Production of phosphoric acid by using wet process technology in China is challenging due to high impurities (P2O5 present is less than 25 wt %). Extraction of phosphoric acid from such low concentration mixtures needs to be improved. Moreover, the separation of chloride and phosphate ions is also important for the subsequent production of phosphate fertilizers. In this study, an organic solvent composed of trialkyl amine (N235), isoamyl alcohol, and sulfonated kerosene was developed to extract phosphoric acid. Pseudoternary phase equilibria, two phase densities, and the viscosities were determined at 298.15 K and atmospheric pressure. Results show that unlike other common organic solvents, the proposed solvent exhibits relatively higher extraction capacity even at low phosphoric acid concentration (P2O5 less than 25 wt %). The separation factor of chloride and phosphate ions reaches up to 39.45 and is several orders of magnitude lager than other common organic solvents including alcohols, cyclohexane, and tri-n-butyl phosphate (TBP). In addition, the solubility of organic solvent in the aqueous phase is close to zero, while the water content in the organic phase keeps nearly constant at a low concentration of around 5 wt %. All of these indicated that the developed solvent mixture is efficient for the extraction of phosphoric acid.

In the electrolysis lithium industry, liquid lithium metal and chloride gas need to be separated quickly because of the recombination of lithium and chloride. A new stirring system can help to separate liquid metal and chloride in lithium electrolysis cells. The stirring system was tried in a cold model to get the right parameters. Computational Fluid Dynamics (CFD) and Particle Image Velocimetry (PIV) were both employed to design and optimize the device parameters which included impeller type, diameter, position and rotational speed. PIV tests and CFD model validation were conducted in a cylindrical stirred tank. Different turbulence models were applied and the standard k–ε model was considered as the most suitable one. The results show that: the propeller agitator properties of a low blade number and low installation position were advantageous to the lithium collection. The impeller diameter and rotational speed have positive effects on the expected flow field. The simulation results were applied in cold model experiments, which showed that the simulations are correct and can be used in real separator design.

•Li+ weakens interaction between counterions and affects closed packs between ions.•Self-diffusion coefficients present positive dependences on Li+ contents.•Shear viscosities exhibit complicated variations with different concentrations.•Ionic conductivities show positive dependence on Li+ contents, but negative on K+.The structures and dynamic properties of molten alkali binary chlorides LiCl–NaCl, LiCl–KCl and KCl–NaCl at 1100 K have been calculated across the full composition range in this paper in detail by molecular dynamics simulations. The effects of LiCl on the local structures and transport properties as the self-diffusion coefficients, viscosities and ionic conductivities of molten NaCl and KCl as well as the mixing effects between NaCl and KCl have been calculated and analyzed. The results reveal that the Tosi-Fumi potential predicts negative composition dependence for density and positive composition dependences for ionic diffusivity and ionic conductivity as the contents of LiCl are increased for molten LiCl–NaCl and LiCl–KCl. As the KCl contents are increased, the ionic diffusivity of molten KCl–NaCl shows weak composition dependence. However, the density and ionic conductivity exhibit negative composition dependences. The transport performances of these mixed melts are dominated by the local structures and interatomic forces. The shear viscosities of the mixtures decrease firstly and then increase under the influences of these two factors. For molten KCl or NaCl, with the addition of a smaller cation (Li+), the interactions between counter ions and closed packs between anions are weakened, while closed packs between cations are promoted. What's more, the smaller the added ion is, the more pronounced the effects are. However, the addition of a larger cation presents the opposite effects.

Electric field is the energy foundation of the electrolysis process and the source of the multiphysical fields in a magnesium electrolysis cell. In this study, a three-dimensional numerical model was developed and used to calculate electric field at the steady state through the finite element analysis. Based on the simulation of the electric field, the operational and structural parameters, such as the current intensity, anode thickness, cathode thickness, and anode-cathode distance (ACD), were investigated to obtain the minimum cell voltage. The optimization is to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The results indicate that the effect of the current intensity on the voltage could be ignored and the effect of the ACD is obvious. Moreover, there is a linear decrease between the voltage and the thicknesses of the anode and cathode; and the anodecathode working height also has a significant effect on the voltage.

Compared with traditional methods, computational fluid dynamics–population balance model (CFD–PBM) simulations are much more efficient for the design of extractors. In this study, the CFD–PBM framework was established for a pilot-scale rotating-disk contactor. The Euler–Euler approach incorporated with the realizable k–ε model was used for the two-phase simulation. For droplet coalescence and breakage, predictive closures based on the model of Luo and Svendsen were employed for further verification. The species transport model was also solved to estimate axial mixing. The model was validated first by comparing the flow field with referenced particle image velocimetry data. Then the predicted key parameters of droplet diameter, dispersed-phase holdup, and Peclet number were compared with empirical correlations for a comprehensive validation. The results indicate that the predictive CFD–PBM is suitable for the design of extraction columns. Its average deviations on the three parameters are 15.7%, 12.9%, and 15.2%, respectively. The model also successfully predicts the regular variations of the droplet diameter and holdup with the rising agitation rate, which contribute to the validation.

Systematic results from molecular dynamics simulations of molten alkali chlorides (ACl) serials are presented in detail in this paper. The effects of temperature and cationic size on the structures and transport properties of molten salts have been investigated and analyzed. The local structures of molten ACl have been studied via the analysis of radial distribution functions and angular distribution functions. The coordination number of ACl decreases when ACl melts from solid and increases as cationic radius increases. Molten LiCl takes a distorted tetrahedral complex as the microconfiguration, while other melts have the tendency to keep the original local structure of the corresponding crystal. Temperature has no significant effect on the local structures of molten ACls. The results also show that the Tosi–Fumi potential predicts positive temperature dependences for self-diffusion coefficients and ionic conductivity, and negative temperature dependences for both viscosity and thermal conductivity of molten ACls. Ionic diffusivity decreases as cationic radius increases from LiCl to CsCl. The simulation results are in agreement with the experimental data available in the literature.

The potential to damage synthetic graphite is high during the pyrolysis of pitch/coke composite material in processing of carbon/carbon components. Exact modeling of heating patterns could optimize the preparation conditions in order to obtain high quality products. A capillary–cell model was built to evaluate the internal pressure resulting from volatile matter in green carbon blocks during carbonization. The theoretical model for heating patterns was proposed by considering the influence of heating rates on the internal pressure and the thermal stress during the heat-treatment procedure. The results showed that the theoretical heating rates were mainly controlled by mass transfer in the range 467–850 K and by heat transfer in other temperature ranges. The values calculated by the developed model were compared with the industrial results, and the validity of the proposed method for the prediction of heating patterns is evaluated.