Abstract
The conventional processing of β-spodumene involves decrepitation at about 1100 °C, digestion with concentrated sulfuric acid at 250 °C, and several purification stages that identify the process with high energy, feedstock, and by-product intensity. In addition to the low-value by-product of sodium sulfate (Na2SO4), the disposal cost of another by-product, hydrogen aluminosilicate (HAlSi2O6, aka keatite-HAlSi2O6), drives the research to avoid its formation in lithium refineries or converting this material into marketable products such as zeolites. Two processes are developed to leach lithium from β-spodumene in a single digestion step using solutions of NaCl, with and without the addition of NaOH, operating at up to 200 °C. The optimised processes extract at least 92.9% of Li by varying the leaching time, temperature, liquid to solid mass ratio, NaCl/β-spodumene mass ratio, solution pH and agitation. The two processes are simple, prevent using concentrated sulfuric acid and preclude forming HAlSi2O6 and Na2SO4 by-products, resulting in significantly lower amounts of impurities in the leach liquor, and high selectivity for lithium extraction. The keatite process functions at circumneutral pH, high NaCl/β-spodumene and L/S ratios and generates sodium aluminosilicate (keatite-NaAlSi2O6) as a by-product. The analcime process requires alkaline pH to produce analcime (NaAlSi2O6·H2O) as a by-product. The study demonstrates a shift in the mechanism between circumneutral and alkaline conditions from ion exchange to dissolution-precipitation (i.e., recrystallisation). In an analogy to keatite and analcime processes for NaCl, we also investigate the extraction of lithium from β-spodumene with KCl with and without KOH but find both reactions to be ineffective in recovering Li. The analcime process offers a cleaner and less hazardous alternative to the conventional sulfuric acid process while maintaining a high lithium extraction effectiveness, rapid reaction rates and high concentration of Li in the leach.
| Original language | English |
|---|---|
| Article number | 105985 |
| Pages (from-to) | 1-13 |
| Number of pages | 13 |
| Journal | Hydrometallurgy |
| Volume | 215 |
| DOIs | |
| Publication status | Published - Jan 2023 |
Bibliographical note
Funding Information:The authors would like to thank Tianqi Lithium Kwinana Pty Ltd. as our industrial partner for partly funding this project. M.F.A. acknowledges with gratitude Tianqi Lithium Kwinana Pty Ltd. and Murdoch University for jointly funding his PhD scholarship, and Murdoch University for providing a waiver of tuition fees. We are indebted to Talison Lithium Ltd for providing the spodumene concentrates investigated in this work. We thank our colleagues and staff at Charles Darwin and Murdoch Universities for many fruitful discussions. We acknowledge the facilities, and the scientific and technical assistance of Microscopy Australia at the Centre for Microscopy, Characterisation & Analysis at The University of Western Australia. H.C.O. acknowledges financial support through the Murdoch University's R&I Seed Grants 2021.
Funding Information:
The authors would like to thank Tianqi Lithium Kwinana Pty Ltd. as our industrial partner for partly funding this project. M.F.A. acknowledges with gratitude Tianqi Lithium Kwinana Pty Ltd. and Murdoch University for jointly funding his PhD scholarship, and Murdoch University for providing a waiver of tuition fees. We are indebted to Talison Lithium Ltd for providing the spodumene concentrates investigated in this work. We thank our colleagues and staff at Charles Darwin and Murdoch Universities for many fruitful discussions. We acknowledge the facilities, and the scientific and technical assistance of Microscopy Australia at the Centre for Microscopy, Characterisation & Analysis at The University of Western Australia. H.C.O. acknowledges financial support through the Murdoch University's R&I Seed Grants 2021.
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