Indian Coal Ash: A Potential Alternative Resource for Rare Earth Metals (REMs)

Huge scarcity of rare earth metals (REMs) globally, lack of good natural resources, and generation of tremendous coal ash containing REMs of power plant attracted the researchers to work in this area. The analysis of geologically distributed heterogeneous coal samples at CSIR-NML, India reports the presence of 0.5–1.5 kg/Ton REMs in particular seam of coal at Indian eastern part. In this regard, systematic leaching studies were made to recover REMs from Indian coal ash using hydrometallurgical technique. Maximum dissolution of REMs from coal ash take place using HCl of concentration ranging between 2 and 6 M at elevated temperature. From the obtained leach liquor, more than 90% REMs were recovered using oxalate precipitation. The process developed has tremendous potential to be commercialized after feasibility studies.