Study On Quantitative Analysis Of Lanthanum Beneficiation And Metallurgy Based On In-situ Gamma Spectroscopy

Extraction is an important part of rare earth element hydrometallurgy.The content of rare earth elements varies widely in the process.Feedback control of rare earth distribution test results greatly affects the quality of rare earth products.In this paper,in view of the technical requirements of rapid in-situ detection of rare earth element lanthanum extraction process,a method for detection of lanthanum content in the extraction process based on in-situ gamma spectroscopy was designed.By quantitatively analyzing the 1.435 Me V（65.5%）gamma ray emitted by 138La,an important associated natural radioisotope of lanthanum,during the decay process,the high-sensitivity and in-situ measurement of lanthanum content during extraction was achieved.The specific research contents and conclusions are as follows:（1）Optimize the measurement method of lanthanum extraction.An immersion in-situ lanthanum content detection unit is designed in the extraction pipeline.Build a mathematical model of the detection method.The calculation formulas of parameters such as limit of detection（L_D）,minimum detectable concentration of lanthanum MDC and detection sensitivity（S）were deduced.The key influencing factors such as the physicochemical properties（composition,phase state,density）,detector type,and specification of the extract were analyzed by the controlled variable method.The results show that L_D,MDC and S are greatly affected by the detector type and specification,but are less affected by the physicochemical properties of the extract.（2）On the basis of theoretical research,an experimental platform for the immersion in-situ lanthanum content detection method was built.Using different concentrations of La Cl₃anhydrous ethanol solution and aqueous solution to simulate the organic phase and water phase in the extraction process,the boundary value of detection efficiency was obtained;FALCON 5000 high-purity germanium gamma spectrometer was used to measure 138La in the pipeline,and the instrument L_D MDC and S parameters was obtained.The results show that the instrumental L_D of the organic phase is 7.94×10^-3 cps,the S is 1.90×10^-3cps/（g/L）,and the MDC is 4.66 g/L;the instrumental L_D of the aqueous phase is 8.52×10^-3cps,S is 1.85×10^-3 cps/（g/L）,MDC is 4.99 g/L,which is lower than the concentration of lanthanum in the extraction process.（3）In order to further improve the detection sensitivity S,the trapezoidal background method and the SNIP method were used to study the background subtraction of the gamma measurement spectra of extracts with different concentrations.Combined with the least squares method,the"net count rate"and"lanthanum content"were fitted to obtain the working curve under the experimental conditions.The results show that for the measurement spectra of medium and high concentrations,the errors of the trapezoidal area method and the SNIP method are both lower than 10%;for the measurement spectrum of low concentration,the error of the SNIP method is 58%,and the error of the trapezoidal background method is lower than 15%.The working curve obtained by the trapezoidal background method has higher accuracy and sensitivity,and has better applicability to low-content solutions.