Study on phase transformation and lithium extraction of amblygonite using low temperature acid free roasting method

The demand for lithium resources is constantly increasing with the vigorous development of the new energy industry. Extracting lithium from various lithium containing resources through green and environmentally friendly methods has become a research hotspot and has attracted widespread attention. A method for extracting lithium from amblygonite by low-temperature acid free roasting combined with mild leaching is proposed in this paper. The lithium extraction process of amblygonite was studied, and its phase composition and phase transition behavior during calcination were discussed in detail. The thermodynamic analysis by HSC 6.0, series of experimental investigation, and characteristics tests on the roasting product by XRD were carried out. The research results indicate that the transformation of LiAl(PO 4 )(F, OH)→AlPO 4 , LiAlSi 2 O 6 , and LiF in amblygonite can be achieved through acid free roasting process. Under the action of chloride additives, this phase transformation process will be promoted, and the lithium extraction rate will also be improved. After being chlorinated and roasted at 850 °C, amblygonite is leached by HCl with a concentration of 0.6 mol/L, a liquid-solid ratio of 4 mL/g, a temperature of 95 °C, and a reaction time of 1.5 h. The lithium extraction rate can exceed 96%. The external dependence on spodumene mineral resources can be alleviated, which has a positive effect on promoting the green and healthy development of the lithium battery industry.