Study On A New Process Of Extracting Lithium From Salt Lake Based On Conventional Ion Exchange Membrane

The electrification of the world has promoted the strong growth of lithium demand,so it is particularly important to explore the new supply of lithium resources.At present,lithium extraction from salt lakes is recognized as the most important source of lithium resources.However,the ratio of magnesium to lithium in lithium-containing salt lake brine in China is generally high,and the separation is much more difficult than that in Chile and other countries.Therefore,the primary problem of extracting lithium from salt lake brine with high ratio of magnesium to lithium is the selective separation of magnesium and lithium ions.In recent years,this problem has attracted a large number of scientists,including the use of membrane separation methods.In this thesis,diffusion dialysis?DD?was applied to the separation of lithium and magnesium in salt lake brine for the first time by using conventional cation exchange membrane.The separation properties of simple systems?lithium chloride and magnesium chloride?and complex systems?close to the real brine of Eest taijinar salt lake?at different flow intensities and temperatures were studied systematically.The results showed that the selectivity of cationic exchange membrane was up to 6 in both systems.This performance is obviously higher than that of DuPont film with the same transmittance.In addition,the transport of Na⁺,K⁺,Ca²⁺,[B?OH?₄]^-,Cl^-,SO₄^2-in the complex system was investigated in detail.Furthermore,the mechanism of competitive transmembrane was also investigated.Therefore,this work innovatively applies diffusion dialysis technology to thermodynamic spontaneous selective separation of lithium and magnesium ions.It is expected that based on the existing conventional ion exchange membrane materials,a new idea for lithium extraction from salt lake is proposed,which provides a new possibility for the separation of lithium and magnesium in brine.