Solid–Liquid Equilibria (SLE) of the Quinary Reciprocal Aqueous System Li⁺, K⁺, Rb⁺//Cl^–, Borate-H₂O at 323.2 K

Abstract

The isothermal dissolution method was applied for the phase equilibria experiment of the reciprocal quinary system Li+, K+, Rb+//Cl–, Borate-H2O at 323.2 K; the related density (ρ) of the system was measured by the specific gravity bottle method experimentally, and the crystalloid forms of the equilibrated solid phase were identified by the X-ray diffraction method. Results show that the system belongs to a complex type with the formation of solid solution [(K, Rb)­Cl]; meanwhile, six single salts, LiCl·H2O, KCl, RbCl, Li2B4O7·3H2O, K2B4O5(OH)4·2H2O, and RbB5O6(OH)4·2H2O, were also formed at 323.2 K; no double salt was found in this system. The space phase diagram consists of five quinary invariant points, fifteen isothermal dissolution curves, and seven crystallization fields. The size of the RbB5O6(OH)4·2H2O crystallization field is the largest among the coexisting salts in the quinary system. Under the condition of RbB5O8 saturation, the crystallization field of Li2B4O7·3H2O occupied the largest crystallization region, and salt RbCl had the smallest region.

Solid–Liquid Equilibria of the Quinary System Li+, K+, Mg2+//Cl–, B4O72––H2O at 323.2 K

“…−H 2 O, 10 Li + , Mg 2+ //Cl − − H 2 O, 11,12 Li + , K + //Cl − −H 2 O, 12 K + , Rb + //Cl − −H 2 O, 13 and K + , Mg 2+ //Cl − −H 2 O; 13 quaternary systems Li + , K + , Rb + // borate−H 2 O, 14 K + , Rb + //Cl − , borate−H 2 O, 15 Li + , Rb + //Cl − , borate−H 2 O, 16 and Li + , Mg 2+ //Cl − , borate−H 2 O; 17 quinary systems Li + , K + , Rb + , Mg 2+ //borate−H 2 O, 18, 19 Li + , K + , Rb + , Mg 2+ //Cl − −H 2 O, 20 Li + , K + , Rb + //Cl − , borate−H 2 O, 21 and Li + , Na + , Mg 2+ //Cl − , B 4 O 7 2− −H 2 O. 22 The results of studies show that lithium carnallite LiCl•MgCl 2 •7H 2 O is easily produced in the chloride coexistence system of lithium and magnesium, carnallite KCl•MgCl 2 •6H 2 O is formed in the coexistence system of potassium and magnesium, rubidium carnallite RbCl•MgCl 2 •6H 2 O is found in the chloride type system containing magnesium and rubidium, and solid solution [(K, Rb)Cl] is formed in the coexistence system of potassium and rubidium.…”

“…According to the composition characteristics of potassium-rich brine in Sichuan Basin (especially Pingluoba brine), it can be simplified as the system Li + , Na + , K + , Rb + , Mg 2+ //Cl – , B 4 O 7 2– –H 2 O. For the system, there have been some studies on the phase equilibria of its subsystems, − for example, ternary systems Li + //BO 2 – , B 4 O 7 2– –H 2 O, Li + , Mg 2+ //Cl – –H 2 O, , Li + , K + //Cl – –H 2 O, K + , Rb + //Cl – –H 2 O, and K + , Mg 2+ //Cl – –H 2 O; quaternary systems Li + , K + , Rb + //borate–H 2 O, K + , Rb + //Cl – , borate–H 2 O, Li + , Rb + //Cl – , borate–H 2 O, and Li + , Mg 2+ //Cl – , borate–H 2 O; quinary systems Li + , K + , Rb + , Mg 2+ //borate–H 2 O, , Li + , K + , Rb + , Mg 2+ //Cl – –H 2 O, Li + , K + , Rb + //Cl – , borate–H 2 O, and Li + , Na + , Mg 2+ //Cl – , B 4 O 7 2– –H 2 O . The results of studies show that lithium carnallite LiCl·MgCl 2 ·7H 2 O is easily produced in the chloride coexistence system of lithium and magnesium, carnallite KCl·MgCl 2 ·6H 2 O is formed in the coexistence system of potassium and magnesium, rubidium carnallite RbCl·MgCl 2 ·6H 2 O is found in the chloride type system containing magnesium and rubidium, and solid solution [(K, Rb)­Cl] is formed in the coexistence system of potassium and rubidium.…”