High purity titanium refining by iodide purification

An improved method using the iodide process has been developed to purify titanium metal to high purity. The purification method consists of(1) in-situ generation of titanium tetraiodide from crude titanium, (2) purification of titanium tetraiodide by distillation, and (3) decomposition of purified titanium tetraiodide to high purity titanium metal. Titanium tetraiodide with 99.9976% purity was generated from crude Ti sponge with 99.5% purity. The titanium tetraiodide was subsequently distilled to 99.999% purity. Purity level of titanium metal was ultimately increased from 99.5% to 99.998%. Purification effects of the three processes are discussed. Thermodynamics of the iodide process, titanium tetraiodide, and impurity iodides are discussed. A computerized control and data acquisition system was employed to control reactor temperatures, reactor pressures, and electric power inputs for heating up deposition surfaces. Experimental data and purity levels are compared with those reported by other researchers.