Preparation of calcium sulphate whiskers by recycling method of rare earth gypsum mother liquor and study of their crystal transformation and properties
In the article,calcium sulfate whiskers were prepared by microwave method using the waste slag(rare earth gypsum)generated from the rare earth metallurgical process as the raw material.Then the effect of mother liquor circulation on the preparation of calcium sulfate whiskers and their crystal transformation was explored.The crystal transformation conditions of calcium sulfate whiskers were clarified.Finally,the properties of calcium sulfate were investigated.The structure,morphology and properties of calcium sulfate whiskers were characterized and analyzed by X-ray diffractometer(XRD),scanning electron microscope(SEM),thermogravimetric-differential calorimetric analyzer(TG),Fourier-transform infrared spectrometry(FT-IR),and atomic force-Raman and fluorescence spectrometry(F-4600).The results showed that the morphology and crystal structure of the whiskers were stable with an average length of 92.4pm and an aspect ratio of 13.7 after three cycles of the mother liquor,indicating that the mother liquor recycling scheme was feasible.The recycled products were dried by regulating the drying temperature,and dihydrate,hemihydrate and anhydrous calcium sulfate whiskers were prepared at 80℃,90℃ and 420℃,respectively.All three prepared calcium sulfate whiskers had the performance of absorbing UV light and emitting blue light,among which the hemihydrate calcium sulfate whiskers had the best luminescence performance.The recycling of solid waste and mother liquor improved the resource utilization efficiency in the process of waste residue and waste liquid treatment,and reduced the adverse impact on the environment.By regulating the crystal shape of calcium sulfate whiskers and endowing them with luminescent properties,new directions for exploring the application fields of calcium sulfate whiskers were provided,and at the same time,new ideas for the clean production of rare earth metallurgy were offered.
万方数据
维普
