Metal droplet entrainment by solid particles in slags : an experimental approach

This study investigates the origin of the attachment of metal droplets to solid spinel particles in liquid slags. Previous research hinted a reactive origin: the spinel particles form by a chemical reaction together with a new droplet or alongside a droplet that was already present in the system. In this study, a smelting experiment was used to investigate this hypothesis. For such a study of the mechanism, a simple chemical system was used to avoid complex reactions. However, performing smelting experiments in simple slag systems requires an adaptation of the previously developed experimental methodology, resulting in a new 'partial melting' methodology. During the experiment, the atmosphere of the system was first set as oxidative, to dissolve the metallic copper in the slag and then a reductive atmosphere was used to actuate the reaction. Moreover, Ag was added to the metallic phase to act as a tracer element. The results show that the amount and size of copper droplets increase over the duration of the experiment. The fact that silver is present in the attached copper droplets in a smaller concentration than in the master alloy in this study indicates that the origin of the attachment is not purely dispersive, and either a purely reactive or a dispersion-reaction combination is possible, which confirms the hypothesis

Quantification of the Fe3+ concentration in lead silicate glasses using X-band CW-EPR

The majority of the existing experimental techniques for determining the fractions of Fe3+ and Fe2+ in silicate glasses are based on X-ray or gamma-ray absorption. Materials with a high lead content are not suitable for these techniques because they strongly absorb such high-energy radiation. This work investigates the feasibility and precision of X-band CW-EPR as an alternative technique for the quantification of the concentration of Fe3+ in iron containing lead silicate glasses. This could be a viable alternative since it is based on the absorption of microwaves, which are not heavily influenced by the presence of lead. A practical and robust method using standards is proposed, based on the empirical relation between the concentration of Fe3+ species and the occurrence of two distinct features in the collected EPR spectra. It was found that EPR can indeed be used for the quantification of Fe3+ concentration in lead silicate glasses up until about 8 wt.% Fe2O3, depending on the lead content of the glass. A precision of about +/- 0.10 wt.% (2 sigma) was observed for two tested experimental set-ups. The quantification method proposed requires standards of known composition

Critical assessment of the applicability of the foaming index to the industrial basic oxygen steelmaking process

The goal of this work is to assess the applicability of the concept of a "slag foaming index" on industrial data. For this purpose, process data from the steel plant of ArcelorMittal Ghent are used. An acoustic measurement is used to identify the heats with high levels of slag foaming. A model based on process data is developed to estimate the slag's composition during the converter process. The results of this model, together with industrial data on the slag's end composition, are used as input to calculate the slag's viscosity, density, and surface tension. Subsequently, the calculated foaming indices are compared with the acoustic measurements from industry. No distinct link between the calculated foaming index and the slopping behavior of the industrial slag is observed. Furthermore, it is observed that the slag's viscosity is the dominant parameter in the foaming index for the industrial slags. In conclusion, it seems that the calculated foaming index cannot be used as a tool to identify foamy slags within the considered industrial context