Mechanism and kinetics study on ultrasonic combined with oxygen enhanced leaching of zinc and germanium from germanium-containing slag dust

•Ultrasonic is used to enhance the leaching process of germanium-containing slag dust.•Ultrasound combined with oxygen can obtain stronger oxidation ability.•The leaching rate of zinc and germanium in the UOL is 4.92% and 9.80% higher than that in the conventional CL, respectively.•The UOL leaching method can improve the kinetics and reduce the activation energy of the reaction.•The enhanced mechanism of UOL leaching is clearly explained.