Kinetics of indium separation and recovery from In–Sn alloys in ITO waste target products via vacuum evaporation

Abstract

The environmentally friendly recycling of ITO waste material to regenerate indium resources is crucial for sustainability. The hydrogen reduction process, particularly the green and low-carbon technique of vacuum distillation, is crucial in the production of In–Sn alloys. However, a thorough examination of the mechanics underlying its evaporation throughout this process has yet to be performed. These mechanics are investigated in the present study for 92In–8Sn alloys under specific conditions, including temperatures between 1173 and 1373 K, pressure of 5 Pa, and crucible depth of 25 mm. The relationship between temperature and the rate of volatilization is mathematically represented as ω = e(a+b∙T). Furthermore, the equation ω = A2 + (A1-A2)/(1 + e(h-h0)/dh) was used to predict the dependency of the volatilization rate on crucible depth, ranging from 25 to 65 mm at 1323 K and 5 Pa. The mass transfer coefficients for the alloy at different temperatures were calculated, and a theoretical kinetic model for evaporation behavior indicated that vapor-phase mass transfer is the limiting step in the process of vacuum distillation of this alloy. This study presents a theoretical basis for the retrieval of In from the In–Sn alloy using vacuum distillation.