硼酸盐化学(XXXV):MgO·3B_2O_3-18%MgSO_4-H_2O过饱和溶液0℃结晶动力学研究

Chemistry of Borate in Salt Lake Brines(xxxv):Study on Crystallization Kinetics of MgO·3B_2O_3-18%MgSO_4-H_2O Supersaturated Solution at 0℃

首次研究了MgO·3B2 O3 1 8%MgSO4 H2 O过饱和溶液 0℃结晶动力学过程 ,得到三方硼镁石和章氏硼镁石两种固相及其结晶动力学方程。从多聚硼氧配阴离子多粒子共存的角度提出结晶反应机制 ,分析了制约硼酸镁盐析出的因素及不同电解质 (MgCl2 和MgSO4)对硼酸镁盐结晶过程的影响。

In this paper,the crystallization processes of Mg-borates from the MgO·3B 2O 3-18%MgSO 4-H 2O supersaturated solution at 0℃ was studied using kinetics method for the first time.Two solid phases were obtained,namely macallisterite(MgO·3B 2O 3·7.5H 2O)and hungchaoite(MgO·2B 2O 3·9H 2O),which were identified by IR-spectra,X-ray powder diffraction and TG-DTG-DSC thermal analysis,and the crystallization kinetics equations were fitted with the experimental data.According to the viewpoint of coexistence of polyborate anions,the crystallization reaction mechanism has been suggested,and the factors,which affect the crystallization processes of the Mg-borates,also have been discussed.