fly ash,according to the nature of each mercury compound,the continuous leaching method was used to quantitatively analyze the mercury compounds in fly ash.The results showed that the forms of mercury in fly ash was mainly HgCl2 and Hg S,which accounted for about 35% and 42% of the total mercury,respectively.Studying the specific occurrence state of mercury in fly ash was extremely important for the subsequent removal of mercury from fly ash and improving its comprehensive utilization.