Zirconium and hafnium separation without waste generation.
The history of commercial processes for zirconium/hafnium production and separation is reviewed. A new technology is then proposed as a potential alternative for zirconium/hafnium separation in a simpler, cleaner way than achieved with current processes. Primary sources of zirconium always contain small amounts of hafnium that must be removed during production of zirconium metal for nuclear applications. This separation is usually carried out by a solvent extraction process, developed in the 1950s, that selectively extracts hafnium, as a thiocyanate complex, using methyl isobutyl ketone (MIBK). Environmental problems inherent to this process are the high aqueous solubility and low flash point of MIBK, and possible gaseous contaminants formation generated by the decomposition of the thiocyanic complexes in hydrochloric acid medium (H2S, HCN, mercaptanÕs formation). The present work shows how these problems could be avoided by using organophosphorous extractants that were unavailable when the MIBK process was developed.
Environment, Zirconium, Hafnium, Separation technology.