Rare Earth Elements: Overview, General Concepts, and Recovery Techniques, Including Electrodialytic Extraction

Rare earth elements (REEs) are critical raw materials, crucial for many technologies and used in a variety of industries. Their potential supply risk holds serious consequences for the industry and value chain. With limited substitutability for a range of applications and low recycling rates from end products, finding alternative secondary sources and efficient processes for selective REE recovery are crucial. This chapter presents the state of the art of REE properties, the European and US contexts, alternative secondary sources, and extraction techniques. Particular emphasis is given to coal ashes, as they are substantial sources of REEs. An examination is also carried out on a case study where anthracite ash from Pennsylvania (US) is reported as an effective source of critical REEs and electro‐based technologies have the potential to promote their recovery.