The properties of the mixtures used in hot metal dephosphorization, such as solid and liquid fraction phases, CaO and FeO activity and viscosity, are determinant for the process efficiency. The ...influence of these properties on hot metal dephosphorization were studied for CaO–FeO–SiO2 mixtures. The experiments were carried out at 1400 °C, in MgO-C crucibles, where the mixtures were added to the hot metal. Metal samples were taken at different times to measure the variation of phosphorus (P) content over time. The initial mixtures and final slags properties were determined by computational thermodynamics software FactSage 7.2. A parameter named Dephosphorization Factor (FDeP), that measures the efficiency of the initial mixtures and final slag, in hot metal dephosphorization was used. It was found that the FDeP presents a high correlation (R2) with the dephosphorization efficiency and can be used to predict which slag will be the most efficient.
Abstract Over the last decades, the capability of a desulfurizing mixture to remove sulfur has been widely studied. The hot metal desulfurization efficiency represents the percentage of sulfur ...removed from the bath and the development of parameters that predict the process efficiency is fundamental for selecting the best desulfurization mixture without the need for experimental tests. Therefore, this research aims to develop a new parameter to predict the hot metal desulfurization mixture efficiency, which was called the desulfurization factor (FDeS). Desulfurizing mixtures from CaO-Fluorspar and CaO-Sodalite systems were used for this purpose. The phases present in the heating of the mixtures at 1400°C as well as the liquid and solid percentage were determined by ThelmoCalc software. These data were used in the desulfurization factor construction. Experiments were carried out in an electric resistance furnace with mechanical stirring. Different mixtures from these systems were added in molten hot metal at 1400°C. Sampling was made to measure the sulfur content variation with time. It was possible to apply the desulfurization factor to the proposed mixtures and to determine the influence of the solid and liquid phases on the desulfurization efficiency.
Abstract Synthetic slag has been added during BOF tapping in order to modify the physicochemical properties of resulting slag with the aim of assessing the influence on inclusion density, composition ...and size distribution. Viscosities and activities of slag oxides were calculated by FactSage 7.2, using the FToxid database and Viscosity module. All heats were treated under vacuum in an RH degasser for 15 minutes. A comparative analysis of top slags with two levels of FeO+MnO (> 10% and ≤ 10%) was carried out. The higher level of FeO+MnO led to almost thrice more inclusion than the lower level. Top slags after treatment with synthetic slag brought the best result of inclusions features thanks to their higher CaO activity, lower viscosity and lower activity of Al2O3. These heats presented smaller inclusions and lower initial inclusion density at ladle arrival at RH. Based on these evidences, top slags with synthetic slags added during the tapping and FeO+MnO content ≤ 10% conferred the best condition in steel cleanliness.
The braking energy in diesel-electric locomotives is typically wasted into resistors. A more energy-efficient way is to store and recycle such energy. Thus, this article proposes a multiport power ...conversion system as the core of a hybrid energy storage system, based on Lithium-ion (Li-ion) batteries and supercapacitors (SCs). In such configuration, SCs act as a buffer against large magnitudes and rapid fluctuations in power, thus reducing current stresses in the battery system. Unlike other alternatives, this solution uses the recovered energy to supply only auxiliary loads, while the diesel generator keeps powering traction motors. As a consequence, the required energy storage capacity for the system is considerably reduced, which reflects reduced cost and volume. Further, the proposal can be used to retrofit existing systems and can also be adapted for other types of locomotives. To validate the proposed concept, a 7.6-kW scaled-down prototype was implemented using electric motors to emulate the locomotive power-train structure. Experimental results demonstrate the effectiveness of the power management strategy under different operating scenarios.
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