An alternative process of pre-roasting, phosphoric acid leaching followed by solvent extraction of a limonitic laterite ore was described in this work, with emphasis on the solvent extraction of Ni and Co from the phosphoric acid leaching solution by P204 and P507. First, the pH value of the leaching solution was adjusted using ammonia to reduce the content of Al³⁺ and Fe³⁺ by precipitation, then the content of Al³⁺, Fe³⁺ and Mn²⁺ were further decreased by extraction using P204. At last, Ni²⁺ and Co²⁺ were separated by three-stage extraction using P507. After extraction, the extraction ratio of Co²⁺ was 96.61%, while that of Ni²⁺ was 12.32%, and the selective extraction of Ni²⁺ and Co²⁺ could be realized.

The growing demand for lithium, driven by the widespread adoption of electric vehicles and renewable energy storage systems, has sparked interest in developing low-grade lithium resources. This comprehensive review explores the types, distribution, extraction technologies, challenges, and future prospects of low-grade lithium resources. This article focuses on low-grade lithium sources such as clays, brines, coal, and coal by-products, and analyzes the principles, advantages, and limitations of key extraction techniques, including acid-alkaline leaching, bioleaching, adsorption, and membrane separation. Furthermore, this review discusses the technical, economic, and environmental sustainability challenges associated with developing low-grade lithium resources and proposes corresponding strategies. Future research should focus on improving the selectivity and efficiency of extraction and processing technologies, optimizing separation processes, and developing green and cost-effective extraction methods. Establishing supportive policy frameworks, strengthening international cooperation, and knowledge sharing are crucial for promoting the sustainable development of low-grade lithium resources. This review provides stakeholders with comprehensive insights and recommendations for addressing the growing lithium demand and achieving the Sustainable Development Goals.

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na₂CO₃-MgSiO₃-Mg₂SiO₄-Mg₂B₂O₅ via FactSage show that the formation of Na₂MgSiO₄ was preferential for the reaction between Na₂CO₃ and MgSiO₃/Mg₂SiO₄. While, regarding the reaction between Na₂CO₃ and Mg₂B₂O₅, the formation of NaBO₂ was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate.