Éléments08: Science, Strategy, and Partnerships in Support of CSMs

Lithium-bearing pegmatites represent a critical source of lithium for the production of battery raw materials, however complex mineralogical and textural variability of lithium-bearing minerals and gangue across different lithologies in an ore deposit can pose significant challenges for optimal resource exploitation and processing. The aim of this research project was to improve the knowledge of lithium pegmatite ore deposits, with a focus on enhancing the mineralogical understanding of these deposits in Québec, through a geometallurgical approach. Geometallurgy, which combines geological, mineralogical, chemical and metallurgical information to improve orebody knowledge, to optimise resource extraction, and reduce technical risks, is a key multidisciplinary approach to addressing the challenge. The study combined quantitative mineralogical characterization, geochemical analyses, and comminution testing for a range of different lithologies from two case-study deposits to establish relationships between mineral assemblages and texture, lithium-bearing mineral characteristics, and ore hardness, using high-resolution analytical techniques, including automated mineralogy (TIMA), X-ray diffraction (XRD), and chemical analyses. The overall aim of this collaborative research project was to improve the overall mineralogical understanding of these ores within a geometallurgical framework to support exploitation strategies and the sustainable valorisation of Québec’s pegmatite-hosted lithium deposits.

The conventional process for extracting lithium from spodumene concentrate uses sulfuric acid to generate a Li sulfate stock solution. However, this acid leaching is not perfectly selective for lithium, and also causes other species such as Fe, Al, Mn, Si, Mg, Ca, etc. to dissolve. The process includes purification steps to remove these impurities and obtain a high-purity lithium sulfate solution, which is then converted into lithium hydroxide or lithium carbonate crystals.

Little data exists on the solubility of calcium carbonates in conditions as basic and rich in lithium sulfate as those found in conventional process solutions. The objective of this project is to study the solubility behaviour of calcium carbonates and to provide a better understanding of the efficiency of calcium precipitation as a function of reaction parameters such as temperature, presence/absence of dissolved carbonates, the basicity of the medium, and the concentration of Li sulfate. The study is initially conducted with synthetic solutions, then with representative solutions derived from spodumene concentrate. Better control of this operation will help improve and stabilize calcium removal performance, reduce the costs of subsequent ion exchange resin operations, and minimize reagent consumption.

Spodumene is the principal hard-rock source of lithium for battery materials. The conventional extraction method, phase transition from α- to β-spodumene, followed by sulfuric acid roasting and water leaching, achieves high lithium recoveries but presents significant challenges. It requires elevated temperatures and large quantities of reagents, generates acidic residues that are difficult to valorize, and involves complex purification steps. These limitations motivate the search for alternative processes that are both efficient and environmentally sustainable.

Two promising approaches highlighted in recent studies are:

- Binary salt roasting, using sodium sulfate and calcium oxide at lower temperatures, followed by simple water leaching. This method achieves high lithium extraction without acidic or alkaline reagents in the leaching step, reduces impurity dissolution, lowers energy demand, and produces neutral residues with potential use in ceramics or construction.

- Alkali chloride-based high-pressure leaching (analcime method), where α-spodumene is calcined to β-spodumene and treated with mixed chloride-alkali systems in an autoclave. This route provides high lithium recovery with minimal co-dissolution of impurities, while producing stable aluminosilicate tailings, predominantly analcime, a neutral by-product with reuse potential.

Both processes avoid the use of concentrated sulfuric acid and produce cleaner leach solutions with minimal impurity transfer, highlighting their potential for more environmentally responsible lithium refining. However, feasibility and pilot-scale studies are still required to validate their industrial applicability and assess process economics, environmental performance, and scalability. The presentation will provide an overview of these alternative routes and their implications for sustainable lithium production.

With the support of the government departments and the private companies involved, Elements08 is striving to provide scientific and technical data that will be useful to the development vision of its industrial partners who mine lithium in Québec. The centre has set itself three objectives for the recovery of waste as part of this project. The first objective is to assess the potential for separation and concentration of valuable minerals other than lithium-bearing minerals in order to reduce the volume of final residues to be stored and managed in the long term. The second objective is to reduce the levels of residual lithium in the tailings with a view to continuously improving the process. The third is to assess the potential uses and markets for these recovered residues.

After mineralogical characterization of the materials studied, innovative technical solutions to current, specific and prioritized industrial problems are explored on a laboratory or mini-pilot scale. The data transferred to the partners will enable them to plan their future developments and to test these approaches on an industrial scale and improve either their productivity or the quality of their products. In order to respect the agreements, only the general aspects of this project will be presented, focusing on the opportunities and challenges encountered in helping the sustainable development of the energy transition, as well as the establishment of a circular economy and a domestic supply of strategic minerals.