An Effective Process for Selective Separation of Cu–Zn Film from Steel Tire Cords in Ammonia Solution

The Cu–Zn film on the discarded steel tire cords (STCs) makes them challenging to regenerate by an electric arc furnace (EAF) process. The traditional removal technology by ammonia leaching was limited by the long leaching time and low leaching efficiency. To address this issue, a clean and highly efficient technology is proposed in this study to separate the Cu–Zn film from the STCs in the ammonia solution by electroleaching. The electrochemical dissolution behaviors of Cu, Zn, and Fe were systematically investigated, and the results show that Cu and Zn can be selectively electrodissolved while Fe remains stable in the ammonia solution. Various parameters, including electroleaching cell voltage, ammonia concentration, leaching temperature, and stirring rate, were investigated and optimized to enhance the removal ratios of Cu and Zn from the STCs. After electroleaching at 1.5 V for 300 s with 250 rpm in a 2 M ammonia solution at 30 °C, the removal ratios of Cu and Zn reached 92.9% and 95.1%, which met the element requirement for the regeneration of STCs. Compared with the effect of ammonia leaching, electroleaching presents a high leaching rate and efficiency. This work presents potential applications for the lifecycle management of end-of-life STCs.