Effect of mechanical activation on the kinetics of extracting indium from indium-bearing zinc ferrite

The synthetic indium-bearing zinc ferrite (IBZF) was mechanically activated by a stirring ball mill and subsequently studied for the leaching behavior and kinetics of extracting indium from IBZF. The effect of the change in crystalline phase, lattice distortion, particle size, specific surface area and morphology introduced by mechanical activation (MA) was also investigated. The activated IBZF showed different physicochemical characteristics and was found to be easier to dissolve in sulphuric acid than the unmilled sample. MA enhanced the leaching reactivity of IBZF. When IBZF was mechanically activated for 30 and 60 min, the activation energy decreased from 68.8 kJ/mol to 54.4 and 44.7 kJ/mol, respectively. The leaching process of unmilled IBZF was controlled by chemical reaction, but became the hybrid controlled process after MA. The reaction orders of the unmilled, activated for 30 and 60 min IBZF dissolution with respect to H2SO4 concentration were 0.69, 0.58, and 0.54, respectively.