多组分氯盐体系镁锂分离规律初探

以Na2CO3为沉淀剂,初步研究了多组分氯盐混合体系(0.6molMgCl2+1.1molLiCl+3.2molNaCl)中选择性沉镁的工艺规律。结果表明:在25~80℃,总C与总Mg物质的量比n(CT)/n(MgT)]为0.8~1.1时,25℃形成针状MgCO3·3H2O,40℃以上形成Mg5(CO3)4(OH)2·4H2O不规则片状团聚微球,其中40~50℃形成的片状物较为分散且粒径较小,导致固液分离困难。40℃时沉镁率最低。温度越高,Li2CO3越易形成,沉锂率越大。n(CT)/n(MgT)越大沉镁率和沉锂率越高。室温(25℃)、n(CT)/n(MgT)=1.0时,沉镁率达98%以上,且沉锂率<0.1%,镁锂分离效果最好。

Preliminary study on separation of magnesium and lithium in multicomponent chloride salt system

The process of selective precipitation of Mg²⁺ from multicomponent chloride salt mixed system（0.6 mol MgCl₂+1.1 mol LiCl+3.2 mol NaCl） was preliminarily studied with Na₂CO₃ as precipitate agent.The results indicated that at 25~80 ℃ and the amount-of-substance ratio of total C and total Mgn（C_T）/n（Mg_T）] was 0.8~1.1,the MgCO₃·3H₂O needle-like particles formed at 25 ℃ and the irregular spherical agglomerates composed of sheet-like Mg₅（CO₃）₄（OH）₂·4H₂O were obtained above 40 ℃.The precipitates formed at 40~50 ℃ were comparatively difficult to be separated by filtration due to the relative dispersion and the small particle sizes.The precipitation ratio of Mg²⁺ was the lowest at 40 ℃.The higher the temperature,the easier the formation of Li₂CO₃ and the higher the ratio of Li⁺ precipitation.The increase of n（C_T）/n（Mg_T） promoted both the precipitation of Mg ²⁺ and Li⁺.At room temperature（25 ℃） and n（C_T）/n（Mg_T）=1.0,the precipitation ratio of Mg ²⁺ was above 98% and the precipitation ratio of Li⁺ was less than 0.1%,the separation effect of Mg²⁺ and Li⁺ was the best.