Research On Emission And Control Of Sulfur Dioxide And Mercury During Heat Treatment Of Coal And Coal Gangue

Sulfur dioxide and mercury released during the combustion of coal and coal gangue can seriously pollute the atmosphere.The dynamic release of sulfur dioxide and mercury during the combustion of coal and coal gangue will helpful to develop the technologies of reducing the emission of pollutants.In this study,the dynamic release behavior of SO₂ and Hg⁰ during the combustion of coal and coal gangue from the same origin were studied by a laboratory simulation fixed bed.The adsorption of sulfur dioxide and mercury were conducted on a laboratory dynamic adsorption unit with homemade or commercial activated carbon.The raw materials of activated carbon as well as the preparation conditions of activated carbon on the adsorption capacity of sulfur and mercury were studied.The effect of regeneration conditions on adsorption performance of activated carbon was also studied.The main conclusions are as follows:1.During the pyrolysis of coal and coal gangue under nitrogen,the dynamic release of SO₂ shows three peaks,which are respectively located at 300-500 ^oC,500-700 ^oC and 700-1000 ^oC;the dynamic release of Hg⁰ appears two release peaks located at 200-550 ^oC and 550-700 ^oC,respectively.Under the air,only one peak at 300-700 ^oC from the dynamic release of SO₂ for coal and coal gangue can be observed.The dynamic release of Hg⁰ is characterized by a main peak at 150-600 ^oC and a shoulder peak at 200-300 ^oC.The amount of SO₂released under the air is more than that under the N₂ and the amount of Hg⁰ released under the air is less than that under the N₂.The dynamic release of SO₂ and mercury indicates that mercury and sulfur in coal or coal gangue have a positive correlation.2.The overall performance of homemade coal-based activated carbon is better than that of wood-based activated carbon and two commercial activated carbon.The sulfur capacity of activated carbon in this study is as follows:wood-based activated carbon>1#commercial activated carbon?1#coal-based activated carbon>3#coal-based activated carbon>2#coal-based activated carbon>2#commercial activated carbon.1#coal-based activated carbon has a high compressive strength and wear resistance,and the adsorption efficiency of sulfur dioxide is up to 99%,which has a high adsorption effect on sulfur dioxide,after10 cycles of regeneration.3.The mercury removal performance of 1#coal-based activated carbon is better than that of other activated carbon.The mercury capacity of the activated carbon is as follows:1#coal-based activated carbon?1#commercial activated carbon>3#coal-based activated carbon>wood-based activated carbon.1#coal-based activated carbon presents the highest adsorption efficiency of mercury of98%and it still has a high adsorption effect on mercury after 3 cycles of regeneration.