Research On The Metastable Zone Properties Of Boric Acid (Borate) In Bittern System

The solubility and ultra solubility of boric acid under different cooling and heating rates in the systems of M₁Cl-H₃BO₃-H2O, M₂Cl₂-H₃BO₃-H₂O, and M1Cl-M2Cl₂-H₃BO₃-H2O(M₁=Na or K, or Na⁺K, M₂=Mg or Ca, or Mg⁺ Ca) were measured using laser scattering equipment. The metastable zone width and apparent nucleation progression m of boric acid in each system were determined. The main experimental results can be summarized as follows:1. The metastable zone width of boric acid is narrower at high temperature, and is wider at low temperature.2. MgCl₂,CaCl₂ and NaCl lead to a decrease in the solubility of H₃BO₃ in water with MgCl₂ presenting greatest effect, while NaCl presenting the smallest effect.3. The univalent ions(Na+,K+)narrow the metastable zone of H₃BO₃, while bivalent ions(Mg2+,Ca2+) broaden it.4. The influence of MgCl₂ and CaCl₂ on apparent nucleus progression baron of acid's is much more than that of NaCl.5. Although CaCl₂ can broaden the metastable zone of H₃BO₃, The area of the metastable zone of H₃BO₃ in the system of the synthetic CaCl₂-type brines is nearly the same as that in the H₃BO₃-H2O system at the same temperature because of the influence of the co-existed ions.