Aluminum-Enhanced Coal Pyrite Leaching during SO2 Removal with Coal Slurry
2016
Sun, Wenshou | Liu, Jingchun | Wang, Lichao | Yi, Yanqing
During SO₂ removal from flue gas by coal slurry scrubbing, coal pyrite sulfur can be simultaneously reduced. But satisfactory coal pyrite conversion cannot be achieved under normal scrubbing conditions. In the present work, aluminum oxide and aluminum sulfate were tested as additives to enhance the leaching of coal pyrite during SO₂ removal in a bubbling reactor. It was found that adding aluminum oxide or aluminum sulfate into the coal slurry could increase the coal pyrite conversion and SO₂ removal efficiency. The leaching process could be described by the reaction-controlled shrinking core model. Based on the facts that both aluminum and ferric irons can exist in aqueous solution in the form of sulfate and hydroxide complex ions, it was deduced that the attraction between the oppositely charged ions might promote the coal pyrite leaching reactions, suppress the formation of passive Fe solid products, and increase the concentration of soluble complexed Fe(III) which also acted as coal pyrite oxidant.
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