Dehydration Reaction of Phosphogypsum in a Fluidized Bed Reactor

[摘要] A domestic phosphogypsum was calcined in a batch type fluidized bed reactor at various reaction temperatures ranging 90¡­180¡É without and with an alkaline additive amounting up to 5% of gypsum, and physical properties of the resultant products were compared following their characterization by X-ray diffraction pattern and DTA. It has been found that dehydration reactions were uniformly carried out in the fluidized bed reactor and only hemihydrate was obtained at 90¡É whereas at higher temperatures dehydration reaction progressed further. When gypsum was charged to the reactor preheated at over 140¡É, a considerable degree of dehydration occurred before the reactant reached the initially set reactor temperature and in particular, at over 160¡É most of dehydration reaction was performed prior to the present reactor temperature. However, it has been found that gypsum mostly transforms into hemihydrate around the reactant temperature of 140¡É while transformation into anhydrite mostly occurs around 160¡É. When calcium hydroxide was added to gypsum in the reactor, the optimum physical properties of the calcined product were obtained at the weight ratio of Ca(OH2)/P2O5 = 3.2.

[学科分类] 化学（综合）