Flotation of the mineral lithium aluminate by application of the natural product punicine and some derivatives as collectors is examined. Punicines, 1‐(2´,5´‐dihydroxyphenyl)‐pyridinium compounds, are switchable molecules whose properties can be changed reversibly. They exist as cations, neutral mesomeric betaines, anions, and dianions depending on the pH. In light, they form radicals. Five punicine derivatives were prepared which possess β‐methyl, β‐chlorine, γ‐tert.‐butyl, and γ‐acetyl groups attached to the pyridinium ring, and a pyrogallol derivative. LiAlO2 reacts with water to give species such as LiAl2(OH)7 on its surface. Flotations were performed applying the punicines in daylight, in darkness and under UV‐irradiation (390 – 400 nm). The pH of the suspension, the collector´s concentration, the conditioning time as well as the flotation time were varied. The recovery rates strongly depend on these parameters. For example, the recovery rate of lithium aluminate was increased by 116% on changing the lighting condition from daylight to darkness, when the pyrogallol derivative of punicine was applied. UV, FTIR, TGA and zeta potential measurements as well as DFT calculations were performed in order to gain insight into the chemistry of punicines on the surface of LiAlO2 and LiAl2(OH)7 in water which influence the flotation´s results.

中文翻译：

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用于铝酸锂浮选的光开关捕收器，以回收关键原料锂

研究了利用天然产物石榴碱和一些衍生物作为捕收剂对矿物铝酸锂进行浮选。 Punicines，1-(2´,5´-二羟基苯基)-吡啶鎓化合物，是可切换分子，其性质可以可逆地改变。它们以阳离子、中性介观甜菜碱、阴离子和二价阴离子的形式存在，具体取决于 pH 值。在光下，它们形成自由基。制备了五种在吡啶鎓环上连接有β-甲基、β-氯、γ-叔丁基和γ-乙酰基的石榴碱衍生物，以及连苯三酚衍生物。 LiAlO2 与水反应，在其表面生成 LiAl2(OH)7 等物质。在日光、黑暗和紫外线照射（390 – 400 nm）下使用石榴碱进行浮选。悬浮液的pH值、捕收剂浓度、调节时间以及浮选时间各不相同。回收率很大程度上取决于这些参数。例如，当使用石榴碱的连苯三酚衍生物时，将照明条件从白天变为黑暗，铝酸锂的回收率提高了116%。进行 UV、FTIR、TGA 和 zeta 电位测量以及 DFT 计算，以便深入了解水中 LiAlO2 和 LiAl2(OH)7 表面的石榴碱化学性质，这些化学性质会影响浮选结果。