Mechanism and Kinetic Study on Ultrasonically Enhanced Reduction Leaching of Zinc Suboxide

The leaching process represents the primary bottleneck in achieving efficient utilization of zinc suboxide, thereby resulting in a squandering of germanium resources. In this Article, the kinetic mechanisms of conventional and ultrasonic enhanced reduction leaching of zinc suboxide were investigated while optimizing the leaching conditions. The optimized conditions for the ultrasonic enhanced reduction leaching process were found to be 358 K, FeS of 0.6% zinc suboxide mass, and 300 W of ultrasonic power. The leaching efficiency of germanium can reach 91.34% under these conditions, exhibiting an improvement of 8.51%, compared with conventional conditions. Moreover, the Fe³⁺ concentration in the leaching solution is consistently maintained at ∼15 mg/L, satisfying the requisite criteria for germanium precipitation. Moreover, both the conventional and ultrasonic leaching processes obey the Drozdov kinetic model and are governed by internal diffusion. The difference, however, is that, under ultrasonic conditions, the activation energy of the reaction is reduced by 2.05 kJ/mol, the self-resistance coefficient is smaller, the reaction rate is faster, and the germanium leaching efficiency is higher than under conventional conditions. Ultrasonically enhanced FeS reduction leaching disrupts the encapsulation of silica gel and lead sulfate, shattering large dust grains and reducing the surface tension and viscosity of the solution, thus reducing the energy barrier to the leaching of germanium-containing components and improving the kinetics. The present study elucidates the kinetic laws governing conventional and ultrasonic processes, thereby offering guidance and a theoretical foundation for enhancing the germanium leaching efficiency in zinc suboxide. These findings hold significant implications for maximizing the utilization of germanium resources and advancing the development of the germanium industry.