Solubilities, Densities, Refractive Indices, and pH Values of the Quaternary System (NaCl + NaBO2 + Na2SO4 + H2O) at 308.15 K

Solubilities, densities, refractive indices, and pH values for the quaternary system (NaCl + NaBO2 + Na2SO4 + H2O) at 308.15 K have been experimentally determined using equilibrium isothermal dissolution method for the first time. In this system, there are four crystallization zones corresponding to NaCl, Na2SO4, NaBO2⋅4H2O, and double salt NaCl⋅NaBO2⋅2H2O, and the size of the crystallization areas of minerals is in the order Na2SO4 > NaCl⋅NaBO2⋅2H2O > NaBO2⋅4H2O > NaCl. The solution density, refractive index and pH changed regularly, and calculated values of density and refractive index are in good agreement with experimental data. The obtained experimental results for this quaternary system have significant value for separating and purifying minerals from the salt lake brines of Qaidam Basin.