The present invention relates to dewatering of gypsum in flue gas desulfurization process based on a limestone forced oxidation technology. The dewatering is enabled and/or greatly enhanced by addition of carboxylic acids, preferably citric acid to the scrubbing slurry. It has been found that carboxylic acids serve as a gypsum crystal habit modifier during gypsum crystallization under forced oxidation. I has been found that under normal operating conditions, i.e. when no acid is added, gypsum crystals assume acicular (needle shape) habit and are difficult to dewater since they tend to retain mother liquor in the filter cake. In the presence of carboxylic acids, preferably citric acid, in scrubbing slurry gypsum crystals assume columnar (bulky) habit and can be readily dewatered in the centrifuge up to 90% solids & period. Also claimed is a device for dewatering gypsum and a cement plant comprising the device.
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