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An isothermal dissolution method was employed to investigate the phase equilibrium at 308 K of the mixed aqueous system containing lithium, magnesium, sulfate, and borate. The solid phases of the invariant points were confirmed with the X-ray diffraction method. The stable phase diagram, the water content diagram, and the diagrams of the physicochemical properties versus the composition of the solution have been constructed. The system contained two invariant points (noted as E1 and E2), five univariant curves, and four crystallization fields corresponding to single salts epsomite (MgSO4·7H2O), hungchaoite (MgB4O7·9H2O), lithium sulfate monohydrate (Li2SO4·H2O), and lithium borate trihydrate (Li2B4O7·3H2O). Invariant points E1 and E2 are of commensurate invariant points. The crystallization fields decrease in the sequence MgB4O7·9H2O, Li2B4O7·3H2O, Li2SO4·H2O, and MgSO4·7H2O, which was contrary with the solubility of the salts. Compared with the temperature at 298 K, the crystallization area of salts MgB4...

The solid–liquid equilibrium of reciprocal quaternary system Cd2+, K+//Cl–, SO42––H2O at 298 K was studied by an isothermal solution saturation method. Experimental results indicate that there are nine univariant curves F2E2, F4E4, E2E1, F3E1, E1E3, F5E3, F1E3, F6E4, and E4E2, four invariant points E1, E2, E3, and E4, and six crystallization fields in the reciprocal quaternary system. There are two double salts existing in the reciprocal quaternary system. The crystallization zones of equilibrium solid phases are K2SO4 (F2E2F4), KCl (F4E2E1F3), CdCl2·H2O (F5E3F1), Cd3KCl7·4H2O (F3E1E3F5), 3CdSO4·8H2O (F1E3E1E2F2), and KCdCl3 (E1E2E4F6F3). The point E1 represents the equilibrium of the three-solid phase KCl + Cd3KCl7·4H2O + 3CdSO4·8H2O. The eutectic point E2 represents the equilibrium of the three-solid phase K2SO4 + KCl + 3CdSO4·8H2O. The eutectic point E3 represents the equilibrium of three-solid phase Cd3KCl7·4H2O + CdCl2·H2O + 3CdSO4·8H2O. The other eutectic point E4 represents the equilibrium of the t...

Metastable equilibrium solubilities and such physico-chemical properties as densities, conductivity, pH, refractive index and viscosity of the solution for the quaternary system Li2B4O7+Na2B4O7+K2B4O7+H2O at 15 °C were determined experimentally. According to the experimental data, the metastable equilibrium phase diagram was plotted. In the metastable phase diagram, there are one invariant point, three univariant curves, and three fields of crystallization: Li2B2O4·16H2O, Na2B4O7·10H2O, and K2B4O7·4H2O. Potassium borate (K2B4O7·4H2O) has the smallest crystallization field and sodium borate (borax) has the biggest one. Also, the relationship diagram between the properties and the ion concentration of solution was constructed. It can be seen from the relationship diagram that the metastable equilibrium solution density values, viscosity values and refractive index values are increased apparently with the rise of lithium borate concentration, reaching the maximum values at invariant point F. Electrical conductivity values and pH values, however, fall down with the rise of ion concentration on the whole.

An experimental study on phase equilibria at 288 K in the quinary system Li+ + Na+ + K+ + SO42- + B4O72- + H2O was performed using the isothermal evaporation method. Equilibrium solubility and density of the solution were measured. The equilibrium phase diagram for the solution saturated with the salt Li2B2O4·16H2O was constructed. The phase diagram of this system consists of 7 invariant points, 14 univariant curves, and 8 crystallization fields corresponding to potassium tetraborate pentahydrate (K2B4O7·5H2O), borax (Na2B4O7·10H2O), potassium sulfate, lithium sulfate monohydrate (Li2SO4·H2O), sodium sulfate, lithium−potassium sulfate double salt (Li2SO4·K2SO4), lithium−sodium sulfate double salt (Li2SO4·Na2SO4), and potassium−sodium sulfate double salt (3K2SO4·Na2SO4). There are three kinds of double salts formed in the system. The crystallization forms of lithium and potassium borate were K2B4O7·5H2O and Li2B2O4·16H2O, respectively, which are different from the usual forms of K2B4O7·4H2O and Li2B4O7·3H2...