Purification of terbium by means of argon and hydrogen plasma arc melting

•The final purity of terbium can reach to 99.9521%.•The temperature distribution and the gas flow can be simulated.•Hydrogen H I spectra dissociate from H2 can be detected.•Impurities emitted by atoms, oxide and hydride molecules can be detected.•Activated hydrogen atoms bringing special physical and chemical interactions.

The refining of terbium (Tb) by plasma arc melting using pure Ar and Ar + H2 mixture was examined, respectively. The temperature distribution and gas flow of the plasma arc during the melting process were simulated. The residual metallic impurities were examined by inductively coupled plasma-atomic emission spectrometer. Experimental results show that both methods of argon plasma arc melting (APAM) and hydrogen-argon plasma arc melting (HAPAM) can lead to a good removal of metallic impurities despite of high initial concentrations. HAPAM displays a better refining effect of Tb metal. Activated hydrogen atoms dissociated in high temperature plasma arc, bringing on special chemical interactions, are supposed to be the cause for the wonderful refining effect. The detailed behaviors of impurities and hydrogen atoms are discussed systematically in this study.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide