复合沉淀剂用于高镁锂比卤水锂镁分离研究

Separation of lithium and magnesium from high Mg/Li ratio salt lake brine by using compound precipitant

采用复合沉淀剂,用沉淀法从高镁锂比卤水沉淀镁而实现锂镁分离。复合沉淀剂由氢氧化钠与辅助沉淀剂(对硝基偶氮苯酚)构成。对硝基偶氮苯酚是以对硝基苯胺与苯酚为主要原料,经重氮化及偶联反应得到,其产率为87%。合成产物经实测红外光谱吸收频率与高斯计算频率对比,其主要官能团吸收频率吻合度极高,用质谱佐证表明合成产物为目标产物。通过XRD,SEM表征复合沉淀剂得到的沉淀形态,其沉淀的结构和形态发生了大的变化,得到颗粒大而完整的沉淀。采用该复合沉淀剂对模拟卤水进行锂镁分离,其除镁率达到99.999%,锂损失率低于2%,得到的沉淀极易过滤。

At present,the separation of lithium and magnesium in salt lake containing high magnesium-lithium ratio is a key technical problem in the development of salt lake brine. With the aid of the compound precipitant,the separation of lithium and magnesium was achieved by using the precipitation method. The compound precipitant was composed of sodium hydroxide and auxiliary precipitant [4-（（ 4-nitrophenyl） diazenyl） phenol]. Using p-nitroaniline and phenol as raw materials,4-（（ 4-nitrophenyl） diazenyl） phenol was synthesized by diazotization and coupling reaction with the yield of 87%. The structure of 4-（（ 4-nitrophenyl） diazenyl） phenol was obtained by comparing the measured infrared spectrum absorption frequency with Gaussian calculation frequency,and it was evidenced by mass spectrum,the frequency value of main functional groups are extremely close,and therefore the synthetic product should be determined as the target product. Using XRD,SEM,the results show that the morphology and structure of magnesium hydroxide precipitate is changed effectively and the large granular and solitary precipitate is obtained by using the compound precipitant. The separation of lithium and magnesium in MgLi ratio of 60 simulation brine（ containing ρ（ Mg（2＋）） = 120 g /L; ρ（Li＋） = 2 g /L） is conducted by using the compound precipitant,the experimental results show that the magnesium ion is precipitated with rate of 99. 999%,the lithium-ion adsorption loss rate is less than 2%,and the filtration rate is greatly improved.