Alejandro Cruz-Ramírez

Thermodynamic modeling of the BaO-SiO2 and SrO-SiO2 binary melts

The evaluation of the thermodynamic properties and the phase diagrams for the binary BaO-SiO2 and SrO-SiO2 systems is carried out using a structural model for silicate melts and glasses. This thermodynamic model is based on the assumption that an addition of metal oxides to silica results in the depolymerization of the silicon-oxygen network, with a characteristic free energy change. A least squares optimization program permits all available thermodynamic and phase diagram data to be optimized simultaneously. In this manner, data for the above binary systems have been analysed and represented with a small number of parameters. The resulting equations represent the thermodynamic and phase diagram data for the alkaline-earth oxide-silica systems within error limits for most of the experimental data. In particular, the measured limiting liquidus slope, at XSiO2 = 1, is well reproduced.

Silver removal from molten lead through zinc powder injection

Abstract A silver removal process was carried out on a Pb–Ag alloy through zinc powder injection of three different sizes (3.55, 44.4 and 734.8 μm) with a top submerged lance using nitrogen as carrying gas. The higher silver removal was obtained for the zinc powder size of 44.4 μm, while the lowest silver removal efficiency was attained for the smaller particle size. The AgZn phase was detected in the slag for the 44.4 and 734.8 μm particle sizes by XRD, which was in agreement with SEM-EDS analysis. Experimental behavior was explained according to the melting and residence time of the injected particles.

Application of Computational fluid dynamic in aluminum refining through pneumatic injection of powders

Magnesium removal process from molten aluminum using particles of silica sand was studied from a hydrodynamic point of view using computational fluid dynamics (CFD). The gas-liquid flow was modeled by a model of the Euler type for both gas and liquid phase transport. Newton´s law of motion was used to describe the subsurface motion of injected solid particles from the calculated flow field in one-way coupling. The kinetics of the transitory reaction was described by using the model proposed by Ohguchi and Robertson for transitory reactions. The contacting method of reaction for silica particles of 75, 210 and 425 µm was established according to its dynamic interaction with the two phases flow. When the particle size was increased, the residence time increased as well; however, the efficiency for the transitory reaction was decreased. The reaction rate simulation showed a good agreement with experimental results reported in the literature.