The Method Of The Separation,purification And The Theoretical Study Of Lithium Form Salt-lake Brine

Since the explosive growth of new energy vehicles in 2015,the world's lithium demand has increased rapidly,and accelerating the development of lithium resources is of great significance.The lithium resources in my country are quite abundant,and the salt lake brine contains huge energy.Among them,the extraction method of lithium extraction has gradually become a hot method for lithium extraction with brine due to its low cost,environmental protection,and simple process flow.At present,most of the extraction methods still use Fe Cl₃as a co-extractant,add an extractant diluent as an extraction system,and focus on the research of the type of extractant and diluent.This topic provides new ideas for the separation and extraction of lithium using new extractants.In this experiment,the deboronated brine was used as the raw material,and the organic reagents N414?N218 and O4228 with amide groups independently synthesized in the laboratory were used to separate and extract the lithium in the salt lake brine by solvent extraction.The contents are as follows:(1)In this experiment,the extraction agent,co-extraction agent,and diluent were screened repeatedly for many times.Based on the extraction rate,reaction equilibrium time,organic phase aqueous phase stratification state,and whether the raw materials were cheap and easily available,ICP(High-frequency inductively coupled plasma atomic absorption spectrometer)measured ion changes before and after extraction,and the final extraction system selected was:N414-N218-O4228-white oil system.After the extraction system was determined,a single extraction experiment was carried out on the demagnetized brine with high magnesium to lithium ratio,and the single extraction rate was stable at about 78%.After that,the extraction conditions are optimized to achieve the optimal level.The result of the single-factor experiment is that the optimal experimental ratio is:50%N414-25%N218-10%O4228-15%white oil,compared with(O/A)=2:1,Fe/Li=1.15:1,p H value of the aqueous phase=1.5,at this time,the single extraction rate of lithium reaches 84%.(2)In addition to the deboronized brine,the extraction system also extracts low magnesium and lithium ratio brines such as Chenzhou brine and lithium sink mother liquor.The results show that the N414-N218 extraction system is more suitable for high magnesium lithium brine brines and other metal ions.Has good selectivity.(3)Through theoretical calculation of the reaction thermodynamic coefficients at different temperatures,it is known that this extraction reaction is an exothermic reaction.A comparative study of the shift of the characteristic peaks of the infrared spectrum before and after the extraction of the N414-N218 system and the color change of the organic phase of the water phase verify that the structure of the loaded phase undergoes ion exchange.The innovation of this experiment is that the N414-N218 extraction system not only achieves a high lithium extraction rate,but also keeps the extractant stable during the extraction process,even if the p H of the aqueous phase is slightly higher,the organic phase does not emulsify the aqueous phase after extraction The value is almost unchanged,which effectively solves the problem that the organic phase in the current solvent extraction method is easy to emulsify and degrade.Compared with the ionic liquid extractant with the same stabilizing effect,the raw material of the extractant used in this experiment is cheap and readily available,and is more suitable for industrial production.