Effect of mechanical activation on enhancement of carbothermal reduction of nickel slag

The effects of mechanical activation on particle size distribution, crystalline phase, morphology, and mechanical energy storage of nickel slag were studied. Then, the direct reduction experiments of mechanically activated nickel slag mixed with reducing agent graphite powder were performed under conditions of 873–1273 K and reduction for 30–70 min. The results show that after 12 h of activation, 90% of the nickel slag has a particle diameter less than 1.05 μm, and the total energy storage is 1790.4 kJ mol⁻¹. With the extension of the mechanical activation duration, the intensity of the diffraction peaks of the main crystalline phases Fe₂SiO₄ and Mg₂SiO₄ in the nickel slag decreases. Mechanical activation is also an effective means to enhance the reduction of nickel slag. With the extension of the activation time, the reduction effect of the nickel slag and metallization degree increase. After 12 h of mechanical activation, the nickel slag was reduced at 1273 K for 70 min, and the metallization degree of the reduced product could reach 83.12%.