Study on preparation of calcium sulfate whiskers from phosphogypsum and solvent recycling
The preparation of calcium sulfate whiskers from phosphogypsum is one of the ways to achieve high-value utilization of phosphogypsum.Using phosphogypsum as raw material and hydrochloric acid solution as solvent to prepare calcium sulfate whiskers,the effects of reaction temperature and hydrochloric acid concentration on the recovery rate of calcium sulfate,as well as the feasibility of solvent recycling are investigated.The obtained calcium sulfate whiskers are characterized by X-ray diffraction(XRD),scanning electron microscope(SEM).The results show that the optimal process conditions are reaction temperature of 80℃,hydrochloric acid concentration of 2.5 mol/L.The pH of the solution is the main factor affecting the solubility of the solvent,and by adjusting the pH,the solubility of hydrochloric acid solution can be returned to the optimal level,which can be recycled;The prepared calcium sulfate dihydrate whisker product has high purity and the ration of length to diameter is about 25.
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