A Novel Process for Recycling of Aluminum Dross Using Alkali Fusion

Abstract

Aluminum dross discharged from an aluminum production factory can react with water and emit hazardous gases such as hydrogen and ammonia causing serious environmental pollution. Thus, it becomes necessary to recycle the by-products to avoid such problems. In this study, the feasibility of the alkali fusion process to convert the dross into benign and functional material was investigated. The effects of fusion temperature, dross/NaOH ratio, and the heating time on the amount of gas removed from the dross and the soluble contents of Si and Al in the fused dross were examined. Synthesis of zeolite–A from the fused dross was performed by reacting with sodium silicate. The optimum condition to dissolve the minerals Al and Si and maximize the generation of gases was a fusion temperature of 400°C, the ratio of the raw dross to NaOH of 1.0, and the heating time of 3 h. The fused dross can be converted into zeolite-A product with a high cation exchange capacity (3.22 mmol·g−1) by reacting with sodium silicate solution while generating as much gas as that generated in distilled water. These results demonstrate the applicability of the alkali fusion process to recycle the aluminum dross waste generated from an aluminum industry into value-added material, thus contributing to the circular economy while reducing the environmental impact.