Abstract
The increasing demand for lithium-ion batteries has led to a surge in the development of new lithium mineral projects across the globe. From a mineral processing perspective, these projects face two major challenges: similar behavior of value and gangue minerals and increasingly complex mineralogies. The primary collectors in commercial spodumene flotation are anionic unsaturated fatty acids, such as tall oil or sodium oleate. While powerful, these collectors are notorious for poor selectivity and strong frothing properties. At the pH range used in spodumene flotation, the concentration of ionic collector species is very sensitive to pulp conditions, and the precise behavior of these species is not well understood; possibly resulting in unstable flotation circuits that are difficult to control. Researchers agree that spodumene flotation using fatty acid collectors relies on the adsorption of acid-anion complexes onto cationic Al3+ surface sites. However, several authors reported poor spodumene recoveries without cationic activators to enhance collector adsorption. Collector development research to improve selective spodumene recovery has focused heavily on the development of mixed anionic/cationic collector systems, which exploit spodumene’s natural negative surface charge under neutral to alkaline conditions– a property of many silicate minerals. This paper reviews research on the use of fatty acids for the flotation of spodumene and other minerals with similar collector adsorption mechanisms, like iron and titanium oxides. Most published studies conducted testing using pure sodium oleate, revealing a significant gap in the research on the impact of impurities in commercial tall oil collectors on froth properties, collector-particle interactions, and ultimately, the selective rejection of gangue minerals. Through this review, we aim to examine the properties of fatty acids and the state of fatty acid collector research in oxide mineral flotation, provide new insight for understanding collector-particle interaction in spodumene flotation, and highlight areas of research that are needed to de-risk projects in the growing lithium mineral industry.