Environmental Impact and Carbon Footprint Assessment of Rare Earth Recycling Technologies - A Case Study of Recycling Yttrium and Europium From Phosphor
| Autor: | Chien-Hung Kuo, 郭建宏 |
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| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 Rare earth elements are the key raw materials of high-tech industries; however, their mining have long been creating lots of environmental impacts, such as soil erosion, destruction of vegetation and water pollution, etc. Due to the global shortage of rare earth resources, it will be difficult to sustain their long-term supply. Thus, in recent years, rare earth and their supply has become hot issue. Many industrialzed countries have regarded rare earth resources as important strategic resources for economic growth. In light of the facts mentioned above, this study intends to explore the environmental impact and carbon footprints of recovering Yttrium and Europium from phosphor. Two extraction recovery methods, namely acid extraction and solvent extraction, were selected for analysis and comparison. Two LCA commercial softwares were applied and two functional units, same ammounts of phosphor and specific recovery concentrations of Yttrium and Europium, were used. Regarding the acid extraction method, two acidic solutions (H2SO4 and HCl) in two different temperatures (60 ℃, 90 ℃) were used, which were compared with solvent extraction method. Results of acid extracton method showed that the carbon emissions of raw material stage is 58 kgCO2-eq, and the carbon emissions of manufacturing stage are 9.76 kgCO2-eq, 10 kgCO2-eq; 9.26 kgCO2-eq and 9.54 kgCO2-eq for H2SO4, 60 ℃, H2SO4, 90 ℃, HCl, 60 ℃ and HCl, 90 ℃, respectively. For solvent extraction method, the carbon emissions of raw material stage and manufacturing stage are 69 kgCO2-eq and 10.6 kgCO2-eq, respectively. After comparing the carbon emissions of two extraction methods, it is found that although acid extraction method has lower carbon footprints, however, solvent extraction method has much higher extraction efficiency. These results may be used for crafting strategies in implementing life cycle management of rare earth resources for realizing a sustainable use of rare earth resources. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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