| With the development of society and the progress of human civilization, material is playing a more and more important role. In recent years, the amount of magnesium alloys has been increased dramatically. As structural components, magnesium alloys used in transport field has a significant lightweight effect. The automotive industry has become the main driving force for the application of magnesium alloy. However, the traditional Pidgeon has always been considered to be an industry of "high energy consumption, high pollution". In recent years, with the improvement of production technology and the introduction of regenerative combustion technology, the consumption of resources and energy for primary magnesium production has significantly reduced, as the emissions of pollutants and other environmental issues are still uncertain. Therefore, a life cycle assessment for the primary magnesium and its alloy production has become an important task of scientific researchers.In the process of primary magnesium production, the consumption of materials and energy has a significantly reduced because of the introduction of regenerative combustion technology. Compared with 2005, the ratio of raw materials and primary magnesium reduces to 6.5 from 9.5 and the input of energy decreases by 35% in 2009. The author analyzed the principle of energy-saving of the regenerative combustion technology, on this basis, calculating the environmental loads of the primary magnesium production in 2009. The results show: compared to 2005, Abiotic Depletion Potential(ADP), Global Warming Potential(GWP), Acidification Potential(AP), Photochemical Ozone Creation Potential(POCP) and Human Toxicity Potential(HTP) of primary magnesium production in 2009 decreased by 28%, 26%, 31%, 26% and 18 %.Because of active chemical properties of magnesium and its alloys, they should be melted under the prodection of flux or gas. But those two processes both have a greater environment impact. For two typical magnesium alloy AM60 and AZ31, this paper made an environmental impact assessment ahout two different processes, flux and gas protection, compared the differences betweem them, found the major environmental pressures, and identified that one of the processes has a relatively smaller impact than the other. In addition, according to the results of accumulative environmental load by calculating primary magnesium, primary aluminum and alloy preparation, we found that the environmental load of primary magnesium production almost determined the total environmental load of alloy production.To some extent, high energy consumption and high pollution of the primary magnesium will restrict the development and application of magnesium and its alloys. Take the auto parts made by magnesium alloy as an illustration, this paper did an analysis on environmental impact of magnesium alloy, as was"from cradle to door" including the processes of producting, assemblying, using, disusing and recycling. The results showed that: raw materials production and usage of auto parts almost determined the life cycle environmental impact of magnesium alloys, the percentage of two phases were 25.2% and 64.2%, respectively.Take an example on flux protection for producing AM60 magnesium alloy, this paper combined with the actual situation of production, usage and recovery for auto parts made from magnesium alloy, constructed a transport model for magnesium scraps, calculated the environmental load for the recycling process of magnesium scraps, and compared the environmental impact betweet primary magnesium alloy and recycled magnesium alloy. Finally, take the functional units of auto parts made from magnesium alloy for example, as it included the process of production, assembly, usage, recovery and recycled, this paper assumed that there was 30% recycled magnesium alloy took the place of primary magnesium alloy, calculating the life cycle environmental loads for magnesium, did an analysis for the substitution to the whole life cycle process. |
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