Purification of Refractory Metals

摘要

Refractory metals belonging to the Group IV-VIB of the periodic table are conventionally produced from their natural sources by a sequence of pyro and hydrometallurgical process first to produce a pure chemical intermediate which is then reduced to crude metal. The physical, chemical and mechanical properties of the metal are very sensitive to the presence of metallic and interstitial impurities. The reduced crude metal is usually subjected to post reduction purification treatment to obtain pure metals. For certain specific applications it is further necessary to purify the metals to still higher purity. This paper briefly reviews the present status on purification of refractory metals such as titanium, zirconium, hafnium, niobium, tantalum, vanadium, molybdenum and tungsten and also presents directions for future research in the field of these metals.