Analogy and differences between aluminium and titanium electrowinning

Abstract

Titanium is the ninth most abundant element and the forth most common construction metal in the earth’s crust. It’s high strength, high-temperature performance, low density, high corrosion resistance and bio-compatibility makes it the ideal materials choice in a wide variety of applications. However, the global production and use of titanium are very small due to its high cost of production. Since 1946 when the titanium industry began to evolve following the commercialisation of the Kroll process, many attempts had been undertaken to reduce the cost of producing titanium. To date all the attempts failed commercially and only the Kroll and to a lesser extent the earlier Hunter processes are used commercially. One of the numerous process alternatives considered is electrowinning of molten titanium in an analogous way to aluminium electrowinning. This process is conceptually very attractive and if successful could provide the cost breakthrough required to make titanium affordable to a much larger market. The authors have tested this route experimentally, but could not produce pure titanium. The failure of electrowinning pure, molten titanium has been interpreted in terms of the analogy and differences between aluminium and titanium electrolysis resulting in a clear understanding of the fundamental obstacles that have to be overcome in order to develop such a process successfully.