Paper Title
Bio-Solvo-Chemical Extraction of Rare Earth Metal from Spent Catalytic Converter

Extraction of rare earth metal, cerium from the spent catalytic converter has been studied using an integrated bio-solvo-chemical technique. Precious metals were firstly leached in biogenic lixiviant followed by the mineral acid leaching of cerium, wherein, HF added acid mixture showed leaching efficiency up to 96% of cerium. The determined value of activation energy, 31.8 kJ/mol revealed that leaching progressed via diffusion-controlled mechanism. Subsequently, cerium from leach liquor was extracted using 4 tri-alkyl phosphine oxides in kerosene, which indicated the formation of extracted species to be〖[〖〖Ce(SO〗_4)〗_2.2L.HSO_4^-]〗_org. The loaded organic was quantitatively stripped back into the H2SO4 solution by adding an H2O2 dosage as a reducing agent. Thus obtained Ce-bearing stripped solution was treated with oxalic acid to precipitate high-purity Ce2(C2O4)3. The process is simple and potentially dealt to recycle the critical metal values which remained less attractive until now. Keywords - Bio-solvo-chemical Extraction; Integrated Process Metallurgy; Rare Earth Metals, Spent Automobile Catalysts