In this study, a Life Cycle Inventory (LCI), based on Emergy Analysis, was conducted for the Chinese aluminum industry. The following four process stages were considered: (1) deposit formation; (2) production processes (such as bauxite mining, alumina refining, electrolysis & ingot casting, manufacturing and fabrication); (3) end use; (4) aluminum recycling process. Unit Emergy Values (UEVs), a measure of resource use efficiency, were computed along every stage of China's aluminum production system and compared with the corresponding UEVs for the USA. Although the UEVs in China were higher than those of USA, the observed gaps narrowed along the aluminum production chain from bauxite mining to end use. Subsequently, the change of all aluminum outputs UEVs were evaluated considering the change of recycling rates. The effects of changes in domestic production and import policy of aluminum outputs on aluminum production efficiencies (UEVs) were also considered. This work found, in terms of providing the best overall increase in efficiency, Restricting bauxite mining and importing bauxite resulted the best option, which provided the best overall efficiency increase, as shown by decreases in UEVs. The impact on overall production efficiencies of increasing the recyclable aluminum quantity, by including a higher recycling amount, was tested. A reduction of 2.41E+09 sej/kg in bauxite, 1.76E+11 sej/kg in alumina, 3.24E+11 sej/kg in aluminum ingot, 8.96E+12 sej/kg in recycled aluminum and 3.84E+12 sej/kg in aluminum product were found, fixing the recycling rate up to 100% and doubling the total amount of home and prompt scraps. Finally, results show that increased recycling provides also increased energy and material efficiencies throughout the production process. These results reveal that the most ideal production roadmap for China would consist in recycling as much aluminum as possible. This, in turn, demonstrates that aluminum trash would be the real treasure for China.
Trash or treasure? Prospects for full aluminum chain in China based on the recycling options
Casazza M
2018-01-01
Abstract
In this study, a Life Cycle Inventory (LCI), based on Emergy Analysis, was conducted for the Chinese aluminum industry. The following four process stages were considered: (1) deposit formation; (2) production processes (such as bauxite mining, alumina refining, electrolysis & ingot casting, manufacturing and fabrication); (3) end use; (4) aluminum recycling process. Unit Emergy Values (UEVs), a measure of resource use efficiency, were computed along every stage of China's aluminum production system and compared with the corresponding UEVs for the USA. Although the UEVs in China were higher than those of USA, the observed gaps narrowed along the aluminum production chain from bauxite mining to end use. Subsequently, the change of all aluminum outputs UEVs were evaluated considering the change of recycling rates. The effects of changes in domestic production and import policy of aluminum outputs on aluminum production efficiencies (UEVs) were also considered. This work found, in terms of providing the best overall increase in efficiency, Restricting bauxite mining and importing bauxite resulted the best option, which provided the best overall efficiency increase, as shown by decreases in UEVs. The impact on overall production efficiencies of increasing the recyclable aluminum quantity, by including a higher recycling amount, was tested. A reduction of 2.41E+09 sej/kg in bauxite, 1.76E+11 sej/kg in alumina, 3.24E+11 sej/kg in aluminum ingot, 8.96E+12 sej/kg in recycled aluminum and 3.84E+12 sej/kg in aluminum product were found, fixing the recycling rate up to 100% and doubling the total amount of home and prompt scraps. Finally, results show that increased recycling provides also increased energy and material efficiencies throughout the production process. These results reveal that the most ideal production roadmap for China would consist in recycling as much aluminum as possible. This, in turn, demonstrates that aluminum trash would be the real treasure for China.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
