7-1-5 廃石膏の炭素還元(7-1 リサイクル,Session 7 環境対策・リサイクル,研究発表)

概要

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To regenerate the spent gypsum to CaO, calcium sulfate dihydrate was reduced by solid carbon at 1000℃ under a nitrogen stream and change in chemical form of calcium compounds was followed. Calcium compounds in the heat treated samples were classified into sulfate, sulfide and oxide. The effects of carbon amount and heating conditions on the change in forms of calcium were investigated. Desulfurization of CaSO_4 to CaO occurred below 1000℃. Conversion to CaO depended on C/Ca ratio significantly. 87% of calcium was converted to CaO at a mole ratio C/Ca of 0.5. Excess amount of carbon (C/Ca>0.5) caused low desulfurization extent because a part of CaSO_4 was converted to CaS. On the other hand, CaSO_4 was remained at low C/Ca ratio. It was elucidated that the optimum mixing ratio of CaSO_4 and carbon existed to convert gypsum to CaO at 1000℃.
2009-07-30