Solubilities, Densities, and Refractive Indices of the Quaternary System (KCl + MgCl2 + K2B4O7 + MgB4O7 + H2O)

Solubility data for the quaternary system (KCl + MgCl2 + K2B4O7 + MgB4O7 + H2O) is very important for the separation of potassium and boron from the salt lake brines in Qaidam Basin. The solubilities and physicochemical properties including density and refractive index of the quaternary system (KCl + MgCl2 + K2B4O7 + MgB4O7 + H2O) at 318.15 K and 0.1 MPa were investigated experimentally with the method of isothermal dissolution equilibrium. In the phase diagrams of this quaternary system at 318.15 K, there are three invariant points, seven univariant isotherm dissolution curves, and five crystallization regions corresponding to KCl, MgCl2.6H(2)O, K2B4O7.4H(2)O, Mg2B6O11.15H(2)O and double salt KCl.MgCl2.6H(2)O, respectively. The solution density and refractive index of the quaternary system at 318.15 K change regularly with the increasing of Mg2+ concentration.

Automated summary

The solubility data of the quaternary system is crucial for the separation of potassium and boron in salt lake brines. Through experimental investigation, it was found that the solution density and refractive index of the quaternary system change regularly with increasing Mg2+ concentration at 318.15 K. The phase diagrams of the system at this temperature show multiple crystallization regions and invariant points.