Assessing the Supply Risk and Environmental Impacts of Rare Earths Oxides with Criticality and Life Cycle Assessment Methodologie

The unique properties of rare earth elements (REE) made them very important to modern society development. At the same time, concerns also arise for topics like difficulties in mining, the environmental impacts of mining and refining, and the dominance of mining activity by China. It is necessary to assess the supply risk of REEs, since a stable raw material supply is essential for the development of end-use products that incorporate REEs in their important components. As REEs are critical to clean energy technologies, it is also important to understand the environmental impacts resulting from their production, and factors that influence such impacts. Moreover, among the handful of life cycle assessments (LCA) on REEs, all of them are lacking the information to use localized inventory database where the rare earths are mined, and most of them are based on bastnasite/monazite sites that primarily produce light REEs, with few assessing sites producing mostly heavy REEs.;This dissertation introduces an improved supply risk assessment method for REEs, with introduction of new indicators and new calculation methods, and addresses the gaps in current LCA studies for REEs by conducting two detailed LCA for rare earth oxides (REO) produced in Inner Mongolia and southern China. In the supply risk assessment, the environmental Kuznets curve were applied to capture relationship between the mining industrial development and social development. A new method is proposed to calculate the geopolitical risk of REEs by incorporating concentration of mining countries and their political stability index. Contributions are made to existing LCAs by investigating sites producing heavy rare earth oxides (REOs) and applying the Chinese Life Cycle Database (CLCD) to conduct the inventory analysis. Province-level data for electricity generation are acquired through Ecoinvent 3 database to conduct a temporally dynamic LCA with grid mix change. Twelve impact categories were examined using Impact 2002+, USEtox 2.01 and IPCC in life cycle impact assessment.;For supply risk calculations, results show that supply risk of REEs is highly correlated with the concentration of the production market. During the time when China is being the dominant producer with over 90% of world production, the fluctuation of supply risk is almost solely depend on the change of China's policies. For LCA studies, results show that for extraction of light REOs in Inner Mongolia, mining, calcination, and extraction and roasting stages contribute significantly to almost every environmental impact category. And for extraction of heavy REOs in southern China, mining and extraction are the two process stages that contribute most to the impact categories. In both of the two LCAs, chemicals used in production are responsible for a large share of energy consumption and environmental pollutions. Electricity used are influential for energy use and global warming potential.