Critical Minerals:Their Nature, Occurrence, Recovery and Uses

Critical minerals (CMs) are metals and non-metals which are vital for the economic well-being of society. However, their supply may be at risk due to geological scarcity, geopolitics, trade policy, vulnerability and other factors. CMs include REEs, PGEs, Li, Be, Ga, Ge, In, W, Co, Nb–Ta, Mo, Sb, V, Ni, Te, Cr, Sn, Th-U, Zr, Hf, Se, Te, Re, phosphate, potash, etc. They occur in three sources, viz. primary – in ore deposits; secondary – in waste, like the electronic (e)-waste, and tertiary – in imports. Currently, many CMs (like REEs, PGMs, Cr, W, Co, Cd, Ge, Se, Te and Re) are recovered primarily during the mineral processing of ores of major commodities, such as Cu, Pb, Zn, Ni and Au. Some CMs like Au, Ag, Pt, Co, Sn and Al are being recovered and reused by recycling the environmentally hazardous, but valuable e-waste that contains ~50 chemical elements. The CMs thus recovered are in much demand in diverse industries based on conventional, high-tech and cuttingedge technologies.