Acta Phys. -Chim. Sin. ›› 2001, Vol. 17 ›› Issue (11): 1021-1026.doi: 10.3866/PKU.WHXB20011112

• ARTICLE • Previous Articles     Next Articles

Crystallization Kinetics of Mg-borates from MgO•3B2O3-18%MgSO4-H2O Supersaturated Solution

Ma Yu-Tao;Xia Shu-Ping;Gao Shi-Yang   

  1. Xi′an Branch,Institute of Salt Lakes,Chinese Academy of Sciences,Xi′an 710043;Institute of Applied Chemistry, Shaanxi Normal University,Xi′an 710062;College of Chemical Engineering, Qinghai University,Xining 810016
  • Received:2001-04-06 Revised:2001-08-13 Published:2001-11-15
  • Contact: Gao Shi-Yang

Abstract: The supersaturated solution of MgO•3B2O3-18%MgSO4-H2O was prepared and kept in a thermostat of (20±0.1) ℃.The crystallization processes of Mg-borates from the solution have been studied by the kinetic method .With the aid of simplex optinum method and digital integration as well as runge-kutta digital solution of differential equation system,the experimental data have been fitted and the kinetic parameters have been evaluated by computer.The crystallization kinetic equation has been given.There are two solid phases ,Macallisterite (MgO•3B2O3•7.5H2O) was firstly crystallized out from the solution and then hungchaoite (MgO•2B2O3•9H2O).The solid phases were identified by IR-spectra,X-ray powder diffraction and TG-DSC thermal analysis.

Key words: Borate, Supersaturated solution, Crystallization kinetics,  Macallisterite, Hungchaoite