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Assessment of marble waste utilization as an alternative sorbent to limestone for SO2 control

The possibility of marble waste utilization in wet flue gas desulfurization (WFGD) as an alternative to limestone was assessed. Chemical compositions, specific surface areas, grindabilities, dissolution liabilities and SO2 capture capabilities of five different marble wastes were determined and compared with three limestones used in WFGD systems. Chemical compositions of marble wastes were comparable with limestones, including significant CaCO3 and lower fractions of MgCO3. All limestones and marble wastes had low specific surface areas. Marble wastes had lower Bond Work Indices (BWI) than limestones, implying a higher liability to size reduction. Dissolution behavior was sample specific. Some marble waste types showed higher or comparable dissolution rates with limestones while some resulted in a relatively slower dissolution. A higher calcite favored the dissolution rate while an increase in dolomite reduced the liability to dissolution. Assessment of the FTIR spectra obtained by evolved gas analysis (EGA) revealed better or comparable SO2 retention with some marble waste types as compared to limestones. The capability of SO2 control was a function of the extent of calcite in the sorbents. In view of these, a significant opportunity was anticipated for the wastes of some marble types as an alternative sorbent in WFGD.