Abstract:The process for dehydration of bischofite (MgCl2?6H2O) to prepare anhydrous magnesium chloride (MgCl2) with the thermal decomposition of a hydrated double salt is investigated by simulating fixed bed equipment for dehydration with the distilling flask system. The effects of the ratios of aniline hydrochloride (C6H5NH2?HCl) to bischofite, temperature and time of dehydration and thermal decomposition, the concentration of H2O in protection-gas against dehydration on the content of MgO and H2O in the products are described. The technical parameters are optimized. The results show that the optimal temperature and time are 300℃ and 25~30min for the complete removal of H2O, and 320~350℃ and 10~20min for the complete removal of C6H5NH2?HCl, respectively. The optimal ratio of C6H5NH2?HCl to MgCl2?6H2O is 1.1∶1.0. Under the optimal condition, the prepared product, anhydrous magnesium chloride, is desired, containing MgCl2 98%~98.6%, MgO 0.03%~0.38%, C6H5NH2?HCl 0.10%~0.12% and H2O 0.60%~0.81%.