高岭土在盐湖卤水提锂中的应用

Extraction of lithium from salt lake brine with kaolinite

煅烧酸浸法对高岭土进行处理,得酸改高岭土和铝浸出液。以酸改高岭土对当雄错盐湖卤水中的锂进行吸附,铝浸出液沉淀吸附后卤水中剩余的锂,再以铝浸出液作吸附后酸改高岭土的解吸剂,并对解吸液再次进行沉淀提锂,从而确定高岭土在盐湖卤水提锂中的最佳工艺。结果表明:高岭土煅烧酸浸后Al_2O_3溶出率高,浸出液中的AlCl_3浓度可达0.97mol/L,而所得酸改高岭土孔洞丰富,比表面积较大;以酸改高岭土对锂浓度为320mg/L的卤水进行吸附,发现在酸改高岭土用量为4.0g、体系pH为12、吸附温度为40℃、吸附时间为150min时,有最大锂吸附量,为4.51mg/g;此时,吸附后卤水中锂的浓度为230mg/L,再以铝浸出液沉淀该卤水中的锂,当Al/Li摩尔比为3.5、Na/Al摩尔比为2.7、反应温度为55℃、反应时间为1h时,锂的最大沉淀率为45.3%;将铝浸出液用水稀释1倍,取35m L对4.0g吸附后的酸改高岭土进行解吸,55℃反应20min,Li+解吸率达93.12%,Li+浓度为480mg/L,再次沉淀提锂时,锂沉淀率为84.51%。

This work applied calcination and acid leaching method to treate kaolinite, and obtained acid modified kaolinite with aluminum leaching solution. Then used acid modified kaolinite to adsorb lithium from Dangxiong Tso Salt Lake brine. To treat the remaining lithium in the brine after the adsorption, the aluminum leaching solution was used as the desorbent to desorb acid modified kaolinite, and again precipitated lithium from the desorption solution. The optimal process parameters of lithium extraction from salt lake brine with kaolinite were determined by this way. Results show that the mass concentration of lithium in the brine after adsorption was 230 mg/L, and then the lithium was precipitated by the aluminum leaching solution. The maximum lithium precipitation rate was achieved at 45.3% when mole ratio orAl to Li was 3.5 and Na to A1 was 2.7, reaction temperature was 55℃ and reaction time was lh. The desorption process used 35 mL of the aluminum leaching solution which was diluted 1 time by water to desorb 4g acid modified kaolinite after adsorption. Desorption rate of Li＋ was 93.12% under 55℃ for 20min, and the mass concentration of Li＋ was 480mg/L. Lithium precipitation rate was 84.51% after precipitation again.