Chloride molten salt-mediated one-step electrochemical recycling of tellurium from copper(i) telluride

Abstract

Copper(I) telluride (Cu₂Te) derived from the copper smelting process is an important source of tellurium (Te) recovery. However, conventional Te extraction relies on acid and alkaline leaching processes, which generate toxic waste and involve prolonged processing steps. Developing green and efficient Te recycling methods is therefore essential to improve production efficiency, shorten process flow and reduce environmental pollution. In this work, a chloride molten salt-mediated, one-step electrochemical approach for the separation and extraction of Te is proposed. The thermodynamic calculations and molten salt property analysis demonstrate that the molten LiCl–KCl is an ideal mediated electrolyte for Cu₂Te recycling. The electrochemical investigations further confirm that the controlled cathodic Cu reduction and anodic Te oxidation can be achieved at a relatively negative potential (≤−1.7 V vs. AgCl/Ag). The systematic optimization of electrolysis conditions indicates that the complete separation and recovery of Te and Cu are realized by controlling the cell voltage (∼2.4 V), electrolysis temperature (∼420 °C), and duration (≥3 h). Moreover, the purity of Te and atom economy obtained by this method can reach 99.98% and 100%, respectively, with a recovery efficiency of 93.0% and an energy consumption of only ∼1.24 kWh per kg of Te. Compared to traditional hydrometallurgical processes, this proposed approach shortens workflows, reduces Te loss, generates no waste, co-produces high-value metallic Cu and reduces production costs. Ultimately, this work provides a clean, waste-free and sustainable strategy for treating Cu₂Te from spent copper telluride slag.