Determination of the Fe3+/$${\varvec{\Sigma}}$$Fe Ratio in Synthetic Lead Silicate Slags Using X-Band CW-EPR

Abstract

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.

Magnetic properties of the mononuclear iron (III) complexes with biphenyl‐disubstituted Schiff base ligand: EPR and SQUID study

“…Since both the LS and HS states of iron (III) species are paramagnetic, the EPR spectroscopy is a very useful tool to study electronic states in the iron (III) systems. [ 14 ] Traditionally, magnetic properties are studied with direct solid‐state measurements—SQUID (superconducting quantum interference device) magnetometry [ 15 ] and indirect solution measurements—the Evans method (nuclear magnetic resonance ‐ NMR).…”

Towards more realistic simulations of microstructural evolution in oxidic systems

“… Diffusion data: at the moment we used orders of magnitude for the diffusion coefficients, because there is not much diffusion data available for oxidic systems.  To investigate the influence of the partial pressure of oxygen, also more data on the ratios of Fe 3+ over Fe 2+ [58,59] are very relevant in various slag matrices.…”

Enhanced photocatalytic activity of Fe@UiO-66 for aerobic oxidation of N-aryl tetrahydroisoquinolines

“…Electron paramagnetic resonance (EPR) was used to analyze the dispersion of iron sites. 44,45 The EPR peak at g = 4.3 is assigned to high-spin Fe(III), which mainly exists in highly isolated Fe(III) in tetrahedral and distorted tetrahedral coordinations. The signal at g = 2.0 is ascribed to isolated Fe(III) in a high-symmetry octahedral coordination or Fe x O y oligomers (Fig.…”