Kinetics of the leaching of mechanically activated berthierite,boulangerite and franckeite

In this study, changes in surface area, morphology and leachability of antimony from mechanically activated berthierite—FeSb₂S₄, boulangerite—Pb₅Sb₄S₁₁ and franckeite—FePb₅Sn₃Sb₂S₁₄ by a high-energy planetary mill were investigated. It appears that a selective extraction of antimony from these complex sulphosalts in alkaline solution of sodium sulphide is positively affected by mechanical activation. The influence of milling on mineral particle size and shape was studied by scanning electron microscopy. The temperature dependencies of berthierite alkaline leaching were investigated in an interval of 323–363 K. Resulting experimental activation energies E _a were 0.11 and 6.78 kJ mol⁻¹ for mechanically activated berthierite due to a break of Arrhenius plot. The values E _a are characteristic for a process controlled by diffusion as the rate-controlling step of leaching reaction.