Eco-friendly H2O2 leaching for noble-metals Re and W selective recovery from waste thermoelectric materials. (1st October 2020) - Chen, Xi
Graphical abstract: Highlights: Recover tungsten and rhenium from waste thermocouple wire was studied. Recovery system was selected based on waste characterization. Optimum leaching conditions are 9.79 mol/L H2 O2, L/S ratio of 20:1, at 343 K for 7 h. Leaching kinetics was studied and a leaching model was suggested. 99.3% of WO3 and 98.6% of NH4 ReO4 obtained under optimum parameters. Abstract: The study focuses on the recycling of rhenium and tungsten from waste thermoelectric materials, typically waste thermocouples, using an eco-friendly process. By analyzing the structure and composition of raw materials and combining the concept of green development, the reaction solution and leaching system in hydrometallurgical recovery system was selected. The optimum leaching conditions were determined by studying the concentration of solvents, reaction temperature, liquid–solid ratio and reaction time. The optimum leaching conditions were obtained at a temperature of 343 K with a concentration of H2 O2 at 9.79 mol/L, and a liquid–solid ratio at 20:1. The kinetic analysis of leaching process was carried out and a leaching model was suggested. The sample and reaction products were characterized by using XRD, SEM and other multiple detection methods. The results may also be applied to other waste thermoelectric alloys with different compositions serving as a reference in ecological design of future products.