Thermodynamic models for metal-salt-oxide liquid solutions

该研究计划的目标是开发一种强大而系统的方法来模拟混合金属和离子熔体相，以便获得可靠的预测液态热力学性质及其与固相和气相在具有工业和科学价值的多组分体系中的平衡。不同条件下原生金属的生产、物种的扩散。CALPHAD方法已经成为计算冶金和化学无机体系相平衡和热力学性质的强制性工具。它包括发展吉布斯能量函数，根据实验数据和第一性原理计算，对化学体系中的每一个给定的相进行校准。化学平衡和相平衡可以通过使用最小化技术来计算，该技术应用于寻找在能量中给出最小值的相的组合和组成。这种方法现在在世界范围内被应用于多组分化学体系。 不幸的是，对液态金属和熔融氧化物/盐之间的混溶和不混溶的适当模拟还没有很好地建立，特别是关于影响其电导率的已知化学物种。熔融金属-盐平衡表现为完全液体混溶(Fe-FeS、Cs-CsC l)、部分混溶(Cu-Cu2O)、强不混溶(Cu-Cu2S、Li-LiF)或几乎完全不混溶(Mg-MgCl2)。 该项目的科学方法在于系统地测试和实施液体热力学模型，该模型将使用电导率测量得到的离子物种，以单一的吉布斯能量函数覆盖液态金属和离子组成范围之间的完整组成范围。该模型将用于碱金属-碱卤化物、镁-镉-铋氯化物和具有部分离子性质的金属合金，如碱-重金属，最后用于铜冶炼和吹炼的铜-铁-S-O-硅系统。该研究首次实现了对金属在离子熔体中的溶解和非金属在合金中的溶解的正确评价。加拿大将受益于金属生产领域(铜冶炼、特殊金属和合金)以及通过提高电解电流效率而提高的能源效率。

The objective of the proposed research program is to develop a strong and systematic approach for the modeling of mixed metallic and ionic molten phases in order to obtain reliable predictions of the liquid phase thermodynamic properties and its equilibria with solid and gas phases in multicomponent systems of industrial and scientific interests. Primary metals production tions, diffusion of species under different conditions. The CALPHAD Method has very strongly established itself as a mandatory tool in the calculation of phase equilibria and thermodynamic properties of metallurgical and chemical inorganic systems. It consists in developing Gibbs energy functions, calibrated on experimental data and First-Principles calculations, for every given phase in a chemical system. Chemical and phase equilibria can be computed by the use of minimization techniques applied to find the combination and composition of phases that give a minimum in the energy. This approach is now applied worldwide for multicomponent chemical systems. Unfortunately, the proper modeling of the miscibility and immiscibility between liquid metals and molten oxides/salts is not well established, especially relative to the known chemical species that are affecting their electrical conductivity. Molten metal-salt equilibria show cases of full liquid miscibility (Fe-FeS, Cs-CsCl), partial miscibility (Cu-Cu2O), strong immiscibility (Cu-Cu2S, Li-LiF), or virtually complete immiscibility (Mg-MgCl2). The scientific approach in this project consist in systematic tests and implementation of a liquid thermodynamic model which will use ion species derived from the electrical conductivity measurements to cover, with a single Gibbs energy function, the complete composition range between the liquid metal and the ionic composition range. This model will be tested for alkali metal-alkali halide salts, for Mg-Cd-Bi-chlorides and for metal alloys that exhibits a partial ionic character, such as the alkali-heavy metals, and finally for the Cu-Fe-S-O-Si system used for Cu-smelting and converting. For the first time, the proposed research permit to evaluate correctly both the metal dissolution in ionic melts and non-metal dissolution in alloys. Benefits for Canada will be in the field of metal production (Cu smelting, specialty metals and alloys) and in the energy efficiency by increasing current efficiency in electrolysis.