In Situ Hydrophobization of Lithium Aluminate Particles for Flotations by Dry Grinding in the Presence of Punicines

The engineered artificial mineral (EnAM) lithium aluminate (LiAlO₂) is a promising candidate for the recycling of lithium from slags, which can originate from the reprocessing of batteries, for example. Derivatives of the natural product Punicine (1-(2′,5′-dihydroxyphenyl)-pyridinium) from Punica granatum have been proven to be effective switchable collectors for the flotation of this mineral as they react to light. In the present study, three Punicines were added to a planetary ball mill before grinding LiAlO₂ to particle sizes suitable for flotation. We investigated the influence of Punicine and two derivatives with C10 and C17 side chains on the grinding results at different grinding times and conditions as well as on the yields in flotations. SEM images of the particles, IR and ICP–OES measurements provided insights into the Punicine–particle interactions. They showed that Punicines not only prevent the formation of hydrophilic and thus undesirable lithium aluminate hydroxide hydrate (LiAl₂(OH)₇ ▪ x H₂O) surfaces in this process, as is unavoidable in aqueous flotation without this pretreatment, they also prevent the undesired release of lithium cations into the aqueous phase. Due to considerable hydrophobization of the particle surface of LiAlO₂, nearly quantitative recovery rates of this engineered artificial mineral are achieved using the process described here.