Thermal Treatment of Spodumene (Lialsi2o6) for Lithium Extraction

Thermal Treatment of Spodumene (LiAlSi2O6) for Lithium Extraction Arif A. ABDULLAH, BSc, MSC This thesis is presented for the degree of Doctor of Philosophy Chemical Engineering College of Science, Health, Engineering and Education Murdoch University, Western Australia 2019 i Declaration I declare that this thesis is my own account of my research and contains as its main content work which has not previously been submitted for a degree at any tertiary education institution. Arif A. ABDULLAH December, 2018 ii Dedications To my wife, Without her, none of my success would be possible. iii Acknowledgments The research work presented in this thesis reflects the help and support of many kind people around me, only to some of whom it is possible to give noteworthy salutations here. I would like to thank my supervisors Professor Bogdan Z Dlugogorski, Associated Professor Gamini Senanayake, Dr Hans Oskierski and Dr Mohammednoor Altarawneh for their unwavering and exceptional support. Their understanding, mentorship, encouragement, dedication and magnanimity have provided a good fundamental driving force for the present study. Thank you again; your quick correspondence, corrections and gestures achieved the intended. I am grateful to Iraqi Government’s Ministry of Higher Education and Scientific Research for the award of a postgraduate scholarship. Special thanks to Murdoch University’s Mr Kris Parker, Mr Andrew Foreman, Mr Kenneth Seymour, Mr Stewart Kelly, Dr Marc Hampton, Dr Juita, Ms Jacqueline Briggs and Ms Caitlin Sweeney for their professional and technical assistance. I wish to thank Bjorn Dybdahl, Talison Lithium Pty. Ltd, for providing spodumene concentrates and valuable insights into the operation of the processing plant at Greenbushes, WA. I express my gratitude to Australian Institute of Nuclear Science and Engineering (AINSE) for research grant which enabled HT-XRD the measurements at Australian Nuclear Science and Technology Organisation (ANSTO), as well as Professor Gordon Thorogood and Dr Robert Aughterson for their assistance during the HT-XRD measurements. Synchrotron iv experiments were carried out on the powder diffraction beam line at the Australian Synchrotron, with the assistance of Drs Helen Brand and Fang Xia. I acknowledge my gratitude to my fellow student colleagues and staffs of the Fire Safety and Combustion Kinetics Research Laboratory: Dr Ibukun Oluwoye, Dr Zhe Zeng, Dr Anam Saeed, Dr Niveen Assaf, Dr Ehsan Mohammadpour, Nassim Zeinali, Dr Kamal Siddique, Jomana Al-Nu’airat, Sidra Jabeen, Sana Zahid, Alaa Kamaluldeem, Elie Kabende, James Mulwanda, Mahmoud Alhadad, Kudzai Mchibwa and Thamsanqa Ncube. Courtesy of you all, I experienced exciting and fun-filled years of research and experiments. v Abstract This work provides a detailed description of the qualitative and quantitative mineralogical, dynamic, as well as kinetic aspects for the structural transformation of α-spodumene (α- LiAlSi2O6), and advances the industrial processing of spodumene by introducing two novel alternative technologies that are relatively straightforward and potentially cost-effective. Spodumene, the most abundant lithium-containing mineral, usually undergoes calcination at an extreme temperature of about 1100 ºC and strong-acid digestion during industrial processing. The calcination process stimulates the structural transformation of spodumene from its naturally occurring pyroxene-framework α-phase into the relatively more reactive β- spodumene of the keatite (SiO2) structure. On the other hand, the acid digestion approach facilitates the production of water-soluble lithium compounds (mainly lithium sulfate Li2SO4). This study resolves the technical obstacles associated with cheaper (and safer) processing of spodumene concentrates. The project incorporated intensive experiments to analyse the thermally-activated changes during the calcination of spodumene. The combination of hot-stage and high-temperature synchrotron X-ray diffractometry (XRD) enabled in-situ mineralogical analysis of the transformation processes, identifying (and quantifying) the resulting phases at various temperatures. Each of the diffractometry techniques complements the heating rate and temperature limitations of each other. Likewise, accurate calorimetric and thermogravimetric analyses yielded the corresponding thermodynamic and kinetic functions, allowing the precise determination of the minimum energy required for the heat treatment process. Distinctly, the project also involved detailed investigation on roasting of spodumene with the most effective vi additives, CaO and Na2SO4, for better extraction of lithium. The addition of these chemicals resulted in the formation of water-soluble lithium compounds via the roasting process at a relatively low temperature (800 – 900 ºC). Set of experiments determined the best condition for minimising these additives and maximising the productivity of lithium. Atomic absorption spectrometry (AAS) quantitated the recovered lithium from the roasted spodumene concentrate. Techniques, such as X-ray fluorescence (XRF) and AAS, attested the chemical analyses of the raw spodumene concentrate. The Match! Software allowed phase identification, while HSC 7.1 software facilitated the estimation of energies. The results of this thesis have demonstrated that the transition reaction of spodumene occurs via different pathways, depending on the amorphicity and the thermal history of the mineral. The results have also identified the intermediate species and clarified their appearance as a function of temperature and heating rate, and particle size, relative to the final phase of β- spodumene. For instance, the formation of the recently reported γ-spodumene is initiated by crystallisation of minuscule amorphous materials in the concentrated sample at slow heating conditions, while fast initial heating to 800 ºC prompts the emergence of a newly-identified phase of β-quartzss, at low temperatures of less than 900 ºC. Requiring an operating temperature of above 1000 ºC, the calcination of spodumene concentrate has been elucidated to adopt slow kinetics, with a high activation energy of more than 800 kJ mol-1 and significant dependency on the degree of conversion. The combined outcomes of this study are instrumental in optimising the energy cost of lithium extraction from spodumene mineral in practical operations. In particular, this thesis reveals that, the roasting of spodumene concentrate with a small amount of CaO reduces the transformation temperature by 150 – 200 ºC as determined by in-situ XRD, which translates vii into important energy saving during the calcination of spodumene in the first step of the commercial acid digestion process. Roasting of spodumene with CaO and Na2SO4 at 882 ºC for 2 h results in producing a water-leachable lithium compound of LiNaSO4 with 94 % lithium recovery. Thus, the roasting of spodumene concentrate with these two additives eliminates the aggressive acidic treatment and decreases the operating temperature of the kiln. viii Table of Content Thesis Declaration ii Dedications iii Acknowledgements iv Abstract vi Table of content ix Glossary of Abbreviations and Technical Terms xv 1. Introduction 1 1.1. Introductory Overture 1 1.2. Research Motivation 6 1.3. Research Objectives 9 1.4. Structure of Dissertation 11 1.5. References 13 2. A comprehensive review on processing of spodumene (LiAlSi2O6) for 17 lithium extraction 2.1. Introduction 18 2.2. Lithium Importance, Usage and Demand 21 2.3. Calcination of Spodumene Concentrate 27 2.3.1. Stability of α-spodumene and its high-temperature polymorphs 29 2.3.2. Mineralogical aspects of spodumene transition 33 2.3.3. Calorimetric aspects of spodumene transition 35 2.3.4. Kinetic aspects of spodumene transition 39 2.4. Metallurgical Processing of Spodumene 41 ix 2.4.1. Processing of spodumene via acid digestion route 44 2.4.2. Processing of β-spodumene via alkaline leaching route 46 2.4.2.1. Alkaline leaching via carbonate (soda ash) solution 46 2.4.2.2. Alkaline leaching via hydroxide solution 50 2.4.2.3. Alkaline leaching via chloride solution 52 2.4.2.4. Alkaline leaching with solution of sulfates 53 2.4.3. Processing of spodumene by roasting with additives 56 2.4.3.1. Lime and limestone roasting process 56 2.4.3.2. Roasting processes involving sulfate melts 58 2.4.3.3. Lime-gypsum roasting process 61 2.4.3.4. Chloride/chlorine roasting processes 62 2.5.Potential Advances 64 2.6. References 67 3. Phase transformation mechanism of spodumene during its 77 calcination 3.1. Abstract 78 3.2.Introduction 79 81 3.3. Materials and Methods 81 3.3.1. Chemical analysis 83 3.3.2. Ambient XRD analysis 85 3.3.3. In-situ high-temperature XRD analysis (HT-XRD) 87 3.3.4. In-situ high-temperature synchrotron XRD analysis (SHT-XRD) 88 3.3.5. Processing of XRD measurements 89 3.4. Results and Discussion 89 3.4.1. Phase changes during calcination x 89 3.4.1.1. Transformation of amorphous spodumene 3.4.1.2. Transition of crystalline α-spodumene with a fast initial 93 heating 100 3.4.2. Factors effecting the transition reaction of spodumene 106 3.5. Implications for Processing of Spodumene Concentrate 107 3.6. Conclusions 109 3.7. References 4. Thermodynamics of phase inversion of spodumene: assessment of 114 energy requirements 115 4.1. Abstract 116 4.2. Introduction 120 4.3. Materials and Methods 120 4.3.1. Materials 121 4.3.2. Experimental methods 123 4.4. Results and discussion 123 4.4.1. Characterisation of the transition events during calcination 127 4.4.2. Thermodynamics of spodumene concentrate 4.4.2.1. Variation of heat capacities before the transformation of 127 α-spodumene 131 4.4.2.2. Transformation of spodumene 4.4.2.3. Variation of heat capacities after the transformation of 136 α-spodumene 138 4.4.3. Energy requirements of transformation of spodumene concentrate 141 4.5. Implications to Industrial Processes 141 4.5.1. Energy savings 141 4.5.2. Calcination temperature 142 4.5.3. Capital cost and carbon footprint 143 4.5.4. Integrated process for optimising calcination stage xi 143 4.6. Conclusions 144 4.7. References 5. Kinetics of nonisothermal transformation of α-spodumene (α- 152 LiAlSi2O6) 153 5.1.

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