No abstract

No abstract

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 mechanism study, 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 during the experiment. The fact that silver is present in the attached copper droplets in a smaller concentration than 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.

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.

The oxidation balance is arguably one of the most important parameters during pyrometallurgical processes. In many cases, iron is the most abundant multivalent element present in silicate slags. Within these molten oxide mixtures, the oxygen balance is dominated by the relative fractions of Fe 3+ and Fe 2+ present. Measuring the concentration of ferrous and ferric iron in quenched slags can provide useful information about the oxidation state of the liquid slag at the moment of freezing. These measurements are not always straightforward, especially in lead rich slags, such as present in modern secondary smelting processes. Building on previous work, this article aims towards a practical and reliable methodology for determining the Fe 3+ concentration in lead rich silicate slags using continuous wave electron paramagnetic resonance (CW-EPR). The method is demonstrated for different Fe 3+ /ΣFe ratios and a basic model is proposed that relates the slag composition to the EPR spectrum, optimized for a high-lead ternary PbO-SiO2-Fe2O3 slag.