A Kinetic Study of Vanadium Dissolution During Acetic Acid Leaching of Steel Making Converter Slag

Steelmaking slags are known as the secondary product of steel making process. Regarding the high rate of slag production and the existence of a noticeable amount of toxic and valuable metals such as vanadium in this material; recovery of vanadium from this product is necessary. In this study, steel making converter slag (containing about 1.96 wt.% V2O5) was ground to a mean size of 85 μm, and recovery of vanadium was carried out using acetic acid leaching. The effects of time (in the range of 0 to 120 min) and temperature (in the range of 0 to 80 ⁰C) in fixed acetic acid concentration (1 molal) and solid to liquid weight ratio (one gram slag in 200 ml) on the leaching process were investigated. The results showed that the increase in time and decrease of temperature (activation energy was equal to -11.4 kJ/mol) increases vanadium leaching efficiency. Maximum leaching efficiency was reached at 0 ⁰C and 90 min. Kinetics studies showed that heat diffusion through the solid layer is the controlling step of vanadium dissolution in acetic acid. Furthermore, thermal conductivity (ka) decreases by increasing temperature (ka=21877.6/T3), so the heat moves away from the reaction zone to the particle's surface at a slower rate.