Ya Fei Guo

Supercooling and Phase Separation of Inorganic Salt Hydrates as PCMs

Inorganic salt hydrates as a new type of clean and renewable energy storage materials are widely used in a variety of fields due to their high volumetric latent storage density. However, the supercooling and phase separation effects limit their applications. In this paper, the characteristics of inorganic salt hydrates as PCMs were introduced, and the supercooling and phase separation for inorganic salt hydrates as PCMs were summarized in details. Then, some new approaches of nucleating and thickening agents to overcome the supercooling and phase separation were presented. Finally, the prospects and new trends of salt hydrates as PCMs in the future were also demonstrated.

Studies on Magnesium Chloride Hexahydrate as Phase Change Materials

Magnesium chloride hexahydrate (MgCl2•6H2O), which has a melting temperature of 389.7 K and latent heat of 168.6 kJ/kg, is one of the cheapest materials used as the thermal energy storage material. Like most hydrated salts, MgCl2•6H2O also has the problems of supercooling and phase segregation to limit its application. In this paper, some new progresses on magnesium chloride hexahydrate as phase change materials are summarized, and the new trend in the future is pointed out.

Ionic Liquid Extraction Methods for Alkali and Alkaline Earth Metal Ions

Ionic liquids (ILs) have been considered as successful alternative extraction solvents, especially, they have become potential replacements of volatile organic compound in the extraction of metal ions for the properties of negligible vapor pressure, nonflammability, high thermostability, etc. In this paper, ILs as environmental friendly solvents in liquid-liquid extractions of alkali and alkaline earth metal ions were summarized, the part of extraction phase compositions, extraction conditions and back extraction method were discussed, and the potency of applications of ILs in extraction and separation of metal ions were also commented.

Solubility Prediction for the Reciprocal Quaternary System (Li+, Mg2+//Cl-, SO42-–H2O) at 273.15 K Using Pitzer Ion-Interaction Model

Solubilities of the reciprocal quaternary system (Li+, Mg2+//Cl-, SO42-–H2O) at 273.15K were calculated using Pitzer and its extended HW model. The values of the Pitzer single-salt parameters β(0), β(1), β(2) and Cφ for LiCl, MgCl2, Li2SO4, and MgSO4, the mixed ion-interaction parameters θLi,Mg, θCl,SO4, ψLi,Mg,Cl, ψLi,Mg,SO4, ψLi,Cl,SO4 and ψMg,Cl,SO4, and the Debye–Hückel parameter Aφ in the system at 273.15K were derived either temperature-dependent equation or through fitting solubility data of the ternary system by multiple linear regression method. Based on the Jänecke indexes, the phase diagram was plotted. This study affords the necessary parameters for solubility predictions of complicated systems and establishes a theoretical basis for the separation of these valuable minerals from salt lake brine.

Lithium Recovery Techniques from Solid and Liquid Mineral Resources

Lithium and its compounds are important materials in industry. In this paper, lithium recovery methods both from solid ores and brines were summarized, and the key problems existed were also pointed out. More details for lithium recovery from brines by solvent extraction, ion-exchange, precipitation and calcination leaching methods were discussed, and the new trend for lithium recovery in the future was also carried out.

Synthesis and Thermodynamic Properties of Magnesium Borates

It is well known that the magnesium borates are important materials in all fields. In this paper, the process on synthesis and thermodynamic properties of several hydrated magnesium borates including MgO·2B2O3·9H2O (hungchaoite), MgO·3B2O3·7.5H2O (mcallisterite), MgO·3B2O3·7H2O, 2MgO·3B2O3·17H2O, MgO·3B2O3·5H2O (aksaite) were summarized. The key problems existed and the new trends in the future were also carried out.

Electrodeposition of Lithium in Nonaqueous Solutions and Molten Salts

In this paper, the method of electrodeposition of lithium both in nonaqueous solutions and molten salts was summarized, and the key problems existed were also carried out. More details for electrochemical deposition of lithium metal by ionic liquids including AlCl3-based, EMI-based, BF4--based, PF6--based, Tf2N--based, N(CN)2--based were discussed, and more works needed for lithium recovery by electrochemical method in the future was also pointed out.

Phase Equilibria of the Salt-Water System of Lithium and Borate Ions

It is well known that the exploitation of brine resources of salt lakes is based on the relevant phase equilibrium and phase diagrams. In this paper, the progresses on the stable and metastable equilibria, thermodynamic properties and predictive solubilities of the brine system containing lithium and borate ions at present were summarized. The problems existed and the new trends in the future were also carried out.

Boron Recovery from the Liquid Mineral Resources

In this paper, the processes on boron recovery from the liquid mineral resources (salt lake brine, oil- or gas-field water, and concentrate seawater) including the processes of precipitation, solvent extraction, fractional crystallization, ion exchange, and combined method at present were summarized, and the new trend in the future was also pointed out.

Tellurium Recovery from the Unique Tellurium Ores

Generally, along with the rapid economic development in our country, the requirement of mineral resource is gradually increasing. Compared with the traditional metallurgy, the biohydrometallurgy has the merit of light damage of environment, low cost, and a few investments, and then it can treat with very low-grade ores even industrial disposals. Since the discovery of scattered elemental tellurium deposit in China, the development and utilization of this unique independent tellurium ores were studied. In this paper, firstly, the progresses on tellurium recovery process from the unique tellurium ores were summarized, and then, the experimental results on bioleaching in our lab were presented.