Study On Rapid Detection Of Lithium Carbonate Based On Salt Lake By Fluorescence Probe Method

High purity lithium carbonate is the breakthrough point of the salt lake chemical industry to new energy industry,but it has been restricted by technical bottlenecks such as high lithium loss rate and interference from magnesium salts in the preparation process for many years.In the dynamic process of separating primary lithium carbonate from salt lake brine and refining it,it is often difficult to remove all magnesium impurity salts,and the loss rate of lithium can reach about 15%～40%.However,it is difficult to detect the dynamic the dynamic direction or migration path of these magnesium lithium components in real-time,so the process optimization has to rely on empirical exploration.If the migration tendency of magnesium and lithium components can be learned immediately,it will be helpful to improve the actual benefit of lithium extraction and refining processes in brine.Considering the market price of lithium carbonate of 200,000 to 620,000 yuan/ton in recent years,it is necessary to develop a new method for real-time detection of lithium magnesium liquid phase for process strengthening.Based on the existing production technology of lithium carbonate,this article proposes the idea of rapid detection of magnesium and lithium by laser induced fluorescence probes.Through the synthesis of specific fluorescence probe,the real-time in-situ detection of Li⁺concentration changes in the production of industrial lithium carbonate is facilitated,and the impurity Mg²⁺contained in the refining process of high purity lithium carbonate is realized.Specific research contents and conclusions are as follows:Li⁺fluorescent probe（No.L）was synthesized to realize rapid recognition and response of Li⁺in salt solution.Li⁺Probe L was synthesized from 12-crown 4-ether and 1,8-naphthalic anhydride.Probe L has good selectivity for Li⁺and can be complexed with Li⁺at 1:1 coordination ratio.The binding constant between probe L and Li Cl O4 is 107 M^-1 by nonlinear fitting calculation,indicating that probe L has good binding ability with Li⁺.The rapid Li⁺recognition process of probe L can be carried out in salt solution,without any other complex pretreatment of the Li⁺samples,showing a fluorescence enhancement effect and good stability.Mg²⁺fluorescent probe（No.A）was synthesized to stimulate immediate response to Mg²⁺in salt solution environment.Mg²⁺fluorescent probe A was synthesized from 2-（2hydroxy-phenyl）benzoxazole by tri（hydroxy-methyl）amino methane.Mg²⁺in salt solution could be selectively recognized directly,and Mg²⁺was formed into a complex with 1:1coordination ratio with Mg²⁺.The fluorescence emission spectra showed obvious fluorescence enhancement effect,and the recognition process was stable and had good anti-interference ability.Based on the synthesis of Li⁺and Mg²⁺fluorescent probes,it was applied to the rapid detection of the concentration change of Li⁺in the production of industrial lithium carbonate and the content of Mg²⁺in the refining process of lithium carbonate.Timely detected in rich lithium experiments Li⁺concentration rising signs of slowing,adjust process,reduced the loss rate of Li⁺28%,the fluorescence intensity in the process of detection and has good linear relation between Li⁺concentration,R²=0.9614,the detection limit of 1.9462μmol/L.In the experiment of refining lithium carbonate by carbonization method,the change of Mg²⁺removal rate is captured in time,and the process is adjusted to effectively shorten the removal time of Mg²⁺,and the detection of Mg²⁺can be completed within 5～10 S.There is a good linear relationship between the fluorescence intensity generated in the detection process and the concentration of Mg²⁺,R²=0.9876,the detection limit of 2.9845μmol/L.In conclusion,this study can overcome the technical bottleneck,realize in situ rapid detection of magnesium lithium components in the production process of lithium carbonate and refining process,contribute to the improvement of benefits in the production and refining process of lithium carbonate,provide theoretical guidance for the efficient operation of lithium carbonate process,and ensure the sustainable utilization of salt lake resources.