Oxidation kinetics of vanadium-bearing LD converter slag by mechanical activation

Abstract

ABSTRACTA thermogravimetric investigation was performed to evaluate the kinetic and thermodynamic parameters and the influence of mechanical activation on oxidation of vanadium-bearing LD (Linz–Donawitz) converter slag. Results indicate that the particle size of d0.5 significantly decreased from 29 μm to 0.266 μm after activation, and the specific surface area based on the BET model increased from 1.324 m2/g to 3.289 mm2/g. Thermogravimetric investigations were separately performed at 650, 700, 750, 800, 850, 900, 950 and 1000°C. Two distinct stages in the oxidation process were identified. The first stage was controlled by nucleation and growth and the second stage was controlled by 3D diffusion. However, the first stage relatively contributed more to the entire process than the second stage. Kinetic study also reveals that mechanical activation exhibited a significant effect on the oxidation of LD converter slag. Mechanical activation significantly reduced the roasting temperature and shortened the roasting time. The corresponding apparent activation energy Ea and frequency factor A changed from 13.01 kJ/mol to 6.59 kJ/mol and 0.247 min−1 to 0.141 min−1 for unmilled and milled slags, respectively.