Life Cycle Assessment of Representative Individual Light Rare Earth Chloride Production from Bastnaesite in China

Rare earth elements (REEs) have been applied in various economic fields e.g., metallurgy, automotive, electronics, aerospace and agriculture. China is the largest producer and exporter of rare earth in the world. Bastnaesite is an important category of light rare earth minerals. Light rare earth chlorides typically consist of lanthanum chloride, cerium chloride, praseodymium chloride and neodymium chloride. As the public concern on the issues of emission reduction and energy saving during the past decades, it is valuable to evaluate and analyze the comprehensive environmental impact caused by the rare earth industry. A standard LCA study on light rare earth chlorides was conducted in this paper. Allocation was carried out based on the actual situation of the technology currently employed in rare earth industry in China, and the function unit was defined as 1 kg of individual light rare earth chloride. The major part of the life cycle inventory (LCI) was compiled via an investigation on a rare earth enterprise in Sichuan province, located in southwest China, and the absent information were obtained through interviews with experts and published literature. The results indicated that the environmental impact of praseodymium chloride production was much severer than those of the production of lanthanum chloride, cerium chloride and neodymium chloride. The dominant environmental impact categories were fossil depletion potential (FDP), particulate matter formation potential (PMFP) and global warming potential (GWP). The environmental impacts were mainly caused by energy use. PMFP was mostly generated from the indirect production processes. Ammonia, sodium silicate and hydrochloric acid were the cardinal contributors to the aspect of materials consumption.