Development of an Analytical Technique to Quantify Cr²⁺ and Cr³⁺ in Metallurgical Slags

Knowledge of thermodynamic properties of chromium oxides in molten slags is very important for the optimization of the steel making processes of stainless and high-alloying steels as well as the processes of chromium ores. Despite this importance, the thermodynamic data for chromium oxides at steel making temperatures are still too scarce to meet the demand. Only a few experimental studies are found in the literature.[1‐5] Chromium exists in the form of ions, namely, Cr²⁺, Cr³⁺, and even Cr⁶⁺ in oxide solutions. The fractions of these irons depend not only on temperature but also on the chemical potentials of chromium and oxygen in the system. In the slags of steel making, chromium would mostly take the form of Cr²⁺ and Cr³⁺. The difficulties associated with maintaining the fractions of these ions and accurate determination of the same are among the main reasons for the scarcity of thermodynamic data. For example, Cr²⁺ easily reacts with lixiviating impregnant and forms intermediates in wet chemical analysis due to its unstable nature.