The gypsum has high water content in FGD system of power plant if the limestone for desulfurization were replaced by white mud.To solve this problem

the scanning electron microscopy and laser particle size analyzer were employed to investigate the compositions and properties of limestone and white mud.Moreover

the effects of particle size of white mud

ferrous ion content and impurity content in white mud on moisture content of the gypsum were studied.The results show that

with the same concentration of desulfurizer

the dissolved oxygen content in white mud slurry was 1/13 of that in the limestone slurry

which is the major reason for high moisture content in the gypsum.The main reasons for the low amount of dissolved oxygen in the white mud slurry are small particle size

high salt content and high Fe~(2+)content.Thus

the gas-liquid mass transfer resistance increased during the desulfurization

the competing for oxygen between Fe~(2+)and SO_3~(2-)led to a serious shortage of oxidation air and poor gypsum dewatering property.Therefore

oxidation fan efficiency and dissolved oxygen in white mud slurry should be increased during the desulfurization using white mud.