RESUMO
Secondary aluminum ash (SAD) disposal is challenging, particularly in developing countries, and presents severe eco-environmental risks. This paper presents the treatment techniques, mechanisms, and effects of SAD at the current technical-economic level based on aluminum ash's resource utilization and environmental properties. Five recovery techniques were summarized based on aluminum's recoverability in SAD. Four traditional utilization methods were outlined as per the utilization of alumina in SAD. Three new utilization methods of SAD were summarized based on the removability (or convertibility) of aluminum nitride in SAD. The R-U-R (recoverability, utilizability, and removability) theory of SAD was formed based on several studies that helped identify the fingerprint of SAD. Furthermore, the utilization strategies of SAD, which supported the recycling of aluminum ash, were proposed. To form a perfect fingerprint database and develop various relevant techniques, future research must focus on an extensive examination of the characteristics of aluminum ash. This research will be advantageous for addressing the resource and environmental challenges of aluminum ash.