Aluminum, as a lightweight core industrial metal, is widely used in transportation, construction, electronics and power fields, and global aluminum production capacity continues to expand. The production of primary aluminum requires three major processes: bauxite mining, Bayer process for preparing alumina, and Hall Elute electrolysis. The electrolysis process is a highly energy consuming process, consuming tens of thousands of megajoules of energy per ton of primary aluminum electrolysis, accompanied by a large amount of greenhouse gas emissions such as carbon dioxide. In contrast, recycled aluminum only requires pre-treatment, remelting, refining, and casting of aluminum waste, without the need to reduce alumina. Theoretically, it can save the vast majority of energy and is the most important lever for the low-carbon transformation of the global aluminum industry. According to BIR statistics from the International Bureau of Recycling, recycled aluminum can achieve 90-95% energy savings compared to primary aluminum. EU regulations require that the material recycling rate for scrapped vehicles must reach 95%, further promoting the development of the waste aluminum recycling industry.

Despite the natural low-carbon advantages of recycled aluminum, the thermal efficiency of the smelting furnace is not ideal under actual factory operating conditions. Industrial tests have shown that the effective thermal efficiency of gas melting furnaces is only 26-29%, with over 70% of the input energy lost in various forms of heat loss, resulting in serious energy waste and additional carbon emissions. Different melting furnace equipment, raw material composition, and waste heat utilization levels can cause significant differences in unit product energy consumption and carbon footprint. Many companies only focus on the direct consumption of fuel and electricity, ignoring the indirect carbon emissions brought by upstream raw materials, especially the significant impact of the proportion of primary aluminum ingots in the ingredients on the overall carbon footprint, resulting in misjudgment of the low-carbon attributes of products.

The research focuses on the recycled aluminum casting workshop of SAPA Heat Treatment Company, which produces 80000 tons of aluminum rolled slabs annually. The raw materials include purchased primary aluminum ingots, internal waste materials returned from the factory, and externally recycled waste aluminum. The study collected on-site measured data from a complete factory in 2011 and conducted full process energy flow accounting based on quality energy conservation. The Cradle to gate life cycle assessment was used to systematically calculate the comprehensive energy consumption and carbon footprint of each ton of aluminum plate blank. The performance differences between oxygen fuel melting furnaces and induction furnaces were compared, and the impact of different raw material formulations on environmental indicators was quantified to explore the potential for energy conservation and carbon reduction in workshops. This study is based entirely on real industrial field data and has high reference value for process optimization in the recycled aluminum industry.