An Overview Of Hafnium Applications
Hafnium belongs with Ti and Zr to Group 4 of the periodic table. It has an atomic number of 72 and an atomic mass of 178. The geochemical properties of hafnium and zirconium are largely comparable. The ionic radius of hafnium measures 71 pm, whereas that of zirconium is 72 pm. All zirconium minerals contain hafnium, and pure hafnium minerals have not been reported.
Magmatic and metamorphic rocks typically contain low concentrations of hafnium. Hafnium can be used as an indicator for zirconium mineralisation. Elevated hafnium values denote the presence of felsic rocks, particularly intrusive bodies. The resistant nature of hafnium-bearing minerals restricts the concentration of hafnium in natural water. Hafnium is present in natural waters at concentrations below 0.1 µg l-1.
Wastewater constitutes the primary anthropogenic source of hafnium. Hafnium is utilised in the manufacture of light bulb filaments, X-ray cathode tubes and reactor control rods. It is also employed in the production of alloys with Ti, Nb, Ta and Fe, and in the ceramics industry. Several studies conducted during the 1960s and 1970s have indicated that hafnium concentrations in areas with industrial activity are not elevated. Geological sources of hafnium appear to be more significant than anthropogenic ones. Hafnium does not have any known biological function. Available data on the toxicity of hafnium are limited; however, it is generally regarded as minimally toxic. No adverse environmental effects have been reported. Given the limited information on the effects of hafnium on human health, it should be treated as potentially toxic.
Hafnium