Carbonatation is a robust and efficient process to clarify cane sugar refining liquors. In this process calcium hydroxide reacts with carbon dioxide forming a calcium carbonate precipitate. Sugar liquor is separated by filtration for further processing, and Carbonatation sludge is discharged. This sludge represents 1.6 ton (dry basis) per 100 ton of raw sugar and, in certain parts of the world, disposal presents an environmental problem. Some solutions have been presented since the beginning of the century. Until now, solutions found include calcination for reuse in sugar industry, utilisation for agriculture purposes (pH soil correction) and application in ceramic and paint industry. In this work Carbonatation sludge is treated for two purposes: boiler gas desulphurisation and reuse in Carbonatation process. Boiler Fluegases from fossil-flue combustion contains a significant amount of sulphur compounds, mainly sulphur dioxide. Environmental regulations are becoming more stringent, and demand strict control of sulphur emissions to atmosphere. On the other hand, part of boiler flue gases must be treated to remove sulphur compounds with flyashes, before being used in sugar solutions Carbonatation. In Sugar Industry, fluegases for Carbonatation are currently scrubbed with a solution of sodium carbonate. The outcoming wastewater, 6 m~3 per 100 ton of raw sugar, has a high content of sulphuric acid and low pH (1.5 - 2.5) therefore being hard to deal with. To overcome the problem of treating this liquid effluent, a lab-scale facility was constructed to remove SOx and NOx compounds by absorption on dried Carbonatation sludge. Analysis of the gas/carbonatation sludge reactions gave for the SOx compounds a first order reaction removal kinetics. This preliminary study gave a sludge consumption of 0.7 tons (dry basis) of Carbonatation sludge per 100 ton of raw sugar.
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