2014 S.P. du Preez Cr VI Generation During Flaring of CO Rich Off Gas from Closed Ferrochromium Submerged Arc Furnaces s11663 014 0244 3

Ferrochromium (FeCr) is crucial for the production of stainless steel, yet during its production, small amounts of Cr(VI) are unintentionally formed, particularly during the flaring of CO-rich off-gas from closed submerged arc furnaces (SAF). This study aimed to quantify the formation of Cr(VI) during this process. A laboratory-scale simulation using a vertical tube furnace was conducted to investigate the effects of flaring temperature, particle size passing through the flare, and retention time in the flame. The results were analyzed using multiple linear regression (MLR), which revealed that retention time significantly impacts Cr(VI) conversion, followed by particle size and temperature. An optimum mathematical model emerged from the analysis, allowing predictions of Cr(VI) conversion in different scenarios. The worst-case scenarios identified realistic conversion rates of 2.7 x 10^-C0 2 and 3.5 x 10^-C0 1 pct, both of which are substantially lower than the currently unverified estimates of 0.8 to 1 pct used in environmental assessments for FeCr smelters. These findings contribute valuable insights into the environmental impacts of FeCr production and highlight the need for more accurate assessments of Cr(VI) emissions.