Recovery of Rare Earth Elements from Bauxite Residue: A Comparative Economic Analysis

Abstract

Rare earth (RE) elements, are important in many applications such as lighting
phosphors, lasers, rechargeable batteries, motors in automobiles, wind turbines, appliances,
computers, and hard drives. Despite their common name, REs are not particularly rare, as their
concentration in the earth's (150-220 parts per million (ppm)) is comparable to other elements
such as zinc (70 ppm) which are not considered to be rare at all. Importantly, REs occur together
in ores and since the chemical and physical properties are same, separation is very challenging.
During the past 15 years, China has provided the vast majority of the world’s RE supply. This
essential monopoly of Chinese RE producers became problematic in 2010 when export quota
limited the availability of the RE elements. The resulting price spikes for REs exposed the nonsustainable nature of the RE supply chain lead to several approaches to limit price and
availability fluctuations of these important elements, including stockpiling, replacement of REs in
applications, recovery of REs from end-of-life materials. In view of this there’s a growing interest
in recovering and recycling REs from secondary resources. Bauxite residue or “Red mud” is a
potential source for rare earth elements. The highly alkaline waste is stored in holding ponds and
is produced at a rate of 120 million tons/year and 2.7 billion tons is already stockpiled. The
composition of REEs in the red mud varies with its place of origin. Owing to its large volume and
environmental impact, there’s a need for an effective method for the remediation of red mud. But
the number of reports available on the recovery of REEs from red mud is limited. Herein, an
attempt has been made to compare the economics of the various reported processes using ASPEN
PLUS and ASPEN Process Economic Analyzer.