Characteristic of mercury on the surface of ash originating from electrostatic precipitators of lignite and bituminous coal-fired power plants

Mercury concentrations in ash taken from electrostatic precipitations (ESPs) installed in bituminous coal and lignite power plants have been analyzed by the X-ray fluorescence (XRF) method and leaching test supported by detailed coal and ash compositions' analyses, surface scans and particles size distribution studies. The results showed that mercury was present on the surface of ash particles. Its concentration decreased upon increasing size of ash particles. Leaching tests showed that only small part of mercury was removed with water which suggests the fact that it occurred mostly in the form of insoluble compounds such as Hg, HgO, HgS and Hg2Cl2. There existed ash particles of the diameters from 50 to 60 gm, characterizing by the maximum capability to adsorb mercury and its compounds. The authors suggest that metals like copper and lead formed ash active centers that were preferably occupied by molecules containing atoms of mercury. It was highly possible to expect that content of these elements in ash would have a significant effect on sorption of mercury from combustion gases.Web of Science454594

Effect of HCl on a sorption of mercury from flue gas evolved during incineration of hospital waste using entrained flow adsorbers

Small incinerators of dangerous wastes, including those from hospitals, are a source of emissions of highly variable compositions and concentrations. Mercury is a very dangerous pollutant causing neurotoxicity in human organism. The effect of HCl concentration on adsorption of mercury on activated carbon-based sorbent was studied for the incineration of hospital waste in a 250 kg/h capacity unit. The maximum concentration of adsorbed mercury on activated carbon was determined as a function of concentration of Hg and HCl in combustion products. Based on the expected chemical reactions and the thermodynamics, the adsorption of mercury from flue gases in oxidising atmosphere has been explained. The activated carbon-based sorbent was also capable of adsorbing acid gases like HCl. The efficiency of removal of mercury from combustion products increased up to 85-87% with the concentration of HCl in flue gases. The addition of calcium hydroxide increased the amount of mercury trapped on the sorbent only by about 10%. These tests proved that an entrained flow adsorber is a suitable unit for the removal of mercury from combustion products. The consumption of activated carbon for the mercury removal was from 0.1 to 0.15 mg/Nm3 of flue gas. The advantage of an entrained flow adsorber lies in its easy continuous operation. Therefore, it is a suitable unit for small and medium size incinerators of municipal and hospital waste.Web of Science140807