Direct Methods for Lithium Extraction from Lepidolite and Spodumene Minerals

The Challenge

Conventional processing technologies currently in use for lithium extraction from spodumene (LiAlSi2O6) and lepidolite (K(Li,Al)3(Al,Si)4O10(F,OH)2) are based on the sulphuric acid process. These technologies involve energy-intensive steps such as decrepitation (1100 °C) and sulphuric acid baking (250 °C) in spodumene processing and roasting (750-1000 °C) for lepidolite processing. In this project, lithium extraction from lepidolite using direct acid leaching at temperatures less than 100°C was investigated.

Key Findings

The use of lepidolite additives during leaching was investigated and proved beneficial in the direct acid leaching of β-spodumene as lepidolite additions of 5%, 10% and 15% (w/w) increased the Li extraction to 47%, 77% and 80% respectively in phosphoric acid.

The use of lepidolite additives improved Li extraction from α- spodumene vastly in a sulphuric acid leach. Li extraction from α-spodumene leaching in H2SO4 increased from a very low 2.5 % to 58%, 67% and 84% with lepidolite additions of 5%, 10% and 15% (w/w) respectively.

The direct extraction of Li through the elimination of one or more calcination/roasting steps reduces the energy intensity of the process and translates to lower capital costs.

Benefits to WA

Angeline is investigating the preparation of battery-grade lithium salts from different types of Western Australian mineral resource. Her work will help define new processing techniques, supporting WA refineries in designing processes to produce materials ready for the demanding electric vehicle battery market. Developments based on Angeline’s research could be important in consolidating WA’s position as a key global lithium player in meeting global demand for these important materials in the coming decades.

Supervisors

Associate Professor Gamini Senanayake and Dr Manickam Minakshi Sundaram