Modelling and computer simulation of reagents diffusion in high temperature diffusion controlled heterogeneous reactions
Purpose: In this paper a computational method which takes into account convection in the melting metal and slag phases is discussed. Design/methodology/approach: A deterministic computational model of high-temperature heterogeneous reaction between metal and oxide melts has been developed. Findings: Transport of reagents and products of reaction occur simultaneously both by diffusion and by laminar natural convection of the melting metal and oxide fluxes. The convection-diffusion equations have been numerically solved by a finite-differences time-implicit discretization scheme. The model was implemented by program which had been written in C# language. The computations have been performed for desulfurization reaction between liquid metal and slag phases. Research limitations/implications: To verify the reliability of the model, the computed results have been compared with experimental data. The good agreement has been obtained. The numerical results agree well with the results which were found by two independent experiments. Originality/value: This computational model enables to obtain results, for example sulfur concentration changes along the x axis, which is very difficult, almost impossible, to get by experiment. Using this mathematical model allows to predict the distribution of elements in the metal during the refining process and to reduce expenses in selection of optimum process’ conditions, which provide the metal with required composition. This model can be used for quantitative analysis of the diffusion stage of the heterogeneous reactions.
Thermodynamic evaluation of phase equilibria in the CaCl2-MgCl2-CaF2-MgF2 system
The phase diagram of the CaCl2-CaF2-MgCl2-MgF2 reciprocal ternary system was calculated thermodynamically from available data on the common-ion binary subsystems and from available data on the CaCl2-MgF2 join. This join is very nearly quasibinary and divides the system into two quasiternary systems: the CaCl2-MgF2-CaF2 system with a ternary eutectic calculated at 724 +-5 °C and the CaC2-MgF2-MgCl2 system with a ternary eutectic calculated at 561 +-5 °C.
Trouble-shooting dual arch impressions.
Dual arch impression techniques enable the dentist to capture an impression of the prepared tooth, the opposing teeth and the occlusal registration in one procedure. This saves chair time and impression material.