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This paper introduces a numerical model of an electromagnetic rotary stirrer based on the finite-element model. Such stirrers are used to improve the quality of continuously cast steel, particularly billets and blooms. The method determines the magnetic flux density profile and compares it to experimental measurements. In addition, it calculates the Lorentz force field as a function of the stirrer position, the current applied, and the frequency. The stirrer position at the end of the mold affects the profile symmetry of the force, creating a component of the force. With this model, it will be possible to simulate the fluid dynamics effects in the molten steel.

This paper presents an initial part of a project devoted to the recycling of mill scale in the form of selfreducing briquettes. First chemical and morphological characteristics of mill scale were investigated and next its gaseous reduction behavior was studied by thermogravimetry. The chemical characterization showed that wustite is the major constituent of this waste matter, with small amounts of magnetite, hematite and metallic iron. The microscopic examination of the scale revealed its complex and layered microstructure with three distinct zones. The outer layer is relatively thin and porous. It is mainly composed of hematite and magnetite. The intermediate layer is made of the dense, columnar grains of wustite. The inner layer is a very porous wustite. The gaseous reduction by carbon monoxide has a topochemical character regardless of initial morphology of scale and, depending on temperature and reducing gas composition it produces a porous iron or the iron whiskers. The unreacted shrinking core model with one interface fits quite well the kinetic data and the activation energy of reduction is about 80 kJ/mol.

One of the functions of secondary refining in steelmaking is to remove non-metallic inclusions produced through deoxidation of the steel bath during the process. Removal of these inclusions occurs in three fundamental stages: flotation, separation and dissolution of the inclusions in supernatant slag. Given that dissolution is subject to the action of slag, this study aims to clarify the inclusion absorption capacity of industrial slags and factors that influence slag properties in absorbing inclusions, as well as the impact of each factor on the cleanliness of the steels analyzed. To that end, the results of industrial steel and slag samples collected during the different stages of secondary refining were analyzed. The amount and chemical composition of the inclusions was determined by SEM/EDS (scanning electron microscopy coupled with energy-dispersive spectroscopy). The chemical composition of slag samples was measured by XRF (X-ray fluorescence) and subsequently submitted to thermodynamic simulations using FactSage 6.4 software. Calculations were made with the SlagViscosityPredictor, which uses FactSage 6.2 software. This made it possible to establish the chemical composition and proportion of the solid phase in the slags and inclusions, as well as the effective viscosity of the slags. The efficiency of absorption inclusion by the industrial slags was found to be greater in the presence of high thermodynamic driving force between slags and inclusions, low slag effective viscosity and when inclusions were not liquid.