Phase equilibria in the system CaO—Al₂O3—B₂O₃—H₂O at 23 ± 1°C

Phase equilibria in the four-component system CaO—Al₂O₃—B₂O₃—H20 at 23 ± 1°C have been investigated. Data obtained experimentally were used to construct a phase diagram showing the stability regions of the sohd phases Ca(OH)₂, Al(OH)₃, the ternary hydrate 3CaO·Al₂O₃·6H₂O, and the two quaternary hydrates, 6CaO·Al₂O₃·2B₂O₃·39H₂O and 4CaO·Al₂O₃·½B₂O₃·12H₂O. Theoretical calculations were also performed using the speciation program PhreeqC, which gave results that were in close agreement with those obtained experimentally. From this study, the solubility products (PK_sp) for 6CaO·Al₂O₃·2B₂O₃·39H₂O and 4CaO·Al₂O₃·½B₂O₃·12H₂O were determined to be 44·23 and 28·51, respectively.