Date of Award

Spring 2016

Degree Type


Degree Name

MS Metallurgy

Committee Chair

Jerome Downey

First Advisor

Rodney James

Second Advisor

Larry Twidwell

Third Advisor

William Gleason

Fourth Advisor

Hsin-Hsiung Huang


Rare earth elements are part of the lanthanide series in the periodic table. The uses and applications for these elements are ever increasing. Applications vary from smart phones to medical imaging equipment and more.

Current separation techniques used today are hydrometallurgically intensive. The purpose of this study was to investigate a pyrometallurgical alternative to separate rare earth elements in ores. The proposed method, chlorination, would convert the rare earth oxides to chlorides and then apply vapor phase separation techniques to isolate the rare earth chlorides by temperature.

Various reagent grade rare earth oxides were initially studied to determine chlorination efficiencies. Chlorination optimization experiments were then performed on Yb2O3, where the parameters were refined. Experimental products were analyzed by x-ray diffraction and inductively coupled mass spectrometry to determine overall conversion efficiency. The optimized parameters of 330oC, a molar ratio (NH4Cl:REO) of 21:1, and a time at temperature of one hour were applied to actual rare earth ore and concentrate samples. Overall conversion efficiencies of 92.15% were achieved from concentrate samples and 94.51% from ore samples.

A sequential method was applied to high temperature vaporization experimentation. First, thermogravimetric analysis and individual vaporization experiments were performed on reagent grade rare earth chlorides. Next, trials proceeded to separate mixed series of light and heavy reagent grade rare earth chlorides. Lastly, vaporization techniques were applied to chlorinated ore samples. Results were determined through SEM evaluation on the captured residues. Although selective vaporization was observed, further evaluation is necessary to understand and refine the process.

Included in

Metallurgy Commons