LAUSR

Excess lithium in alumina is significantly bad for aluminum reduction. In this study, the concentration variation of lithium ion in sodium aluminate solution with addition of synthetic lithium aluminate was investigated. Elevating temperature, increasing caustic soda concentration, reducing alumina concentration or raising molar ratio α k improved equilibrium concentration of lithium ion in sodium aluminate solution. Agitation speed had a minimal effect on lithium ion concentration. Over 0.65 g/L lithium ion equilibrium concentration was observed in digestion process, whereas 35 mg/L lithium ion concentration remained in solution after precipitation time of 9 h. Moreover, equilibrium concentration decreased sharply from digestion of boehmite or diaspore to seed precipitation, about 95% lithium was precipitated into red mud (bauxite residue) and aluminum hydroxide. This study provides a valuable perspective in removal or extraction of lithium from sodium aluminate solution in alumina refineries.摘要氧化铝中过量的锂不利于铝电解。本文研究了含锂铝酸钠溶液中锂离子平衡浓度的变化。研究 表明,升高温度、增大苛性碱浓度、减小氧化铝浓度或升高苛性比值( α k)将有助于提高铝酸钠溶液 中锂离子的浓度。搅拌速率对锂离子浓度影响很小。在拜耳溶出过程中,当铝酸钠溶液中锂离子平衡 浓度超过0.65 g/L 时,在晶种分解9 h 后,铝酸钠溶液中锂离子浓度仅为35 mg/L。进一步研究发现, 勃姆石或硬水铝石的溶出过程到晶种分解过程锂离子的平衡浓度急剧下降,大约有95%的锂会进入赤 泥和氢氧化铝中。本文为氧化铝厂铝酸钠溶液中高效去除锂或回收锂提供了依据。