Determination of lithium in lithium ore by inductively coupled plasma atomic emission spectrometry with high-pressure closed digestion
Lithium ore is an important national strategic resource.The accurate determination of lithium content in lithium ore is of great directive significance for the mining and processing of lithium ores.The sample cannot be fully digested in acid mixture system in open environment or there is loss for lithium in digestion process,which cannot meet the requirements of accurate determination.In this study,the sam-ple could be digested completely with nitric acid-hydrofluoric acid system in a high-pressure closed system at 190 ℃.Thus,a method for determination of lithium in lithium ore by inductively coupled plasma atomic emission spectrometry(ICP-AES)was established with Li 670.784 nm as analytical line.The standard so-lution series were prepared by matrix matching method to eliminate the influence of matrix effect on the de-termination.The coexisting elements such as calcium,sodium,potassium,magnesium,iron,manganese and phosphorus had no influence on the determination.The mass concentration of lithium in range of 0.50-50 μg/mL showed good linear relationship with its corresponding emission intensity,and the linear correla-tion coefficient of calibration curve was 0.999 8.The limit of detection of method was 0.003％.The pro-posed method was applied for determination of certified reference materials and samples of lithium ore.For certified reference materials,the results were basically consistent with the certified values,and the relative standard deviations(RSD.n=12)of determination results were between 0.84％and 1.4％,then the rela-tive errors(RE,n=12)were between-1.24％and 0.51％.For lithium ore samples,the RSDs(n=12)of determination results were between 1.6％and 2.0％,and the recoveries were between 98％and 104％.
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