(Theme session) Academic exchange session in English

[1301-08-06] Recovery of Copper and Zinc from Simulated Acid Mine Drainage using Scrap-based Aluminum-Iron (Al-Fe) Bimetallic Particles

○Dayle Tranz Dano^{1[Student presentation: Doctoral course]}, Ilhwan Park¹, Mayumi Ito¹, Vannie Joy Resabal², Carlito Tabelin² (1. Hokkaido University, 2. Mindanao State University - Iligan Institute of Technology)

司会：芳賀　一寿（秋田大学）

Keywords:secondary metal resources, acid mine drainage, metal recycling, circular economy

The global transition to green technologies is significantly increasing the demand for critical metals, such as copper and zinc. With primary reserves under pressure, sustainable secondary sources are urgently needed. Acid mine drainage (AMD)—a highly acidic, metal-rich effluent from mining—is often viewed as an environmental hazard, but it also presents an opportunity for metal recovery. This study investigates the use of locally sourced recycled aluminum scrap to synthesize Al-Fe bimetallic materials for recovering Cu and Zn from synthetic AMD. The results revealed that Al/Fe bimetallic materials can achieve a maximum recovery of 100% of Cu and 98% of Zn, and both time and bimetal dosage play a role in the recovery. Previous studies have reported that the mechanism of metal recovery by Al-Fe bimetals is electrochemical reduction, explaining the observed faster and preferential recovery of the more noble copper (E⁰= 0.34 V) over Zn (E⁰= -0.76 V).SEM-EDX analysis confirmed Cu deposition on the bimetal surface and exposed Al, indicating three possible reduction pathways: (1) direct reduction by Al, (2) by Fe, and (3) via galvanic interactions in the Al/Fe system. Furthermore, a significant increase in pH from 2.12 to 5.72 was recorded after the process. Although the increase in pH can sequester metals as hydroxide compounds, neutralization experiments revealed that 100% recovery of Cu and Zn is only possible at a pH of >9. This strengthens the claim that the mechanism of metal recovery is electrochemical reduction, mainly driven by the galvanic interaction between Al and Fe. These findings suggest that scrap-based Al-Fe bimetallic materials offer a promising, sustainable technology for simultaneous metal recovery and AMD remediation, thereby promoting sustainability and the circular economy.