Acta Phys. -Chim. Sin. ›› 2002, Vol. 18 ›› Issue (12): 1116-1119.doi: 10.3866/PKU.WHXB20021212

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Phase Equilibrium of 2MgO•2B2O3•MgCl2•14H2O-MgCl2-H2O System at 30 ℃

Liu Zhi-Hong;Hu Man-Cheng;Gao Shi-Yang   

  1. School of Chemistry and Materials Science, Shaanxi Normal University, Xi’an 710062
  • Received:2002-04-26 Revised:2002-07-02 Published:2002-12-15
  • Contact: Gao Shi-Yang

Abstract: The phase equilibrium of 2MgO•2B2O3•MgCl2•14H2O-MgCl2-H2O system at 30 ℃ has been studied. The experimental results showed that the phase transformation product was inderite(2MgO•3B2O3•15H2O) when the mass fraction of MgCl2 is in the range 0 to 2%, pinnate(MgO•B2O3•3H2O) in the range 2% to 13.8%, demonstrating a great reduction in the temperature of formation of MgO•B2O3•3H2O and providing some physico-chemical basis in explaining the formation of pinnoite mineral in the salt lakes. When the mass fraction of MgCl2 was higher than 13.8%, the chloropinnoite dissolved congruently and did not transform. The mechanisms of the dissolution and phase transformation have been proposed.

Key words: Chloropinnoite, Magnesium chloride, Phase equilibrium