Water-assisted-mechanical activation of copper pyrometallurgical tailings for molybdenum leaching and selective removal of environmentally-hazardous elements

•Amorphous nano-mesoporous materials were obtained in 4-hours-hydro-activatied CSFT.•Water-assisted milling shortens the time required for the amorphous transformation.•Bound water formed leads to particles expansion effect.•Activation of CSFT significantly enhanced the leachability of Mo, As and HMs.•Tetrahedral/octahedral-Si defects/vacancies produced improved leaching kinetics.