Montana Tech Library Digital Commons @ Montana Tech Graduate Theses & Non-Theses Student Scholarship Spring 2016 CHLORINATION AND SELECTIVE VAPORIZATION OF RARE EARTH ELEMENTS Daniel Gaede Montana Tech of the University of Montana Follow this and additional works at: http://digitalcommons.mtech.edu/grad_rsch Part of the Metallurgy Commons Recommended Citation Gaede, Daniel, "CHLORINATION AND SELECTIVE VAPORIZATION OF RARE EARTH ELEMENTS" (2016). Graduate Theses & Non-Theses. 72. http://digitalcommons.mtech.edu/grad_rsch/72 This Thesis is brought to you for free and open access by the Student Scholarship at Digital Commons @ Montana Tech. It has been accepted for inclusion in Graduate Theses & Non-Theses by an authorized administrator of Digital Commons @ Montana Tech. For more information, please contact [email protected]. CHLORINATION AND SELECTIVE VAPORIZATION OF RARE EARTH ELEMENTS by Daniel W. Gaede A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Metallurgical and Materials Engineering Montana Tech 2016 i Abstract 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 o optimized parameters of 330 C, 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. Keywords Rare Earths, Halogenation, Chlorination, Volatization, Vapor Phase Extraction, Thermodynamics ii Dedication First, I would like to dedicate this to my family, for without their support through the highs and lows, this would not have been possible. Words are not enough. Next, my friends, for their reality checks, humor, and support. Lastly, I wish to acknowledge my overall experience here in Montana. It has been a blast, and I would like to think I have been able to experience more than most who just come out for school. The friendships and experiences are memorable to say the least. From outlandish camping and hunting trips up in the mountains, swimming, floating, and fishing the rivers, incredible snowboarding, breathtaking views, a couple of summers being able to work for the Forest Service (KNF D-4 FIRE), and everything in between, it has been great, and all of it has been worth it!! iii Acknowledgments Bryce Ruffier for working alongside me in the lab through all the ups, downs, late nights, and molten accidents, as well as Ryan Foy and Sean Dudley, fellow graduate students. Neil Wahl and Rod James for their patience, inspiring, and insightful conversations. Dr. Huang and his help with StabCal, allowing me to dig in and begin to understand the rare earth chloride system. Larry Twidwell for his expertise and support in Design Expert. Jerry Downey and Jan Chorney for giving me a chance. Their help, guidance, and knowledge throughout this entire process is greatly appreciated. Gary Wyss from CAMP for his help with MLA and XRD analysis. Hazen Research for performing analysis on leach solutions and/or residues for rare earth content. Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-15-2-0020. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. iv Table of Contents Abstract .............................................................................................................................................. i Keywords ............................................................................................................................................ i Dedication...........................................................................................................................................ii Acknowledgments ............................................................................................................................... iii List of Figures ..................................................................................................................................... xii List of Tables ................................................................................................................................... xxxi List of Equations ............................................................................................................................ xxxiv Glossary of Terms ........................................................................................................................... xxxv 1. Introduction..................................................................................................................................................... 1 1.1. Mineralogy ............................................................................................................................................. 5 1.2. Extractive Processes ............................................................................................................................ 11 1.3. Environmental ..................................................................................................................................... 14 2. Literature Review .......................................................................................................................................... 15 2.1. Carbochlorination/Chlorination ........................................................................................................... 15 2.2. Chlorination/Volatization .................................................................................................................... 25 2.3. Volatization .......................................................................................................................................... 26 2.4. TGA Analysis......................................................................................................................................... 31 3. Theory ........................................................................................................................................................... 35 3.1. Chlorination ......................................................................................................................................... 35 v 3.1.1. Gibbs Free Energy ......................................................................................................................... 36 3.1.2. Gibbs Free Energy and Equilibrium ............................................................................................... 39 3.1.3. Low Temperature Predominance Area Diagrams ......................................................................... 40 3.2. Vaporization ......................................................................................................................................... 43 3.2.1. Reagent Grade, Lights and Heavy Separation ............................................................................... 43 3.2.2. High Temperature Predominance Area Diagrams ........................................................................ 51 4. Experimental ................................................................................................................................................. 56 4.1. Chlorination ......................................................................................................................................... 56 4.1.1. Chlorination with Ammonium Chloride ........................................................................................ 56 4.1.1.1. Experimental Matrix with NH4Cl(s) ......................................................................................... 57 4.1.1.2. Experimental Matrix with HCl gas .........................................................................................