Determination of lithium oxide in lithium ore by inductively coupled plasma atomic emission spectrometry with super microwave digestion
The content of lithium oxide in lithium ore is the key factor affecting the price of lithium ore.The atmospheric decomposition method is commonly adopted for the determination of lithium oxide in lithium ore,but it has some problems such as complicated operation and large consumption of acid.The sample was treated with 1.5 mL of sulfuric acid and 2.0 mL of hydrofluoric acid by super microwave digestion at 280 ℃.After digestion,the solution was continuously heated until sulfuric acid fuming to remove silicon and excessive hydrofluoric acid.The salts were redissolved with 1.0 mL of sulfuric acid and 25 mL of wa-ter by heating,and lithium in the test solution was determined by inductively coupled plasma atomic emis-sion spectrometry(ICP-AES)with Li 610.365 nm as analytical line and emission power as 0.95 kW.Con-sequently,a method for determination of lithium oxide in lithium ore was established by ICP-AES after su-per microwave digestion.The mass concentration of lithium in range of 0.50-50.0 mg/L showed good line-ar relationship with its corresponding emission intensity.The correlation coefficient(r)was 0.999 7.The limit of detection of this method was 1.5 mg/kg for lithium oxide.The contents of lithium oxide in three lithium ore samples were determined according to the proposed method,and the relative standard devia-tions(RSD,n=8)of determination results were between 0.92％and 2.0％.The proposed method was applied for determination of two certified refence materials of lithium ore,and the results were consistent with the certified values.Two assay laboratories were selected for determination of the contents of lithium oxide in lithium ore samples according to the proposed method,and the results were consistent.Compared with the current standard methods of GB/T 509.1-2008 and GB/T 17413.1-2010,this method could save 80％of hydrofluoric acid dosage during digestion,and it is suitable for rapid inspection and clearance of im-ported and exported lithium ore
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