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The underground brines are large reserves of valuable mineral resources. Aiming at the underground brines of western Sichuan Basin, the phase equilibria of quinary system KCl–KBr–K2SO4–K2B4O7–H2O and its quaternary subsystem KBr–K2SO4–K2B4O7–H2O were studied by using the method of isothermal dissolution equilibrium at 373 K. The phase diagrams, water content diagrams and density-composition relationship diagrams of above two systems were plotted by using the experimental data, respectively. The results show that the quaternary system KBr–K2SO4–K2B4O7–H2O belongs to a simple type; it consists of three univariant curves, one invariant point and three crystallization regions (K2B4O7⋅4H2O, K2SO4, and KBr). The equilibrium phase diagram (saturated with K2SO4) in the quinary system KCl–KBr–K2SO4–K2B4O7–H2O is a type of solid solution, and there are two crystallization regions (K2B4O7⋅4H2O, solid solution K(Cl,Br)) (saturated with K2SO4), one univariant curve and no invariant point.

The isothermal dissolution method was used to study the stable phase equilibria in the quinary system Li+,Na+,Mg2+//Cl–,B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O at 273 K. The dry salt diagram, sodium diagram and water diagram in the quinary system were plotted respectively when Sodium chloride (NaCl) is saturated. The experimental results show that a complex salt lithium carnallite (LiCl·MgCl2·7H2O) is formed in the system. The dry base diagram of this system saturated with NaCl consists of four invariant points, nine univariate curves, and six crystalline regions. The crystalline regions are lithium borate trihydrate (Li2B4O7·3H2O), sodium borate decahydrate (Na2B4O7·10H2O), magnesium borate nonahydrate (MgB4O7·9H2O), lithium chloride dihydrate (LiCl·2H2O), magnesium chloride hexahydrate (MgCl2·6H2O), and the double salts lithium carnallite (LiCl·MgCl2·7H2O), among which sodium borate decahydrate (Na2B4O7·10H2O) has the largest crystalline area that shows that Na2B4O7·10H2O is the easiest to precipitate.

The isothermal equilibrium method was used to study the stable phase equilibria of the quinary system Li+, K+, Mg2+//Cl‒, $${{{\text{B}}}_{{\text{4}}}}{\text{O}}_{7}^{{2 - }}$$ –H2O at 273 K. The solubility data of each component in this system were measured through experiments, and the isothermal phase diagram of this system was also drawn. For the identification of the equilibrium solid phases of the invariant points, X-ray diffraction characterization was used. The projection surface of the stable phase diagram of the quinary system Li+, K+, Mg2+//Cl‒, $${{{\text{B}}}_{{\text{4}}}}{\text{O}}_{7}^{{2 - }}$$ ‒H2O at 273 K was drawn under the saturation condition of MgB4O7. The simplified dry-salt diagram has carnallite (KCl·MgCl2·6H2O) and lithium carnallite (LiCl·MgCl2·7H2O), and it contains eleven univariate solubility curves, five invariant points and seven crystallization regions corresponding to K2B4O7·4H2O, Li2B4O7·3H2O, KCl, MgCl2·6H2O, and LiCl·2H2O and double salts carnallite (KCl·MgCl2·6H2O) and lithium carnallite (LiCl·MgCl2·7H2O). In the quinary system, by comparing the area of each crystalline phase zone, lithium chloride is a highly soluble salt, therefore, in the solubility diagram, in comparison with magnesium tetraborate, it corresponds to the smallest crystallization area.

The isothermal dissolution method was used to study the stable phase equilibria in the simple quaternary system Li+//Cl–, S $${\text{O}}_{4}^{{2 - }}$$ , B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O and reciprocal quaternary system Li+, Mg2+//Cl–, B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O at 273 K. The stable phase equilibrium of simple quaternary system Li+//Cl–, S $${\text{O}}_{4}^{{2 - }}$$ , B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O belongs to hydrate type I, and there is no complex salt. The phase diagram is constituted of an invariant point, three univariant solubility curves, and three solid phase crystalline regions. The stable phase equilibrium of reciprocal quaternary system Li+, Mg2+//Cl–, B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O belongs to complex type, and the double salt of lithium carnallite (LiCl·MgCl2·7H2O) is found. There are three invariant points, seven univariant solubility curves, and five solid phase crystalline regions.

In this work, the activity coefficients of sodium nitrate in the ternary system NaNO3–Cu(NO3)2–H2O were experimentally determined at 298.15 K in the range of total ionic strength I = 0.01 – 1.00 mo...

In the process of mineralization and the extraction, the solubilities of metal minerals are affected by chlorides of alkali and alkaline earth metals, such as NaCl, KCl, MgCl2 and CaCl2, the studies on solubilities of chloride minerals in solutions are of significance for the separation and enrichment of elements in hydrometallurgy. To study the solubility relationships of minerals (such as KCl, MgCl2 and ZnCl2) in aqueous solutions, the phase equilibria of the quaternary system KCl−MgCl2−ZnCl2−H2O at 323 K were investigated by means of the isothermal dissolution equilibrium method. These investigations were carried out and the mineral solubilities were measured. The dry salt phase diagram and water content diagram were plotted and there are three double salts formations of MgZnCl4·6H2O, KMgCl3·6H2O (Car) and 2KCl·ZnCl2. The dry salt phase diagram contains four invariant points and nine isothermal solubility curves, which divide the phase diagram into six crystallization regions, and the crystallization regions correspond to the existence of six equilibrium solid phases, namely ZnCl2, 2KCl·ZnCl2, MgZnCl4·6H2O, MgCl2·6H2O (Bis), Car and KCl. The crystallization zone of KCl is the largest, and those of ZnCl2 and MgCl2·6H2O are the smallest. In addition, the equilibrium solid phases at the invariant points of ternary subsystems at 323 K and 373 K were compared and discussed.

In this paper, the liquid-free battery Na-ISE | NaBr (m1), Na2SO4 (m2) |Br-ISE was used to measure the average activity coefficient of the ternary system NaBr–Na2SO4–H2O at 308.15 K by using the ce...

In this work, the solid-liquid phase equilibrium in the ternary system KCl−KBr−H2O at T = 273 K has been investigated by using the isothermal dissolution equilibrium method. Based on determined solubility data of saturated liquid phase and corresponding humid residue composition, the experimental phase diagram has been constructed. The result shows that the type of the system is classified as completely solid solution type due to the existence of solid solution K(Cl, Br). The phase diagram of the ternary system KCl−KBr−H2O at 273 K is divided into an unsaturated liquid phase filed and one solid crystalline phase region corresponding to K(Cl, Br) by an univariant solubility curve on which there is without any invariant point. The function which described the relationship between the composition of solid solution and the solubility of two salts in saturated liquid phase was constructed by multiple regression. The Pitzer equation has been selected to calculate the solubility data in the ternary system KCl−KBr−H2O at T = 273 K. The solubility modelling approach agrees with experimental solubility data.

In this paper, the stable phase equilibrium data of the ternary system CaBr2-SrBr2-H2O at T = 273, 298, and 323 K and 101.3 kPa have been determined by isothermal the dissolution equilibrium method...

This work describes the solid–liquid phase equilibria in the ternary system SrCl2–SrBr2–H2O at T = 273, 298, and 323 K based on the method of isothermal dissolution equilibrium. Since saturated liq...

The stable phase equilibrium of the two ternary systems LiCl–MgCl2–H2O and SrCl2–MgCl2–H2O at 333 K were researched by using the isothermal dissolution equilibrium method. The solubilities of salts...

In this paper, a sodium ion selective electrode (Na-ISE) and a bromide ion selective electrode (Br-ISE) were used to form a liquid-free potential reversible battery: Na-ISE|NaBr (m1) and SrBr2 (m2)...

Mineral solubilities in the ternary system MgCl2 + SrCl2 + H2O and the quaternary system NaCl + MgCl2 + SrCl2 + H2O at 288 K were measured using the isothermal dissolution equilibrium method. Two p...

The solid–liquid equilibria relationship in the two ternary systems sodium chloride–zinc chloride–water and magnesium chloride–zinc chloride–water at 298 K were investigated based on the isothermal...

The solid–liquid equilibria in the ternary system LiBr–SrBr2–H2O at 273.15, 308.15, and 323.15 K were studied by isothermal dissolution equilibrium method in this work. At three different temperatu...

To provide theoretical data for the hydrometallurgical process of lead–zinc ores and the separation process of secondary lead recovery, the quaternary system MgCl2–PbCl2–ZnCl2–H2O at 323 K was inve...

This paper presents the solid–liquid equilibria phase diagrams of two ternary systems KCl–ZnCl2–H2O and MgCl2–ZnCl2–H2O at 278 K using the method of isothermal dissolution equilibrium. Integrated with the determined equilibrated liquid phase and humid residue composition, the phase diagrams of the two systems were generated. At the same time, the invariant points, the univariant solubility curves and the solid crystalline phase regions are displayed and discussed. The results of the experiment show that the two ternary systems are classified as complex owing to the formation of double salt. The phase diagram of the ternary system KCl–ZnCl2–H2O at 278 K is comprised of two invariant points, three univariant solubility curves and three solid crystalline phase regions corresponding to KCl, ZnCl2·2H2O and 2KCl·ZnCl2·2H2O. The phase diagram of the ternary system MgCl2–ZnCl2–H2O at 278 K includes two invariant points, three univariant solubility curves and three solid crystalline phase regions corresponding to MgCl2·6H2O, MgCl2·ZnCl2·6H2O and ZnCl2·2H2O. The densities of ternary mixtures at 278 K were measured. The possibility of Laliberte model to predict densities of investigated ternary saturated solution was checked. The results show that this model is allowed to offer fundamental description for densities of ternary mixtures and calculated results are in good agreement with the experimental values.

The solubility relationships of the ternary systems KCl–PbCl2–H2O and MgCl2−PbCl2–H2O at 323 K were studied by the isothermal dissolution equilibrium method in this article. In the KCl–PbCl2–H2O sy...

The phase equilibria of the ternary system NaCl–SrCl2–H2O at 273 and 308 K and quaternary system LiCl–NaCl–SrCl2–H2O at 308 K were measured by the isothermal dissolution equilibrium method. The pha...

In this work, the studies of thermodynamic mean activity coefficients of KCl in the KCl–SrCl2–H2O ternary system have been made. A cell without liquid junction battery cell, K–ISE|KCl(mA), SrCl2(mB...

In this article, research on the thermodynamic mean activity coefficients for the ternary system (NaCl–SrCl2–H2O) has been carried out. A cell without a liquid junction can be expressed as sodium–I...

The mean activity coefficients of KCl in the ternary system KCl–CuCl2–H2O were experimentally determined at a temperature of 298.15 K by the EMF method (electromotive force measurement) via a batte...

The ternary system LiCl–SrCl2–H2O and the quaternary system KCl–LiCl–SrCl2–H2O at 308 K were investigated using the isothermal dissolution equilibrium method. According to the obtained experimental...

In view of the characteristic of the deep underground brine that is rich in sodium, potassium, magnesium, calcium, strontium, chlorine, and bromide in the Sichuan basin, solid–liquid equilibria in ...

The solid–liquid equilibrium of the quaternary system (KBr + NaBr + MgBr2 + H2O) was accurately investigated at 298 K. The equilibrium phase diagram was obtained and consisted of seven dissolution isotherms, three co-saturated points and five solid crystallization regions under the condition of 298 K. The five solid crystallization regions contain four single salts NaBr·2H2O, NaBr, KBr, MgBr2·6H2O and one double salt KBr·MgBr2·6H2O, respectively. The largest crystallization region corresponds to KBr comprising more than half of the region of the equilibrium phase diagram. Using Pitzer’s model and mathematical calculation tools, the solubilities of the bromide minerals in this system were calculated; the calculation results are basically consistent with the experimental results. The research in this paper is of great significance in guiding the development of bromine resources of underground brines in the Western Sichuan Basin and providing fundamental thermodynamic data of bromine-containing systems.

The solubility data for ternary systems Na2SO4–Na2B4O7–H2O and Li2B4O7–Na2B4O7–H2O at 273 K were obtained experimentally by the isothermal solution equilibrium method, and the solid phases were analyzed by X-ray diffraction. On the base of the experimental results, the stable phase equilibrium diagrams for these two systems were constructed at 273 K. The stable phase equilibrium diagrams indicate that both phase diagrams show an invariant point, two univariant solubility curves and two solid phase crystalline regions. The two solid phases corresponding to the invariant point of ternary system Na2SO4–Na2B4O7–H2O are Na2B4O7 · 10H2O and Na2SO4 · 10H2O, and the two crystallization regions of the ternary system Li2B4O7–Na2B4O7–H2O are Na2B4O7 · 10H2O and Li2B4O7 · 3H2O, respectively. Thus, the two ternary systems belong to simple co-saturated type without complex salt or solid solution.