Membrane Solvent Extraction to Recover Rare Earth Elements

Membrane solvent extraction provides an energy-efficient and environmentally friendly process to recover rare earth elements from electronic waste.

Rare earth elements (REEs) — particularly dysprosium (Dy), praseodymium (Pr), and neodymium (Nd) — have recently drawn urgent worldwide attention and have become strategically critical for the security of the global economy. These materials are widely used in clean energy applications such as hybrid/electric cars, wind turbines, and consumer electronics (e.g., computer hard drives). They are also important for many defense applications, such as fin actuators in missile guidance and control systems; disk drive motors installed in aircraft; unmanned aircraft, tanks, and missile systems; satellite communications; and radar and sonar on submarines and surface ships, among others (1).

Due to the high demand but limited supply, Dy and Nd are the most critical elements for clean energy applications with the highest supply risk, according to the criticality matrix of REEs projected for 2015–2025 in the “Critical Materials Strategy” report published by the U.S. Dept. of Energy (DOE) in December 2011 (2). With the ever-increasing worldwide demand, the recycle and reuse of REEs from electronic waste is a promising and sustainable measure for global energy security (3–10).

Recycling and reusing REEs from electronic waste is promising for many reasons. It will help to meet the rapidly growing demand, address the supply risk, mitigate environmentally unsustainable mining practices, and address the concern (environmental regulations and cost) associated with electronic waste management. It is reported that 41.8 million metric tons of e-waste were generated globally in 2014. The U.S. alone generated 7.1 million tons of electronic waste in 2014 (which averages to about 22 kg per person) (11, 12). More than 2,000 tons of REEs are contained in electronic waste. Industry-leading research firm, Adamas Intelligence, estimates that the value of the world’s supply of magnet-oriented rare earth oxides (REOs) will increase from $1.44 billion in 2016 to $6.07 billion by 2025, representing a compound annual growth rate (CAGR) of 17.4% (1).

This article discusses a novel method for recovering REEs from scrap electronic waste that was developed and tested by researchers at Oak Ridge National Laboratory (ORNL)...