Life-Cycle Assessment of the Production of Rare-Earth Elements for Energy Applications: A Review

Abstract

Rare-earth elements (REEs) are a group of 17 elements with similar chemical properties, including 15 in the lanthanide group, yttrium, and scandium. Due to their unique physical and chemical properties, REEs gain increasing importance in many new energy technologies and systems that contribute to reduce greenhouse gas emissions and fossil fuel depletion (e.g., wind turbine, electric vehicles, high efficiency lighting, batteries, and hydrogen storage). However, it is well known that production of REEs is far from environmentally sustainable as it requires significant material and energy consumption while generating large amounts of air/water emissions and solid waste. Although life-cycle assessment (LCA) has been accepted as the most comprehensive approach to quantify the environmental sustainability of a product or process, to date, there have been only very limited LCA studies on the production of REEs. With the continual growth of renewable energy and energy efficient technologies, global production of REEs will increase. Therefore, reducing environmental footprints of REE production becomes critical and identifying environmental hotspots based on a holistic and comprehensive assessment on environmental impacts serves as an important starting point. After providing an overview of LCA methodology and a high-level description of the major REE production routes used from 1990s to today, this paper reviews the published LCA studies on the production of REEs. To date, almost all the LCA studies are based on process information collected from the operation of Mountain Pass facility in U.S. in 1990s and the operation of facilities in Bayan Obo, China. Knowledge gaps are identified and future research efforts are suggested to advance understanding on environmental impacts of REE production from the life-cycle perspective.

A Review of Rare Earth Mineral Processing Technology

“…6 Acid treatment and alkaline treatment are the two routes in chemical treatment. Both routes are employed to increase the REOs concentration with an estimation of 90% purities and remove impurities.…”

“…3 REEs are defined as the seventeen elements in periodic table which include a group of lanthanide series, scandium and yttrium element. [4][5][6] Scandium and yttrium have the disposition to co-exist with similar chemical properties such as other REEs. [7][8] It has to be noted that most of the rare earth (RE) metals are reportedly discovered within the earth's crust which consists of mixtures of various REEs along with some non-metals.…”

“…9 They are classified into 2 groups based on their atomic numbers: Light rare earth elements or LREEs and heavy rare earth elements or HREEs. 6 LREEs are also known as the 'ceries' which is within the atomic number ranging from 57-63 (La to Eu), whereas HREEs are known as 'yttrics' and it is within the atomic number ranging from 64-71 (Gd-Lu). In this regard, some scholars have classified both Scandium and yttrium into the heavy element category.…”

Economic assessment and carbon footprint of recycling rare earths from magnets: Evaluation at lab scale paving the way toward industrialization

“…Recycling of REE might provide environmental benefits compared to primary production (Binnemans et al., ; Schüler, Buchert, Liu, Dittrich, & Merz, ). Life‐cycle assessments (LCA) been conducted to evaluate the performance of waste treatment options (Laurent et al., ), yet only a few applications appear in the literature with respect to REE recycling (Amato et al., ; Bailey, ; Binnemans et al., ; Navarro & Zhao, ). They globally tend to confirm the hypothesis on the lower impact of secondary production compared to primary production (Jin, Afiuny, McIntyre, Yiha, & Sutherland, ), and offer perspectives for determining the most environmentally friendly recycling processing routes (Hu, Kuo, Huang, & Su, ).…”

Review of The Political Economy of Rare Earth Elements: Rising Powers and Technological Change, edited by Ryan David Kiggins, 2015 and Rare Earths Industry: Technological, Economic and Environmental Implications, edited by Ismar Borges de Lima and Walter Leal Filho, 2016.

“…However, the environmental impact section of the book relies heavily on a few non‐peer‐reviewed reports that appeared in the immediate aftermath of the 2010 crisis and mostly neglects more recent literature. For example, chapter 17 purports to give a state‐of‐the‐art review of the environmental impacts of rare earth mining, but does not discuss a single life cycle assessment study on the topic (Lee and Wen ; Navarro and Zhao ; Sprecher et al. ).…”