Iron and chromium sulfates from ferrochromium alloy for tanning

In this study we investigated the production of soluble iron and chromium sulfate complexes from high carbon ferrochromium alloy (Fe–Cr–HC) for utilization as a tanning agent. The temperature, sulfuric acid concentration, and the reaction time between Fe–Cr–HC and sulfuric acid were selected as independent variables for iron and chromium conversion. A quadratic response surface model was adjusted using the Box–Behnken statistical experimental design technique. The results obtained by solving multi-objective optimization problem have shown about 98.6–100% Cr and 86.9–89.1% Fe conversions. Perchloric acid and ammonium sulfate additions were investigated in order to determine the system limitations. The results have showed that an increase of perchloric acid concentration decreased the quantity of soluble chromium and iron compounds, while an ammonium sulfate addition improved the conversion of chromium up to 100%.