Thermodynamic modelling of spodumene decrepitation

Recently, the demand for lithium metal and its associated compounds has been growing exponentially, mainly due to the increased consumption of lithium ion batteries. Consequently, to meet this demand, minerals such as spodumene have become the most important lithium-bearing resources. Although numerous methods have been studied for the extraction of lithium from spodumene, the conventional process of spodumene decrepitation followed by leaching in sulfuric acid, remains the proven commercial process. In the high temperature decrepitation process, α-spodumene is converted into β-spodumene and also some intermediate γ-spodumene can form. In the current research, a comprehensive thermodynamic analysis of the decrepitation of spodumene has been performed using HSC Chemistry® 7.1. Firstly, the thermodynamic data available in the literature for the various relevant lithium aluminosilicates was evaluated and then this data was incorporated into the HSC data base. Secondly, using the experimental data available in the literature, the non-ideal behaviour of spodumene was accounted for by the incorporation of activity coefficients. Finally, the model was applied to the decrepitation of both pure spodumene and also a spodumene concentrate. The modelled conversion results were in good agreement with the process data available in the literature.