Abstract:Assessing and accounting for material consumption and environmental impact are necessary to measure environmental externalities of the aluminum industry and to construct an ecological civilization. In this research, life cycle assessment (LCA) theory was used to assess the environmental impact of primary aluminum based on the lime soda Bayer process and different power generation modes, and the sources and distributions of the four selected impact categories were analyzed. The results show that, (1) Negative environmental impact of aluminum industry generally occurs from alumina extraction, carbon anode fabrication and electrolysis, particularly electrolysis and alumina extraction. Primary energy demand (PED), water use (WU), global warming potential (GWP) and freshwater eutrophication potential (FEP) are main environmental impact categories. (2) The environmental load with thermal power is higher than that with hydropower, e.g., for the former, the greenhouse gas emission coefficient of 21800 kg CO₂ eq/t (Al) will be generated, while for the latter, 4910 kg CO₂ eq/t (Al) will be generated. (3) Both power mode methods reflect the energy structure, whereas direct emissions reflect the technical level, indicating the potential for large energy savings and emission reductions, and some policies, related to clean power, energy efficiency and technological progress, should be made for emission reduction.

Key words: primary aluminum; environmental impact; life cycle assessment; emission reduction potential