| Lithium ,boron have unique physical and chemical properties, the field of application is very extensive. In the metallurgical industry, lithium is used as reductant or gas eliminate agent. In batteries, lithium battery using lithium metal as negative electrode, is commonly used in notebook computers, mobile phones, cameras and began a trial of electric vehicles.In the energy sector, propellant made from lithium or lithium compounds can be used as the driving force of the rockets, missiles, spacecraft. Boron used in glass industry, can reduce the melting time and improve transparency. The superconducting materials made of boron, has a broad application prospects in the electronics and computer fields. In nuclear industry, boron can be used as control rods in the reaction. The Salt Lake Brine in China is rich in lithium and boron resources. At present, the development of lithium and boron resources brings in the environment pollution. Therefore, we carried out extraction of lithium and boron from salt lake brine, which the ionic liquids were used as green extraction medium. It has important practical significance.Synthesized five kinds of 1 - alkyl - 3 - methylimidazolium hexafluorophosphate ([CnMIm][PF6]) ionic liquids, where n is 4,6,8,10,12, and the ionic liquid physical and chemical properties were determined.We design a model for study on extraction of lithium from salt lake brine,in which ionic liquids were used as extraction medium, FeCl3 was used as synergic reagent, tributyl phosphate (TBP) was used as extracting agent, that was employed for investigating effects of ionic liquid and extraction conditions on the lithium extraction. The optimal extraction conditions of the system include TBP/IL of 9/1(v/v), 0.03 mol·L-1 HCl, O/A of 1:1 and Fe/Li of 2:1. Under optimal conditions, single extraction rate was 87% . we also study the repeat utilization of the organic phase,when the organic phase was reused for ten times,the extraction rate was 77%. The back-extraction efficiencies of lithium was 90% with 6 mol·L-1HCl,and the O/A of 15:1.In the experiments of the extraction of boron, we determination of boric acid by azomethine-H spectrophotometric, and we optimize the conditions of color reaction. We design a model for study on extraction of boron from salt lake brine,in which ionic liquids were used as extraction medium, the isooctyl alcohol were used as complexing agents, the kerosene were used as diluent,that was employed for investigating effects of ionic liquid and extraction conditions on the boron extraction.The optimal extraction conditions includ extraction time: 10 min, the concentration of extracting agent: 50%(cv), the dosage of ionic liquids: 10% (v/v), the O/A: 1:1, the concentration of Mg2+: 4.27 mol·L-1, pH: 2.4.With three step of extraction, the extraction rate is 99%. With water as back- extractant, the A/O of 0.7:1, and three strep back-extraction, the back-extraction efficiencies of boron was 85.7%. The boron recovery was 70%. The combination of three step extractions with two step water washed can simulate industrial continuous operation, it's result was similar to the industrial's.With 1 mol·L-1 HCl, and the (O/A) 15:1, washed the organic phase by combination of three step extractions with two step water washed, the Mg/Li mass ratio has been reduced to 2.21.The concentration of lithium changed little after extraction of boron ,but concentration of boron decreased by 42% after extraction of lithium,so we determine extraction of boron first, and then extraction lithium.Respectively, under the optimal extraction conditions of the lithium and boron,with three extraction of boron, extraction of lithium from the remaining water phase by three step extractions, the lithium extraction rate was 99%, it can achieve the joint extraction of boron and lithium. |
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